Print
Genera of the Protura of the World: diagnosis, distribution, and key
expand article infoLoris Galli, Julia Shrubovych§|, Yun Bu#, Matteo Zinni
‡ Università di Genova, Genova, Italy
§ Institute of Systematics and Evolution of Animals, Polish Academy of Sciences, Krakow, Poland
| State Museum of Natural History, Ukrainian Academy of Sciences, Lviv, Ukraine
¶ Institute of Soil Biology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
# Shanghai Science & Technology Museum, Shanghai, China
Open Access

Abstract

Protura are known all over the world with more than 800 described species belonging to three different orders (Acerentomata, Sinentomata, and Eosentomata) and seven families (Hesperentomidae, Protentomidae, Acerentomidae, Fujientomidae, Sinentomidae, Eosentomidae, and Antelientomidae). At present 76 genera are known worldwide. In this paper a description of the diagnostic characters of these genera and an updated key for their identification are reported.

Keywords

distribution, key to genera, Protura, World

Introduction

Since their discovery (Silvestri 1907), the knowledge of Protura has rapidly increased all over the world thanks to the careful research of many specialists. For example, the number of worldwide genera cited by Tuxen (1964), Nosek (1978a), Yin (1983) and Szeptycki (2007) was 22, 40, 54 and 72, respectively. Four new genera (Nanshanentulus Bu & Yin, 2007, Osientomon Nakamura, 2010, Liaoxientulus Wu & Yin, 2011, Nosekientomon Shrubovych et al., 2014b) have been described after the publication of Szeptycki’s Catalogue (2007), but since Yin (1983) there has not been published an updated key for the worldwide genera of Protura. In the belief that such a key is an essential tool for those researchers who want to study in detail this still poorly known taxon, this paper describes the diagnostic characters of the 76 genera known to date worldwide, accompanied by a key for their identification.

The diagnostic characters used at a generic level for Protura have changed and increased in number thanks to the contributions from different authors during the last century. In the first papers published on Protura (Berlese 1908a, 1908b, 1909; Silvestri 1909) just four genera (Acerentomon, Acerentulus, Proturentomon, and Eosentomon – the possibility of subgenus Acerella was suggested in Berlese, 1909) were described mainly based on the presence/absence of a tracheal system, presence/absence of a rostrum, shape and size of mouthparts (maxillae, mandibles, maxillary, and labial palps), the number of segments of abdominal appendages and presence/absence of teeth on the lid (comb) covering the large glands on the sides of tergite VIII. In 1921 Ewing redescribed the genera Eosentomon, Acerentomon, and Acerentulus and described three new genera Protentomon, Acerentuloides, and Microentomon (the last one subsequently rejected). In his paper he stressed the importance of the size of abdominal appendages (one or two-segmented) and introduced for the diagnosis of genera the importance of tergal plates, the shape and size of tergal apodemes on the meso- and metanotum and on the first eight urotergites and the presence of transverse rows of dorsal setae on abdominal segments. The same characters, with reference also to the comb of urotergite VIII, were used by this author in his 1936 Synopsis of the genera of Protura. In a more extensive paper Ewing (1940) described genera of North American Protura based on dorsal apodemes, labrum, maxillae, mandibles, the number of transverse rows of setae on abdominal segments, presence of pectinated structures, characteristics and relative size of legs, colour and degree of sclerotization of cuticle (the size of abdominal appendages was elevated as a diagnostic character at a family level). Meanwhile, labial and tarsus ratios (LR and TR), chaetotaxy and details of both foretarsal sensilla/setae and female squama genitalis shape were introduced by Womersley, Ionescu and Condé, respectively, but such characters were used almost exclusively for new species description. In 1959, in their Synopsis of the Japanese Protura, Imadaté and Yosii described the new genus Nipponentomon based on previously used characters but included the number of setae shared by the four species of the genus on some of the abdominal segments and the distribution and shape of the abdominal pectinated structures. In 1964 Tuxen published his valuable monograph on the World Protura. Each genus was identified using characters such as abdominal appendages (size, number of setae and their relative size), shape and relative position of key sensilla on the foretarsus, presence and size of a rostrum, development of maxillary and labial palps, and shape of the maxillary glands. However, in addition to the important diagnostic features Tuxen provided meticulous descriptions of every part of the body morphology: e.g., the number of setae and sensilla on the labial and maxillary palps, the structure of all foretarsal sensilla present (and noting those absent), and the abdominal chaetotaxy. A similar scheme was followed by Nosek (1973) and Imadaté (1974) in their monographs on European and Japanese Protura, respectively, but the last author added the chaetotaxy of nota and, for Acerentomidae, the position of seta P3 on abdominal tergites II–VI (diagnostic character he had suggested in 1964) in his diagnoses of genera. At the same time, Rusek (1974) examined in detail the taxonomy of Acerentomidae, redescribing older genera and introducing five new genera (Vesiculentomon, Imadateiella, Filientomon, Verrucoentomon, and Nosekiella), based on the following diagnostic characters: number and relative length of setae on abdominal appendages, shape of the maxillary glands, shape of sensillum t1 and relative position of some sensilla on the foretarsus (mainly a’ respect to t2, d respect to e and c, f respect to g), number of anterior setae on the metanotum and toothed rows on the hind border of the last abdominal segments. Nosek (1978a) published a paper on the genera of Protura of the world. In the diagnosis of each genus he described the labial and maxillary palps, mandibles, maxillary glands, pseudoculi, some main foretarsal sensilla (e.g. t1 and t3), abdominal appendages, chaetotaxy of sternite VIII, striate band (in Acerentomidae), comb VIII, and female squama genitalis; other characters (like the number of anterior setae on metanotum) are provided just in a few cases. Three years later Tuxen (1981) undertook a taxonomical revision of Acerentomidae based on the degree of development of the striate band of abdominal segment VIII, stressing the importance of the hook-shaped design, the number and relative size of setae of abdominal appendages (legs) and other characters (chaetotaxy of metanotum, shape of foretarsal sensillum t1, labial palps and maxillary glands). Based on these features he introduced the new genera Kenyentulus (splitting Gracilentulus) and Amphientulus (from Berberentulus). The next year Tuxen and Yin (1982) revised Protentomidae and introduced the new genus Neocondeellum (from Condeellum) based on shape of pseudoculi, maxillary palps, foretarsal sensilla, abdominal appendages, presence of a serrated line on abdominal segment VIII, comb VIII and chaetotaxy. Characters such as the presence/absence of a tracheal system, thoracic and abdominal chaetotaxy, pseudoculi, maxillary glands, labial palps and shape of foretarsal sensilla were used by Yin (1983) to arrange her phylogeny of Protura, grouping the 54 then known genera into 17 subfamilies and eight families. Zhang and Yin (1984) revised the subfamily Anisentominae and created the new genera Neanisentomon, Pseudanisentomon and Paranisentomon based mainly on the presence/absence and shape of few foretarsal sensilla (t2, f1, b’2) and on the chaetotaxy of abdominal segment VIII. Szeptycki (1988) introduced the term porotaxy to define the distribution of pores on the body of proturans and suggested the possibility of using this character for the identification of genera. Since then porotaxy has been generally used in the description of new species. Szeptycki (1995a) summarized the knowledge about porotaxy of Protura and reiterated the taxonomic importance it could have at the level of genus and family. Szeptycki also (see 1997) introduced the analysis of the shape of accessory setae (especially of meso- and metanotum) as a taxonomically important character (at least for Acerentomata). Unfortunately, porotaxy and the shape of accessory setae of the majority of species are still unknown and, for many genera, their use as diagnostic characters is not practicable. Nevertheless, they are among those characters used by Shrubovych (2014) in her cladistic approach to the Acerentomidae of Northeastern Palearctic. Other useful diagnostic characters are the head chaetotaxy and porotaxy (Rusek et al. 2012); currently they are mainly provided in new species description, but some, like the presence/absence of postpseudocular seta, have been used for the diagnosis of new genera (e.g. Wu and Yin 2011).

Diagnosis

Nosek’s (1978a) diagnostic framework is partly used and integrated with the new genera described and updated in accordance with the more recent taxonomic revisions and redescriptions of Nakamura (2010), Shrubovych and Rusek (2010), Shrubovych et al. (2012a), Shrubovych and Smykla (2012), Shrubovych et al. (2014b).

For the whole bibliographic references to genera description and distribution, we refer to the World Catalogue by Szeptycki (2007). Genera are listed according to Szeptycki’s system (2007).

The diagnostic characters available for each genus are given, following the same general scheme: characters related to the head (especially the labial palps, maxillary glands and pseudoculi), foretarsal sensilla and setae (presence/absence, position, size and shape), notal chaetotaxy, abdominal appendages (number of segments and setae), other abdominal characters (chaetotaxy, striate band, comb VIII) and shape of female squama genitalis. When available and useful for taxonomic diagnosis, other characters considered are the presence of a rostrum and the cephalic chaetotaxy. Those unifying characters reported in the order, family or subfamily diagnosis are not repeated in that of genera. For the characters described in the diagnosis and used in the key, refer to Tuxen (1964), Nosek (1973), Tuxen and Imadaté (1974), Tuxen (1981), Tuxen and Yin (1982), Yin (1999), Rusek et al. (2012) and Shrubovych (2014). For the appearance/shape of some characters (e.g. the foretarsal sensilla and the maxillary glands) would be appropriate to consult directely the type species description or those papers indicated in the remarks of the genera.

Abbreviations

abd. abdominal segment/s,

abd. app. abdominal appendages,

Tg. abdominal tergite/s,

St. abdominal sternite/s,

A-setae anterior setae,

P-setae posterior setae,

Pc posterior central seta.

Order ACERENTOMATA Yin, 1996

Tracheal system missing. Dilated canal of maxillary glands. Foretarsus typically with three dorsal sensilla (t1t3), seven external (ag) and three internal (a’–c’). Abd. app. with no more than four setae. Presence of pectinated structures on the abdomen. Glands on abd. VIII covered by combs. Abd. VIII with striate band (fully developed or reduced). Female squama genitalis without processus sternalis but with acrostylus.

Family Hesperentomidae Price, 1960

Labial palps well developed, with tuft of setae. Maxillary glands long and dilated. Abd. app. I two-segmented, with terminal vesicle and four setae; II–III two-segmented or uni-segmented. Striate band without distinct striae. Comb VIII rectangular with small teeth. Female squama genitalis with pointed acrostyli.

Subfamily Hesperentominae Price, 1960

Maxillary palps with tuft of setae and two sensilla. Labial palps with tuft of setae and three distinct setae. Canal of maxillary glands with a long dilation. Pseudoculi open proximally. All foretarsal sensilla present, with addition of c”. Metanotum with median setae and two pairs of A-setae. Abd. app. I and II two-segmented, each with terminal vesicle and four setae; III two-segmented or uni-segmented with two setae.

1 – Hesperentomon Price, 1960

Labial palps without basal sensillum. Canal of maxillary glands dilated as a long parallel-sided sac for most of its length, narrowing proximally. Pseudoculi pear-like, strongly elevated and with a median S-shaped cleft. Foretarsal sensilla setiform or longish willow leaf-shaped. S seta long, straight and pointed. Abd. app. I–III two-segmented, each with four setae. St. II–VI with Pc seta (absent only on St. IV–VI in few species). St. VIII with a single posterior row of six setae. Abd. VIII with a serrated line at the anterior border. Fine teeth at the hind border of St. IX–X.

Type species. Hesperentomon macswaini Price 1960.

Distribution. East and Central Asia, North America.

Remarks. For figures and a key to species of genus Hesperentomon, see Shrubovych (2010).

2 – Ionescuellum Tuxen, 1960

Labial palps with basal sensillum. Canal of maxillary glands with calyx, a long dilation and a second round dilation distal to calyx. Pseudoculi oval and open proximally. Abd. app. I-II two-segmented, each with terminal vesicle and four setae; appendage III uni-segmented with two setae. St. II–VI without Pc seta. St. VIII with 4/0 setae.

Type species. Paraentomon carpaticum Ionesco, 1930.

Distribution. Europe.

Remarks. Figures and a key to species of genus Ionescuellum are available in Rusek and Stumpp (1989).

Subfamily Huhentominae Yin, 1983

Labial palps well developed with tuft of setae and three distinct setae, without basal sensillum. Metanotum with one or two pairs of A-setae. Abd. app. I two-segmented; II–III uni-segmented, each with three setae, the median apical one approx. twice the length of the others. St. IV–VII each with Pc seta; St. VIII with 2/4 setae.

3 – Huhentomon Yin, 1977

Canal of maxillary glands extremely long; middle part approx. 3.5 times of hind part, with a tiny racemose appendix distally. Pseudoculi with a median S-shaped opening. Foretarsal sensilla of Hesperentomon type; sensillum t1 filiform; t3 rather long, sensilliform; b’, c’ and c” distal, close to t3; d nearly halfway between c and e, distal to t2.

Type species. Huhentomon plicatunguis Yin, 1977.

Distribution. China, Japan.

Remarks. Figures and comparison between the two species of genus Huhentomon are available in Imadaté (1989).

Family Protentomidae Ewing, 1936

Small bodied Protura. Maxillary glands with smooth globular calyx. Foretarsal sensillum t1 sometimes missing (in all the species belonging to genus Protentomon and some of those belonging to Proturentomon). Metanotum with one or two pairs of A-setae. Abd. app. I–II two-segmented, each with terminal vesicle and three or four setae; III two-segmented or uni-segmented with two or three setae.

Subfamily Hinomotentominae Yin, 1999

Abd. app. two-segmented, each with terminal vesicle and four setae. Female squama genitalis with pointed acrostyli.

4 – Hinomotentomon Imadaté, 1973

Maxillary palps with tuft of setae and two sensilla. Labial palps with tuft of setae, three distinct setae and basal sensillum. Canal of maxillary glands with heart-shaped calyx with verrucose appendices and a proximal dilation. Pseudoculi with a large triangular prolongation in the proximal part. Foretarsal sensillum a’ short; b’ and c’ missing. Metanotum with two pairs of A-setae. St. IV–V without Pc seta. St. VIII with four setae. Comb VIII with 10 small teeth.

Type species. Hesperentomon nipponicum Imadaté, 1964.

Distribution. Japan.

Remarks. For figures, see Imadaté (1973).

Subfamily Condeellinae Tuxen & Yin, 1982

Labial palps with tuft of setae. Metanotum with median setae and two pairs of A-setae. Abd. app. I–II two-segmented, each with four setae; III uni-segmented with two or three setae. Female squama genitalis with pointed acrostyli.

5 – Condeellum Tuxen, 1963

Labial palps without basal sensillum. Sensillum of maxillary palps slender and pointed. Canal of maxillary glands with heart-shaped dilation, the proximal part only dilated along half its length; no proximal globule. Pseudoculi fairly large (PR = 8–10), circular, elevated over the head surface, without lever. Four dorsal setae between pseudoculi (d4 and sd4) and two setae lateral to these (l3). Foretarsi with only four setiform sensilla in the exterior and interior side, respectively: a, b, f and a’; sensilla t1 and t2 are long, thin and pointed. Seta S long. Abd. app. III uni-segmented with three setae, the median apical one approx. twice the length of the others. St. I–VII with four A-setae; IV–VI with Pc seta. St. VIII with six setae in a row. Comb VIII mostly without teeth.

Type species. Proturentomon regale Condé, 1958.

Distribution. Subtropical China, Pacific Islands, Tropical Asia, Reunion.

Remarks. Figures and comparison between species of genus Condeellum are available in Tuxen and Yin (1982) and Imadaté (1991).

6 – Neocondeellum Tuxen & Yin, 1982

Two short and blunt sensilla on maxillary palps. Labial palps without basal sensillum. Canal of maxillary glands, with a globular bladder, in connection with the canal, but not with a simple calyx. Pseudoculi small (PR = 14–18), with a short lever. Four dorsal setae between the pseudoculi (d4 and sd4); lateral setae l3 missing. Foretarsi with only four sensilla in the exterior and interior side, respectively: a, b, f and a’. Abd. app. III uni-segmented with three setae, the median apical one longer than the lateral. Anterior row of Tg. II–VII with at most six setae. Tg. VIII with a single serrate line (striate band) rarely with indication of an anterior border. St. IV–V without Pc seta. St. VIII with six setae. Comb VIII with approx. ten very small teeth.

Type species. Condeellum brachytarsum Yin, 1977.

Distribution. China, Japan, North America.

Remarks. For figures and comparison between species of genus Neocondeellum, see Tuxen and Yin (1982). For a more recent key to eight Neocondeellum spp., see Nakamura (1990).

7 – Paracondeellum Yin, Xie & Zhang, 1994

Calyx of maxillary glands globular and smooth. Pseudoculi circular without lever. Foretarsal sensilla of the exterior side fully developed; b’ and c’ missing. Abd. app. III uni-segmented with two setae, the median apical longer than the lateral one. Tg. I with one pair of anterior setae; Tg. II–VII without A-setae. St. II–III with three P-setae; St. IV–V with nine P-setae; St. VIII with 4/0 setae.

Type species. Condeellum dukouensis Tang & Yin, 1988.

Distribution. China.

Remarks. For figures, see in Yin et al. (1994).

Subfamily Protentominae Ewing, 1936

Labial palps with tuft of setae. Pseudoculi with a long proximal prolongation. Foretarsi with foliaceous or bacilliform (long, parallel-sided, with blunt apex) sensilla. Metanotum with median setae and one or two pairs of A-setae. Abd. app. I–II two-segmented and III uni-segmented, with 4-4-2 or 3-3-2 setae. St. VIII with 4/0 setae. Female squama genitalis with knob-like acrostyli and two median papillae between styli.

8 – Protentomon Ewing, 1921

Labial palps with or without basal sensillum. Canal of maxillary glands with disc-shaped dilation and sac-like proximal dilation. Pseudoculi mostly elliptical, with a narrow and long (more than pseudoculi) proximal prolongation. Foretarsi relatively short; t1 absent; c sometimes missing. Metanotum with two pairs of A-setae (A2, A4). Comb VIII mostly without teeth, sometimes with very fine teeth, similarly to the hind margin of Tg. XII.

Type species. Protentomon transitans Ewing, 1921.

Distribution. Cosmopolitan.

Remarks. For figures, see Nosek (1973, 1976), Bernard (1975), Tuxen (1977a).

9 – Proturentomon Silvestri, 1909

Labial palps with or without basal sensillum. Canal of maxillary glands with disc-shaped dilation and sac-like proximal dilation, with sharp proximo-lateral corner, terminating in doubled globule. Pseudoculi with a large triangular proximal prolongation of the same length of pseudoculi and of almost the same width distally. Foretarsi sometimes missing sensillum t1; c always present; sensilla on exterior and interior side of foretarsi are foliaceous or bacilliform, respectively. Seta S blunt, relatively short. Metanotum with one pair of A-setae (A2). Comb VIII with distinct teeth. The hind border of Tg. IX–XI serrated.

Type species. Acerentomon minimum Berlese, 1908.

Distribution. Holarctic.

Remarks. For figures, see Rusek (1975 – with a key to nine Proturentomon spp.), Szeptycki (1988) and Yin (1999).

Family Acerentomidae Silvestri, 1907

Mesonotum with a pair of median setae and two or three pairs of A-setae; metanotum with a pair of median setae and two to four pairs of A-setae. Abd. app. I two-segmented with four setae; II and III each uni-segmented with one to three setae. Abd. VIII with striate band.

Subfamily Berberentulinae Yin, 1983

Labial palps generally reduced (without tuft of setae) with two to four setae and one sensillum. Maxillary glands with generally smooth and often heart-shaped calyx. Foretarsal sensillum t2 usually setiform/filiform. Meso- and metanotum each with two pairs of A-setae (A2, A4). Striate band on abd. VIII often reduced.

10 – Acerentuloides Ewing, 1921

Maxillary palps with two spindle-like sensilla. Labial palps with a terminal tuft of setae and a sausage-shaped basal sensillum. Canal of maxillary glands with proximal part as long as the proximal part of fulcrum, ending with a row of small globules which increase in size proximally and end with two globules placed beside each other. Pseudoculi small. All foretarsal sensilla present, of average length; sensillum t1 claviform; t3 long lancet-like or finger-like; d closer to c than to e; a’ close to the base of t1. Abd. app. II–III each with three setae, the median apical one reduced to little more than its pit. Tg. II–VI with seta P3 in anterior position. St. I–VII with three setae in anterior row. St. VIII with 4/2 setae. Striate band well developed. Comb VIII with a row of approx. ten equal small teeth. Some setae modified as short, thickened sensilla (sd5 on head; β1 and δ4 on foretarsi; setae P4 on metanotum, M2 on prosternum and A2 on thoracic sterna; accessory setae on Tg. and St. I–VI). Female squama genitalis tripartite with pointed acrostyli as in Acerentulus.

Type species. Acerentuloides bicolor Ewing, 1921.

Distribution. North America.

Remarks. For figures and diagnosis, see Shrubovych et al. (2017).

11 – Acerentulus Berlese, 1908

Maxillary and labial palps with two and one sausage-shaped sensilla, respectively, and with a tuft of setae. Canal of maxillary glands with simple dilation, calyx sometimes weakly verrucose, proximal part rather long. Pseudoculi oval or circular with divided lid and short fork-shaped prolongation on the posterior margin of the lid. On foretarsi sensillum t1 claviform; t3 willow leaf-shaped; a’ usually broad; b’ always present. Abd. app. II–III each with three setae; the subapical is long, the lateral apical shorter and the median apical the shortest. Seta P3 on Tg. II–VI placed anteriorly to the row of the other P-setae. St. I–VII with three anterior setae. St. VIII with 4/2 setae. Striate band on abd. VIII well developed. Comb VIII with approx. ten teeth. Female squama genitalis distally tripartite.

Type species. Acerentomon confine Berlese, 1908.

Distribution. Cosmopolitan.

Remarks. Figures and recent keys to the species of the confinis and cunhai group are available in Shrubovych et al. (2012b) and Shrubovych et al. (2014d), respectively.

12 – Amazonentulus Yin, 1989

Labial palps reduced to three setae and a sensillum. Canal of maxillary glands of middle length, proximally bipartite. Foretarsal sensillum t1 claviform; t3 very long and awl-shaped; b’ absent. Abd. app. II–III each with two setae, the apical one shorter than half length the subapical. Tg. I–VII with uneven number of anterior setae. St. VIII with 4/0 setae. Striate band on abd. VIII reduced, without or with very short striae. Comb VIII with five to eight small teeth. Female squama genitalis with sharp pointed acrostyli.

Type species. Berberentulus brasilianus Nosek, 1973.

Distribution. South America.

Remarks. For figures, see Tuxen (1976).

13 – Amphientulus Tuxen, 1981

Labial palps reduced to three setae and a sensillum. Canal of maxillary glands simple. Foretarsal sensillum t1 claviform; t3 jar-shaped; b’ present; b most often shorter than c. Abd. app. II–III each with a long subapical seta and a strong lateral apical one. St. VIII with 4/0 or 4/2 setae. Striate band on abd. VIII reduced (often showing an hook-shaped design). Comb VIII oblique, with large teeth. Female squama genitalis with long acrostyli.

Type species. Berberentulus validus Tuxen, 1967.

Distribution. Australia, New Zealand, South America, China, Madagascar (doubtful).

Remarks. For figures, see Tuxen (1967, 1986), Imadaté (1973), Nosek (1978b).

14 – Andinentulus Tuxen, 1984

Labial palps reduced to three setae and a sausage-like sensillum. Proximal part of canal of maxillary glands almost as long as proximal branch of fulcrum. Foretarsi with all sensilla present; t1 claviform; t3 knob-shaped; a’ extremely long, situated between the insertions of t1 and t2; b’ present; d near the base of c. Abd. app. II–III each with three setae. Tg. II–VII with seta P3 in anterior position. Tg. II–V with six A-setae. St. I–VII with three A-setae. St. VIII with 4/2 setae. Striate band on abd. VIII reduced. Female squama genitalis with short basal arms, slender acrostyli with long and pointed apex.

Type species. Andinentulus rapoporti (Condé, 1963) (Andinentulus ebbei Tuxen, 1984 is synonymised after Shrubovych et al. 2014e).

Distribution. South America.

Remarks. For figures, see Shrubovych et al. (2014e).

15 – Australentulus Tuxen, 1967

Labial palps reduced to three setae and a sensillum. Canal of maxillary glands with heart-shaped calyx and a proximal tripartite dilation. Foretarsal sensillum t3 shaped as a bud rounded at apex, parallel-sided two to five times as long as broad; t1 claviform; a’ broad; b’ present. Abd. app. II–III each with three setae. Seta P3 on Tg. II–VI anterior to other P-setae row. St. VIII with 4/0 setae. Striate band well developed. Comb VIII with toothed margin. Female squama genitalis with pointed acrostyli.

Type species. Acerentulus australiensis Womersley, 1932.

Distribution. Australia, New Zealand, Tropical Asia, Madagascar.

Remarks. For a key to the identification of Australentulus species, see François (1994).

16 – Baculentulus Tuxen, 1977

Labial palps reduced to two or three setae and a sensillum. Canal of maxillary glands simple, without appendages, with heart-shaped calyx. Foretarsal sensillum t1 baculiform; t3 jar-shaped; b’ present or absent. Abd. app. II–III each with two setae, the median apical very short, less than half the length of the subapical. Seta P3 on Tg. II–VI anterior to other P-setae row. St. VIII with 4/0 setae. Abd. VIII with reduced striate band. Comb VIII more or less oblique. Female squama genitalis with pointed acrostyli.

Type species. Berberentulus becki Tuxen, 1976.

Distribution. Cosmopolitan.

Remarks. A recent key to the species of genus Baculentulus with foretarsal sensillum b’ is available in Bai & Bu (2013).

17 – Berberentulus Tuxen, 1963

Labial palps reduced to two or three setae and a willow leaf-shaped or sausage-like sensillum. Maxillary palps with two sensilla. Canal of maxillary glands simple, with heart-shaped calyx and long or short proximal part, rarely with excrescences. Pseudoculi circular or oval. Foretarsal sensillum t1 claviform; t3 shaped as a willow leaf, or as a small jar or, sometimes, as a rounded knob; d very close to c; b’ usually missing. Empodium short. Abd. app. II–III each with two setae, the median apical less than 1/3rd the length of the subapical. Seta P3 on Tg. II–VI placed anteriorly to the row of the other P-setae. St. I–VII with three A-setae; St. VIII with 4/0 setae. Abd. VIII with reduced striate band formed by two rather close transverse lines, the more distal serrated, the proximal one more or less undulated with small teeth pointing backwards. Subcuticular parallel tubes are visible in correspondence to the missing striae. Comb VIII reduced with very small dispersed teeth. Female squama genitalis with long pointed acrostyli and broad styli.

Type species. Acerentulus berberus Condé, 1948.

Distribution. Cosmopolitan.

Remarks. For figures and keys to the species of genus Berberentulus, see Tuxen (1977b), Chao and Chen (1999).

18 – Bolivaridia Bonet, 1942

Labial palps reduced to two setae and a sensillum. Maxillary palps with slender willow leaf-shaped sensilla. Canal of maxillary glands with heart-shaped calyx; the short proximal part with distinct lateral protuberance and with an ending “head of femur”-shaped dilation. Pseudoculi longitudinally divided, somewhat broader than long. Foretarsal sensillum t1 claviform; a’ sword-shaped; a and e long and broad, spindle-shaped. Abd. app. II–III each with a single subapical seta. Tg. II–VI with Ac seta. St. I–VII with three A-setae; St. VIII with 4/0 setae. Striate band on abd. VIII reduced, with only short, blind striae extending from the posterior margin. Comb VIII concave, with small teeth. Female squama genitalis with long, broad and pointed acrostyli; basal apodeme short.

Type species. Bolivaridia perissochaeta Bonet, 1942.

Distribution. Pantropical.

Remarks. For a recent key to Bolivaridia species, see Bu and Palacios-Vargas (2012).

19 – Brasilentulus Nosek, 1973

Labrum slightly prolonged into a rostrum. Labial palps reduced to three setae and a sensillum. Maxillary palps with two setiform sensilla. Canal of maxillary glands with heart-shaped calyx and long proximal part. All foretarsal sensilla present; long spindle-shaped sensillum t3; t1 claviform (in B. huetheri Nosek the distal half bent forwards in a rather sharp angle); b placed close to c. Abd. app. II–III each with a long subapical seta and a short apical one (1/3rd of the subapical). St. I–VII with three A-setae. St. VIII with 4/0 setae. Striate band complete. Comb VIII with teeth. Female squama genitalis with slender and pointed acrostyli.

Type species. Brasilentulus huetheri Nosek, 1973.

Distribution. Tropical America and Africa.

Remarks. Figures and a key to the species are available in Tuxen (1979).

20 – Brasilidia Nosek, 1973

Labial palps reduced to three setae and a sensillum. Maxillary palps with two setiform sensilla. Canal of maxillary glands with heart-shaped calyx and relatively short proximal part, proximally tripartite. Pseudoculi longitudinally divided with short posterior fork-shaped prolongation. On the head seta l3 is absent; seta d6 (formerly “additional”) present. Foretarsal sensillum d situated nearer to c than to e (but not very close to c); b’ present; t1 distinctly clavate (nearly “baculiform”); t3 relatively long, cylindrical; setae β1 and δ4 not differentiated (of same shape as δ1δ3). Seta P2a on meso- and metanotum nearer to P3 than to P2; P4a on metanotum not modified (of “normal” shape). Abd. app. II–III each with three setae. Seta P3 on Tg. II–V anterior to other P-setae row. St. VIII with 4/0 or 4/2 setae. Modified setae (meaning accessory setae on nota, Tg. and St. I–VII, and modified setae on head and on thoracic sterna) uniform over the whole body, as small, hair-like microchaetae. Striate band on abd. VIII reduced (with no distinct striae but just signs of them). Comb VIII with fine teeth. Female squama genitalis tripartite with pointed acrostyli.

Type species. Brasilidia tropica Nosek, 1973.

Distribution. South America.

Remarks. Figures and a recent key to the species are provided by Szeptycki and Bedano (2003).

21 – Chosonentulus Imadaté & Szeptycki, 1976

Labial palps reduced to three setae and a broad sensillum. Canal of maxillary glands with racemose appendices, its proximal part rather short. Foretarsal sensillum t1 filiform; b in row with c; d close to c; e nearer to f than to d. Abd. app. II–III each with two setae, the apical one nearly half the length of the subapical. Striate band on abd. VIII reduced, with no distinct striae (but a minute serration is present near its anterior edge). Seta P3 on Tg. II–VI anterior to other P-setae row. St. VIII with 4/0 setae. All the tergal accessory setae sensilliform. Female squama genitalis with pointed acrostyli.

Type species. Chosonentulus chosonicus Imadaté & Szeptycki, 1976.

Distribution. Korea and China (after Wu and Yin 2008).

Remarks. For figures, see Imadaté and Szeptycki (1976), Wu and Yin (2008).

22 – Delamarentulus Tuxen, 1963

Rostrum slightly developed. Labial palps reduced to an apical and two lateral setae and a setiform curved sensillum. Sensilla of maxillary palps setiform. Canal of maxillary glands with long and slender calyx; the proximal part long. Pseudoculi with divided lid; posterior prolongation very small. All foretarsal sensilla present; t3 very long, lancet-like; t1 claviform [in D. pachychaetus Tuxen and D. tristani (Silvestri) the distal half bent forwards in a rather sharp angle]. Abd. app. II–III each with an apical seta nearly 1/3rd the subapical length. St. I–VII with three A-setae; St. VIII with 4/0 setae. Striate band complete. Comb VIII slightly concave with teeth of medium length. Female squama genitalis prolonged with very long, slender and pointed acrostyli.

Type species. Acerentulus tristani Silvestri, 1938.

Distribution. Tropical America and Africa.

Remarks. Figures and a key to the species are available in Tuxen (1979).

23 – Gracilentulus Tuxen, 1963

Labial palps reduced to three setae and a small elongated sensillum. Maxillary palps with two sensilla. Canal of maxillary glands with rather large heart-shaped calyx. Pseudoculi small, broader than long. Foretarsi with small knob-like sensillum t3 (except in G. sarmaticus Shrubovych and Szeptycki where t3 is large, subequal in length to t1); t1 claviform; a and a’ usually broader than the other sensilla (in G. sarmaticus b is broad and long as in Podolinella); b’ present or absent. Abd. app. II–III each with two setae, a median apical one very short, often only 1/5th of the subapical. Seta P3 on Tg. II–VI placed anteriorly to the row of the other P-setae. St. I–VII with three anterior setae. St. VIII with 4/0 or 4/2 (rarely) setae. Striate band well developed. Female squama genitalis with long pointed acrostyli.

Type species. Acerentulus gracilis Berlese, 1908.

Distribution. Cosmopolitan.

Remarks. Figures and a key to the species of gracilis group are available in Szeptycki (1993).

24 – Kenyentulus Tuxen, 1981

Labial palps reduced to three setae and a sensillum. Calyx smooth and proximal canal of maxillary glands with two or three beady widenings. Sensillum t1 on foretarsi baculiform; b very short. Metanotum with a small P2a seta quite close to P3. Abd. app. II–III each with a short median apical seta and a long subapical one. Seta P1a on Tg. II–VI very close to P1. St. VIII with 4/0 setae. Striate band reduced, with striae only faintly visible using phase contrast. Comb VIII with small pointed teeth. Acrostyli of female squama genitalis pointed.

Type species. Acerentulus kenyanus Condé, 1948.

Distribution. East and Tropical Asia; one species (K. kenyanus) pantropical.

Remarks. For figures, see Imadaté (1991), Yin (1999).

25 – Madagascaridia Nosek, 1978

Labial palps reduced to two setae and a sensillum. Canal of maxillary glands with heart-shaped calyx and three lobes on the distal part near calyx, proximally deeply bipartite. All foretarsal sensilla present; c and d close to each–other. Abd. app. II–III each with one seta only. Striate band on abd. VIII reduced, with strongly dispersed striae. Comb VIII with small pointed teeth. Female squama genitalis with long pointed acrostyli.

Type species. Madagascaridia condei Nosek, 1978.

Distribution. China, Madagascar.

Remarks. For figures, see Nosek (1978b) and Yin (1999).

26 – Maderentulus Tuxen, 1963

Maxillary and labial palps with tuft of setae and sausage-like sensilla (two and one, respectively). Canal of maxillary glands with long and slender calyx and short proximal part; the terminal dilation as in Acerentulus. Pseudoculi small. Foretarsal sensillum t3 bacilliform; t1 claviform; b, c and d in a row at the same level. Abd. app. II–III each with two setae, the median apical one more than half the length of the subapical. Tg. II–VI with seta P3 in anterior position to P-setae row. St. VIII with 4/2 setae. Striate band well developed. Comb VIII with toothed margin. Female squama genitalis tripartite.

Type species. Acerentulus maderensis Condé, 1957.

Distribution. Iberian Peninsula, Macaronesia, Serbia (Blesic and Mitrovski–Bogdanović, 2012).

Remarks. For figures, see Tuxen (1982).

27 – Najtentulus Szeptycki & Weiner, 1997

Sensilla of maxillary palps thick; labial palps with tuft of setae and a thick sensillum. Maxillary glands with large, smooth, nearly round calyx and short posterior filament. Foretarsal sensillum b’ present; t1 fusiform; t3 long, cylindrical; d situated proximally to the level of t2, nearer to c than to e; all sensilla of the inner side of foretarsi thick; setae β1 and δ4 short, sensilliform. Meso- and metanotum with seta P2a nearer to P3 than to P2; setae P1a, P2a and P5 oblong microchaetae; P4a on metanotum short microchaeta. Abd. app. II–III each with three setae, the lateral apical approx. twice as long as the median one. Seta P3 on Tg. II–VI anterior to line P2P4. Laterotergite VIII with peculiar, circular structure in anterior part. Tg. X with seta P1a present. St. VIII with 4/2 setae. Striate band on abd. VIII well developed, broad. Hind margin of segments IX–XII smooth. Female squama genitalis with apically situated acrostyli.

Type species. Najtentulus silvestris Szeptycki & Weiner, 1997.

Distribution. West Europe.

Remarks. For figures, see Szeptycki and Weiner (1997).

28 – Neobaculentulus Yin, 1984

Maxillary palps with two sensilla: one setiform, the other torch light-shaped. Labial palps reduced to two setae and a sensillum. Calyx of maxillary glands simple. Foretarsi with all the sensilla; a to g and a’ to c’ present; t1 baculiform; t3 short (lanceolate). Abd. app. II–III each with two setae, a long subapical and a short median apical one. Tg. II–VI often with seven pairs of P-setae, seta P1a often absent; nine pairs of P-setae on Tg. VII. St. VIII with 4/0 setae. Striate band reduced, the striae invisible. Comb VIII oblique with small teeth. Female squama genitalis with pointed acrostyli.

Type species. Berberentulus izumi Imadaté, 1965.

Distribution. Far East.

Remarks. For figures and a key to species, see Bu and Xie (2006).

29 – Notentulus Yin, 1989

Labial palps without tuft, with two to four setae and one sensillum. Maxillary glands with heart-shaped calyx with lobed distal excrescences; proximal part without dilations. Foretarsal sensillum t1 baculiform; b’ absent. Abd. app. II–III each with two setae, the lateral apical one half the length of the subapical. Tg. VII with Ac seta. St. VIII with 4/0 setae. Striate band with short, irregular striae, and arranged in a waved line. Comb oblique and slightly concave, with sparsely sharp teeth. Female squama genitalis with pointed acrostyli.

Type species. Notentulus zunyinicus Yin, 1989.

Distribution. China, Central America.

Remarks. For figures, see Yin (1999).

30 – Podolinella Szeptycki, 1995

Labial palps reduced to two lateral setae, a single terminal tuft-seta and a small claviform or oval sensillum. Maxillary glands with smooth calyx and bilobate posterior dilation. Foretarsi with a relatively large leaf-like sensillum t3; b large, passing the empodium. Notal setae short. Prosternum without seta A2. Abd. app. II–III each with two setae, the median apical seta less than half the length the subapical one. Seta P3 on Tg. II–VI anterior to line P2P4. St. I‒VII with three A-setae. St. VIII with 4/0 setae. Striate band complete. Comb VIII with 7–12 small teeth.

Type species. Podolinella podolica Szeptycki, 1995.

Distribution. Europe (after Galli et al. 2016).

Remarks. For figures, see Szeptycki (1995b).

31 – Polyadenum Yin, 1980

Rostrum short. Labial palps reduced to three setae and a thick sensillum. Proximal part of the canal of maxillary glands three-branched. Foretarsal sensillum t1 claviform; b, c and d nearly aligned; f halfway between e and g; a’ thick, situated between t1 and t2; b’ missing. Abd. app. II–III each with two setae, the apical one approx. half the length of the subapical. St. VIII with 4/0 setae. Striate band on abd. VIII reduced, with indistinct striae. Female squama genitalis with tripartite perigynium and pointed acrostyli.

Type species. Polyadenum sinensis Yin, 1980.

Distribution. China.

Remarks. For figures, see Yin (1999).

32 – Proacerella Bernard, 1975

Labial palps reduced to four setae and a sensillum. Distal end of canal of maxillary glands bulbous; faint expansions proximal to the calyx. Foretarsal sensillum t1 claviform; g nearly at the same level of t3 and of approx. the same length; b’ absent. Abd. app. II–III each with two setae, the lateral apical one more than half the subapical. St. VIII with 4/0 setae. Striate band well developed, with hook-shaped design in P. reducta Bernard (after Tuxen, 1981). Comb VIII with approx. 12 teeth. Female squama genitalis with pointed stylus, passing the apex of acrostyli.

Type species. Proacerella reducta Bernard, 1975.

Distribution. North America, West Europe.

Remarks. For figures, see Bernard (1975), Aldaba (1983).

33 – Silvestridia Bonet, 1942

Labial palps reduced to two or three setae and a sensillum. Sensillum of maxillary palps willow leaf-shaped. Canal of maxillary glands with heart-shaped calyx and short or longer proximal part not exceeding the proximal branch of the fulcrum; more or less bipartite in the proximal part. Pseudoculi circular with fork-shaped prolongation. All sensilla present on foretarsi; t1 claviform; t3 willow leaf-shaped; a’ shaped as an old Roman vase, close to t1; b spindle-shaped, reaching seta γ4. Seta P3 on Tg. II–VI is slightly anterior to the other P-setae. Abd. app. II–III each usually with one seta only, the subapical one (rarely also a delicate median apical seta is present). St. I–VII with three A-setae; St. VIII with 4/0 setae. Striate band on abd. VIII reduced, with distinct dispersed striae proceeding from the proximal border. Comb VIII concave with small teeth. Female squama genitalis with relatively short apodeme and long pointed acrostyli.

Type species. Silvestridia artiochaeta Bonet, 1942.

Distribution. Pantropical.

Remarks. For figures, see Tuxen (1980), Yin and Dallai (1985).

34 – Tasmanentulus Tuxen, 1985

Labial palps reduced to four setae and a sensillum. Canal of maxillary glands with heart-shaped calyx, sometimes with distal dilations of variable size and shape. Sensillum t1 on foretarsi claviform; t3 more or less parallel-sided; d closer to c than to e; b’ present or absent. Abd. app. II–III each with two setae, the lateral apical one more than half as long as the subapical. Striate band partly reduced (the striae may be seen more or less distinctly, but never as distinct) with hook-shaped design. St. VIII with 4/2 setae. Comb VIII with fairly large teeth. Female squama genitalis with small pointed acrostyli.

Type species. Gracilentulus tasmanicus Tuxen, 1967.

Distribution. Australia, New Zealand.

Remarks. For figures and a key to species, see Tuxen (1986).

35 – Tuxenidia Nosek & Cvijović, 1969

Labial palps reduced to three setae and remnant of terminal tuft, composed of a bifurcate seta. Maxillary palps of medium length; sensilla equal, long, thin, almost setiform. Canal of maxillary glands with oval, smooth calyx. Foretarsi with baculiform sensillum t1; t3 long, nearly cylindrical; e closer to f than to d; c halfway between d and b; b’ present; setae β1 and δ5 shorter than other setae of “δ” group, resembling sensilla; δ5 proximal to c’. Setae P1a and P2a on meso- and metanotum developed as gemmate microchaetae. Prosternum with two A-setae (A2 present). Abd. app. II–III each with one or two setae. Seta P3 on Tg. II–VI anterior to other P-setae line. Accessory setae on abd. II–VII shorter than 1/5th the length of the main setae, setiform on both Tg. and St. Striate band on abd. VIII well developed, with strong striae and distinct, granulated anterior line. Comb VIII with convex hind margin. Hind margin of segments IX–XII smooth. Female squama genitalis with knob-like acrostyli.

Type species. Tuxenidia balcanica Nosek & Cvijović, 1969.

Distribution. Balkans, Near East.

Remarks. For figures and comparative diagnosis of Tuxenidia spp., see Szeptycki and Broza (2004).

36 – Vindobonella Szeptycki & Christian, 2001

Labial palps without tuft, with three setae and one long, thick, parallel-sided sensillum. Calyx of maxillary glands ovoid, smooth. Head with sd4 seta. Foretarsi with sensillum b’; d nearer to c than to e; t1 claviform; t2 spindle-like; t3 cylindrical. Seta P2a on meso- and metanotum nearer to P3 than to P2. Abd. app. II–III each with a median apical seta less than half the length of the subapical. Seta P3 on Tg. II–VI anterior to line P2P4. St. VIII with 4/0 setae. Striate band on abd. VIII well developed. Comb VIII with straight hind margin and nearly ten slender teeth. Female squama genitalis short, with short subapical bidentate acrostyli.

Type species. Vindobonella leopoldina Szeptycki & Christian, 2001.

Distribution. Austria.

Remarks. For figures, see Szeptycki and Christian (2001).

37 – Yinentulus Tuxen, 1985

Labial palps reduced to three setae and a sausage-shaped sensillum. Maxillary palps with tuft of setae and two pointed sensilla. Canal of maxillary glands with heart-shaped calyx, distal extensions and the proximal part less than half as long as proximal branch of fulcrum. The head in profile has a prominent “front”. All foretarsal sensilla present; t1 baculiform; t3 expanded distally; sensillum b distal to c–d, extremely long. Abd. app. II–III each with two setae, the lateral apical one shorter than the subapical. Striate band on abd. VIII reduced. Comb VIII with many very small teeth. Female squama genitalis with pointed acrostyli.

Type species. Yinentulus paedocephalus Tuxen, 1986.

Distribution. New Zealand.

Remarks. For figures, see Tuxen (1986a).

38 – Zangentulus Yin, 1983

Labial palps reduced to two setae and a sensillum. Canal of maxillary glands with smooth and simple kidney bean-shaped calyx; end of proximal canal slightly tripartite. Pseudoculi circular. Foretarsal sensillum t1 claviform; b’ present; all the exterior sensilla extremely long. Abd. app. II–III each with two setae, the median apical one less than half the length of the subapical. Striate band on abd. VIII well developed, with striae slightly varied in shape and length. Comb VIII with straight posterior margin. Female squama genitalis with pointed acrostyli.

Type species. Zangentulus sinensis Yin, 1983.

Distribution. China.

Remarks. For figures, see Yin (1999).

Subfamily Acerentominae Silvestri, 1907

Maxillary palps with apical tuft of setae and two basal sensilla. Labial palps generally well developed with tuft of setae, two or three distinct setae and one sensillum. Meso- and metanotum each with two pairs of A-setae, or three pairs of A-setae on the mesonotum and four on the metanotum. Striate band well developed or reduced.

39 – Acerentomon Silvestri, 1907

Labrum almost always prolonged into a rostrum. Labial palps with tuft of setae, three setae and one sensillum lancet-like or knife-shaped. Calyx of maxillary glands simple, small; short proximal part. Foretarsal sensillum t1 claviform; t2 long, setiform; t3 leaf-like, large; b’ absent; a’ displaced distally, close to c’ and δ5; f and g close to each other; b and c at the same level; very long seta δ4 which contrasts with the length of other δ-setae. Three pairs of A-setae (A2, A3, A4) on the mesonotum and four pairs (A2, A3, A4, A5) on the metanotum. Abd. app. II–III each with two setae (the median apical seta less than half the length of the subapical one) or with only the subapical seta in one case (A. aceris Rusek). Seta P3 on Tg. II–VI on the same row of the other P-setae. St. VIII with 4/0 or 4/2 setae. Striate band on abd. VIII complete with distinct striae. Comb VIII with in most cases 12–14 long and strong teeth. Pleural pectines present on segments VI–VII and, exceptionally, on V. Seta x sometimes present on Tg. VII between A4 and P4. Female squama genitalis with long, pointed acrostyli (bipartite in A. balcanicum Ionescu).

Type species. Acerentomon doderoi Silvestri, 1907.

Distribution. West Palearctic.

Remarks. Figures and a recent key to the species belonging to the “doderoi” group are given by Shrubovych et al. (2016).

40 – Filientomon Rusek, 1974

Labial palps with tuft of setae, two setae and one foliaceous sensillum. Canal of maxillary glands with a racemose appendix on the calyx. Pseudoculi broader than long. Foretarsal sensillum t1 filiform; t2 setiform; t3 lanceolate; a’ between t1 and t2; not modified setae β1 and δ4. Three pairs of A-setae (A2, A3, A4) on mesonotum and four pairs of A-setae (A2, A3, A4, A5) on metanotum. Abd. app. II–III each with two setae of equal length (lateral apical and subapical) or with only the subapical seta in F. qianshanense Bu & Xie. Seta P3 on Tg. II–VI in line with other P-setae. St. VIII with 4/0 setae. Striate band well developed. Comb VIII with 10-20 teeth of slightly irregular size; the posterior margin rounded, distinctly protruding backward. Abd. II–VIII with minute pleural pectines and weak rotary wheels. Micro-teeth (often indistinct) along the hind margin of Tg. VIII–XI. Female squama genitalis with long pointed acrostyli.

Type species. Acerentulus lubricus takanawanus Imadaté, 1956.

Distribution. Far East, Siberia, North America.

Remarks. For figures and a key to species, see Bu and Xie (2007).

41 – Fjellbergella Nosek, 1978

Canal of maxillary glands similar to that of Acerentomon. Foretarsal sensillum t1 spatulate; t3 finger-shaped; b and c on different levels; d near to t2; b’ present. Meso- and metanotum each with two pairs of A-setae (A2, A4). Abd. app. II–III each with three setae different in length. Seta P3 on Tg. II–VI situated in anterior position. St. VIII with 4/2 setae. Striate band on abd. VIII reduced as in Berberentulus. Comb VIII rectangular with 10 slender teeth. Female squama genitalis with long pointed acrostyli.

Type species. Fjellbergella tuxeni Nosek, 1980.

Distribution. Alaska, Russian Far East (after Bu et al. 2014).

Remarks. For figures, review and a key to species, see Shrubovych and Bernard (2013) and Bu et al. (2014).

42 – Huashanentulus Yin, 1980

Labial palps with tuft of setae, three distinct setae and a large sensillum. Maxillary glands of the Acerentulus-type, with a smooth, simple enlarged calyx; the proximal part long, with a terminal dilation. Pseudoculi circular, enclosed in an elliptical cavity. Foretarsal sensillum t1 filiform; t1, b and c at the same level; d distal to t2; e near to d; a’ between the level of t1 and t2; b’ missing; c’ proximal to t3. Meso- and metanotum each with two pairs of A-setae (A2, A4). Seta P3 on Tg. II–VI situated anterior to other P-setae row. Abd. app. II–III each with two setae, the lateral apical one longer than half the subapical. St. I–VII with three A-setae. Striate band on abd. VIII well developed. Comb VIII slightly protruding backwards.

Type species. Huashanentulus huashanensis Yin, 1980.

Distribution. China.

Remarks. For figures and a key to species, see Bu and Yin (2010).

43 – Orinentomon Yin & Xie, 1993

Labial palps with tuft of setae, two or three distinct setae and a thick sensillum. Canal of maxillary glands relatively short, the ellipsoidal calyx with smooth, elliptic appendix on its dorsal side. Foretarsal sensillum t1 claviform; t2 setaceous; t3 lanceolate; a’ approx. at the same level of t1; b’ absent. Mesonotum with three pairs of A-setae (A2, A3, A4), metanotum with four pairs of A-setae (A2, A3, A4, A5). Abd. app. II–III each with two setae, the lateral apical one longer than half the subapical. Seta P3 on Tg. II–VI in line with other P-setae. St. VIII with 4/2 setae. Striate band on abd. VIII well developed. Comb VIII with irregular teeth. Female squama genitalis with sharp acrostyli.

Type species. Orinentomon sinensis Yin & Xie, 1993.

Distribution. Alaska, China.

Remarks. For figures, see Nosek (1980) and Yin (1999).

44 – Sugaentulus Imadaté, 1978

Labial palps with tuft of setae. Calyx of maxillary glands simple or slightly granulated with an extra appendix; posterior filament short with apical dilation. Foretarsal sensillum t1 claviform; t2 thin; t3 small, lanceolate; b and c nearly at the same level; d fairly close to e, a bit proximal respect to seta γ3; f and g very close to each other; a’ fairly distal to t1, at approx. the same level of t2; b’ absent; seta β1 short. Meso- and metanotum each with two pairs of A-setae (A2, A4). Abd. app. II–III each with two setae, the median apical one 2/3rd the length of the subapical. Seta P3 on Tg. II–VI a little anterior to the line of P-setae; all accessory setae very short, sensilliform. St. I–VII with three A-setae. St. VIII with 4/2 setae. Striate band on abd. VIII well developed, with distinct striae. Comb VIII with straight hind margin, not protruding posteriorly and nearly 20 small regular teeth. Female squama genitalis with stout apically bipartite acrostyli.

Type species. Sugaentulus masumii Imadaté, 1978.

Distribution. Japan, Russia (Siberia) (after Shrubovych and Rusek, 2010).

Remarks. For figures and the distinction between the two known species, see Shrubovych and Rusek (2010).

45 – Tuxenentulus Imadaté, 1973

Labial palps with tuft of setae. Canal of maxillary glands with globular calyx; the proximal part relatively short. Foretarsal sensilla similar to those of Acerentulus both for shape and position; a’ close to t2; b’ present; t1 claviform. Meso- and metanotum each with two pairs of A-setae (A2, A4). Abd. app. II–III each with two setae, the median apical one 2/3rd the length of the subapical. Seta P3 on Tg. II–VI slightly anterior to the other P-setae. Striate band on abd. VIII reduced as in Berberentulus. Comb VIII square, not oblique. Pleural pectines and rotary wheels on abd. present, but sometimes indistinct. Female squama genitalis with pointed acrostyli.

Type species. Tuxenentulus ohbai Imadaté, 1973.

Distribution. Northeast Asia, North America.

Remarks. For figures and a key to species, see Shrubovych and Bernard (2013).

46 – Wenyingia Imadaté, 1986

Labial palps with tuft of setae, and a slender sensillum. Canal of maxillary glands simple, smooth, calyx not globular. Foretarsi with all sensilla; t1 filiform; t3 slender and rounded apically; c and b at approx. the same level; d closer to c than to e, a bit more proximal than t2; a’ slightly distal to t1; b’ present, at approx. the same level of δ3. Meso- and metanotum each with two pairs of A-setae (A2, A4). Abd. app. II–III each with two setae, the lateral apical one strong and longer than half the subapical. On Tg. II–VI seta P3 a little anterior to the line of other P-setae; all accessory setae very short, sensilliform. St. I–VII with three A-setae; St. VIII with 4/2 setae. Striate band on abd. VIII reduced. Comb VIII not protruding posteriorly. Female squama genitalis stout, with pointed acrostyli.

Type species. Yinentulus kurosawai Imadaté, 1986.

Distribution. Japan.

Remarks. For figures, see Imadaté (1986b)

47 – Yamatentomon Imadaté, 1964

Labrum slightly prolonged. Labial palps with tuft of setae and slender or broad sensillum. Canal of maxillary glands unbranched with heart-shaped smooth calyx and with a helmet-like dorsal appendix. Pseudoculi elevated on the surface, longitudinally divided with distinct posterior fork-shaped prolongation. Foretarsal sensillum b long; d placed halfway between c and e or closer to e; f and g very close to each other; t1 baculiform; t3 lancet-like; a’ long, close to t1; b’ absent. Three pairs of A-setae on the mesonotum (A2, A3, A4) and four pairs on the metanotum (A2, A3, A4, A5). Abd. app. II–III each with two setae (lateral apical seta slightly shorter than subapical one). Seta P3 on Tg. II–VI in line with other P-setae. Tg. II–VII with eight or more A-setae; Tg. VIII with six A-setae. St. II–VII with five or more A-setae; St. VIII with 4/0 setae. Striate band on abd. VIII well developed. Comb VIII convex, with very fine teeth. Posterior border of abd. VIII–IX with very fine teeth. Pleurite VIII with lateral pectines. Female squama genitalis with long pointed acrostyli.

Type species. Acerentulus yamato Imadaté & Yosii, 1956.

Distribution. Far East (Japan, Korea, northeastern China and Russian Far East).

Remarks. Figures and a key to species are available in Bu and Wu (2012).

48 – Yichunentulus Yin, 1980

Labial palps with one-branched terminal tuft of setae, three setae and a sensillum. Maxillary glands simple and without appendages. Foretarsal sensillum t1 baculiform; t3 short, lanceolate; sensillum b’ absent or present; a’ located distal to t1. Meso- and metanotum each with two pairs of A-setae (A2, A4). Abd. app. II–III each with two setae, the median apical one approx. half the length of the subapical. Seta P3 on Tg. II–VI anterior to other P-setae row. St. II–VI with three A-setae; St. VIII with 4/2 setae. Striate band on abd. VIII reduced as in Berberentulus. Comb VIII with 10-12 small teeth. Female squama genitalis with pointed acrostyli.

Type species. Yichunentulus yichunensis Yin, 1980.

Distribution. China.

Remarks. For figures and a key to species, see Bu et al. (2014).

49 – Liaoxientulus Wu & Yin, 2011

Head without differentiated sensory setae. Postpseudocular (sd4) seta present. Labial palps reduced, with three setae and no sensillum. Canal of maxillary glands simple, with smooth, ovate calyx and long, simple posterior filament. Pseudoculi nearly circular. All foretarsal sensilla present; dorsal sensillum t1 claviform; t2 thin and pointed; t3 broad jar-shaped; c and d close to each other; f distinctly nearer to e than to g; a’ slightly proximal to t1; b’ at approx. the same level of δ3; ventral seta β1 and interior seta δ4 both short and sensilliform. Meso- and metanotum each with two pairs of A-setae (A2, A4); seta P2a nearer to P3 than to P2. Abd. app. II–III each with two setae, the lateral apical one more than half as long as the subapical. On Tg. II–VI seta P3 slightly anterior to other P-setae row; accessory setae very short, sensilliform. St. I–VII with three A-setae; St. VIII with with 4/2 setae. Striate band on abd. VIII, not fully developed. Comb VIII with eight irregular teeth. Female squama genitalis with long pointed acrostyli.

Type species. Liaoxientulus xingchengensis Wu & Yin, 2011.

Distribution. China.

Remarks. For figures, see Wu and Yin (2011).

Subfamily Nipponentominae Yin, 1983

Labial palps fully developed with tuft of setae. Maxillary glands with two racemose appendices or a distinct vesicle on the calyx. Meso- and metanotum each with two pairs of A-setae, or three pairs of A-setae on the mesonotum and three or four pairs of A-setae on the metanotum. Abd. app. II–III each with two setae. Striate band on abd. VIII well developed.

50 – Alaskaentomon Nosek, 1977

Labial palps with a sensillum. Canal of maxillary glands with verrucose appendices on calyx and helmet-like dilation on the cover. Foretarsal sensillum a extraordinarily long, reaching seta γ4; t1 filiform. Meso- and metanotum each with two pairs of A-setae (A2, A4). Lateral apical and subapical seta on abd. app. II–III nearly of equal length. Tg. II–VI with eight A-setae. Seta Pc present on Tg. VII and St. VI–VII. St. VIII with 4/2 setae. Striate band on abd. VIII with fine serrated line anteriorly and well developed striae posteriorly. Comb VIII with 10-15 teeth.

Type species. Alaskaentomon fjellbergi Nosek, 1977.

Distribution. Alaska.

Remarks. For a recent revision of genus Alaskaentomon, see Shrubovych et al. (2014c).

51 – Callientomon Yin, 1980

Labial palps with a broad sensillum. Canal of maxillary glands with enlarged calyx, decorated with radiate–rods appendices and an extra–appendix on the cover. Pseudoculi circular. Foretarsal sensillum t1 filiform; b’ absent. Pronotum with three pairs of setae (1, 1’, 2). Meso- and metanotum each with three pairs of A-setae (A2, A3, A4). Lateral apical seta on abd. app. II–III longer than half the subapical. St. VIII with 4/2 setae. Comb VIII with curved hind margin and approx. 20 small, slender teeth. Female squama genitalis with pointed acrostyli.

Type species. Callientomon chinensis Yin, 1980.

Distribution. China.

Remarks. For figures, see Yin (1999) and Shrubovych (2014).

52 – Imadateiella Rusek, 1974

Labial palps with two lateral setae and a foliaceous sensillum. Pseudoculi almost circular or broader than long. Canal of maxillary glands with racemose appendices on the calyx and, usually, an additional appendix on the cover. Foretarsal sensillum t1 spindle-shaped; t2 thin and long; t3 lanceolate; b’ absent. Mesonotum with three pairs of A-setae (A2, A3, A4), metanotum with four pairs of A-setae (A1, A2, A3, A4). Mesosternum with five A-setae; metasternum with seven A-setae. Lateral apical seta on abd. app. II–III longer than half the subapical. Five pairs of A-setae on Tg. II–VI; four pairs of A-setae on Tg. VII. Seta P3 on Tg. II–VI on the same row of the other P-setae. St. I–VII with three A-setae. St. VIII with 4/0 setae. Posterior margin of comb VIII not protruding backward. Abdominal pectinated structures as pleural pectines visible, but often indistinct. No teeth on the hind margin of St. IX–XI. Female squama genitalis with long pointed (or bipartite) acrostyli.

Type species. Acerella shiria Imadaté, 1964.

Distribution. East and Central Asia.

Remarks. Figures and a recent key to species are available in Shrubovych et al. (2015).

53 – Nienna Szeptycki, 1988

Maxillary palps with basal sensilla equal, thin, nearly setiform. Labial palps with a broad sensillum. Calyx of maxillary glands with small granulated appendices. Pseudoculi circular, with short lever. Foretarsal sensillum b’ missing; t1 filiform; t3 globular; b and c nearly at the same level; d nearer to e than to c; a’ more proximal than t2; setae β1 and δ4 of normal shape, subequal to setae δ1–δ3. Meso- and metanotum each with three pairs of A-setae (A2, A3, A4); seta P2a on nota nearer to P3 than to P2. Prosternum without seta A2. Lateral apical and subapical seta on abd. app. II–III nearly of equal length. Seta P3 on Tg. II–VI in line with other P-setae. St. VIII with 4/2 setae. Hind margin of comb VIII straight. St. IX–X with traces of striate band. Hind margin of Tg. X–XI with subtle serration. Female squama genitalis with short, pointed acrostyli.

Type species. Nienna parvula Szeptycki, 1988.

Distribution. Central Asia, Northwest China (after Bu & Yin, 2008).

Remarks. For figures, see Szeptycki (1988).

54 – Nipponentomon Imadaté & Yosii, 1959

Labrum prolonged into a short rostrum. Labial palps with three setae and a foliaceous sensillum. Canal of maxillary glands with verrucose calyx, often produced into side-flaps, the proximal part usually long and with long proximal dilation. Pseudoculi small, usually, broader than long. Foretarsal sensillum t1 long and spindle-shaped; t3 long, lancet-like; d close to e; b and c subequal in length; a’ a little bit more distal than t2; b’ missing. Mesonotum with three pairs of A-setae (A2, A3, A4); metanotum with four pairs of A-setae (A1, A2, A3, A4). Lateral apical and subapical seta on abd. app. II–III of equal length. Tg. I–VI with 8–10 A-setae. Seta P3 on Tg. II–VI on the same row of the other P-setae. St. I–VI with three to five A-setae; VII with three A-setae; VIII with 4/2 setae. Comb VIII with approx. ten long and strong teeth. Posterior margin of abd. IX–XI with pectinated structures. Pleural pectines often present on segments II–VIII. Female squama genitalis with mostly square acrostyli with uneven apex or produced into three teeth; sometimes, long and pointed acrostyli.

Type species. Acerentomon nippon Yosii, 1938.

Distribution. Northeast Asia, North America.

Remarks. For a key to species, see Bu et al. (2013).

55 – Noldo Szeptycki, 1988

Maxillary palps with equal, thin and nearly setiform basal sensilla. Labial palps with broad leaf-like sensillum. Calyx of maxillary glands small, granulated; posterior filament with granulated thikening. Pseudoculi circular, with relatively long lever. Foretarsal sensillum b’ missing; a’ slightly more proximal than t2; t1 filiform; t3 leaf-like; b and c nearly at the same level; d nearer to e than to c; setae β1 and δ4 sensillum-shaped. Meso and metanotum each with three pairs of A-setae (A2, A3, A4); seta P2a on nota nearer to P3 than to P2. Prosternum with seta A2 present. Lateral apical and subapical seta on abd. app. II–III nearly of equal length. Seta P3 on Tg. II–VI in line with other P-setae. St. VIII with 4/2 setae. Comb VIII with straight hind margin. Abd. IX–X without striate band. Hind margin of Tg. X–XI with very subtle serration. Female squama genitalis with relatively short, pointed acrostyli.

Type species. Noldo submontanus Szeptycki, 1988.

Distribution. Russia and Ukraine (Crimea).

Remarks. For figures and the distinction between the two known species of genus Noldo, see Shrubovych and Szeptycki (2006).

56 – Nosekiella Rusek, 1974

Labial palps with a broad sensillum. Canal of maxillary glands with two racemose appendices on the calyx and an additional appendix on the cover. Pseudoculi broader than long. Foretarsi with baculiform sensillum t1; t2 long, setiform; t3 lanceolate; a’ at the same level of or anterior to t2 base. Meso- and metanotum each with three pairs of A-setae (A2, A3, A4). Lateral apical and subapical seta on abd. app. II–III nearly of equal length. Seta P1a present on Tg. I–VI. Tg. II–VI with 10 A-setae; Tg. VIII with four or six A-setae. Prosternum with or without seta M2. St. III with five P-setae; St. I–VII with three A-setae; St. VIII with 4/0 or 4/2 setae. Pleural pectines visible. Hind margin of segments IX–XI smooth. Female squama genitalis short, with blunt, bilobed acrostyli.

Type species. Acerentulus danicus Condé, 1947.

Distribution. Palearctic (after Shrubovych et al., 2014).

Remarks. For a recent revision of genus Nosekiella, see Shrubovych et al. (2014a).

57 – Paracerella Imadaté, 1980

Maxillary and labial palps with tuft of setae and two and one sensilla, respectively. Maxillary glands with distinct calyx with racemose appendices on its surface. Foretarsal sensillum t1 filiform; sensillum d placed at approx. halfway between c and e or a little closer to e; a’ fairly distal to t1, at approx. the same level of t2. Meso- and metanotum each with three pairs of A-setae (A2, A3, A4). Subapical seta on abd. app. II–III slightly longer than lateral apical. Seta P3 on Tg. II–VI in line with other P-setae. St. I–VII with three A-setae. St. VIII with 4/0 or 4/2 setae. Comb on abd. VIII with irregular teeth.

Type species. Acerella shirataki Imadaté, 1964.

Distribution. China (after Bu et al., 2016), Japan and North America.

Remarks. Figures and a key to species are provided in Shrubovych and Smykla (2012).

58 – Verrucoentomon Rusek, 1974

Labial palps with a four-branched terminal tuft and a sensillum. Maxillary glands with racemose surface of calyx and without wide racemose appendices. Foretarsal sensillum t1 filiform; t3 leaf-like; d near e; a’ at the level or distal to the base of t2; seta β1 setiform; δ4 short and blunt. Meso- and metanotum each with three pairs of A-setae (A2, A3, A4). Lateral apical and subapical seta on abd. app. II–III nearly of equal length. Five pairs of A-setae on Tg. II–VI; seta P3 in line with other P-setae. St. VIII with 4/0 or 4/2 setae. Comb on abd. VIII with distinct teeth.

Type species. Acerella kawakatsui Imadaté, 1964.

Distribution. Central and East Asia, Central Europe, North America.

Remarks. Figures and a key to species are provided in Shrubovych and Bernard (2012). For a recent review of the North American species, see Shrubovych et al. (2015).

59 – Nanshanentulus Bu & Yin, 2007

Maxillary palps with two sensilla, parallel-sided and equal in length. Labial palps with tuft of setae and a broad sensillum. Calyx of maxillary glands with two lateral racemose appendices and with posterior filament slightly split into two leaves. Pseudoculi ovate. Foretarsi with no sensillum b’; t1 claviform; t3 small and lanceolate; c slightly lower than level of b; d nearer to e than to c; c and e short and broad; a’ at the level of t1; setae β1 and δ4 of normal shape. Claw with single inner flap. Meso- and metanotum with three pairs of A-setae (A2, A3, A4); seta P2a on nota near to P3 than to P2. Prosternum with no seta A2. Subapical seta on abd. app. II–III slightly longer than lateral apical. Seta P1a on Tg. I–VI absent; seta P3 on Tg. II–VI in posterior position. St. VIII with 4/0 setae. Striate band on Tg. IX and X absent. Comb on abd. VIII with straight hind margin. Female squama genitalis robust and with short blunt acrostyli.

Type species. Nanshanentulus urumchiensis Bu & Yin, 2007.

Distribution. China.

Remarks. For figures, see Bu and Yin (2007).

60 – Vesiculentomon Rusek, 1974

Maxillary palps with two equally long spike-like sensilla; labial palps with broad sensillum. Extraordinarily large vesicle on the maxillary glands, weakly granulated along its proximal part. Pseudoculi circular. Foretarsal sensillum t1 baculiform; t2 setiform; t3 leaf-like. Mesonotum with three pairs of A-setae (A2, A3, A4); metanotum with four pairs of A-setae (A1, A2, A3, A4). Lateral apical and subapical seta on abd. app. II–III nearly of equal length. Comb on abd. VIII with 14 very small teeth. Hind margins of Tg. IX–XI and St. IX–X laterally finely serrated. Female squama genitalis short, with apically bilobed acrostyli.

Type species. Vesiculentomon marshalli Rusek, 1974.

Distribution. North America.

Remarks. Genus was recently revised by Shrubovych et al. (2014a,b).

61 – Nosekientomon Shrubovych, Rusek & Bernard, 2014

Maxillary palps with two sensilliform sensilla; labial palps with broad sensillum. Maxillary glands with two racemose appendices and a smooth globular vesicle on the calyx. Foretarsal sensillum t1 claviform; position of d midway between sensilla c and e; position of foretarsal sensillum a’ slightly distal to level of t2. Meso- and metanotum each with three pairs of A-setae (A2, A3, A4). Subapical seta on abd. app. II–III slightly longer than lateral apical one. Seta P3 on Tg. II–VI in line with other P-setae. St. I–VII with three A-setae; St. VIII with 4/2 setae. Comb on abd. VIII with 10–11 short teeth. Hind margins of abd. IX–XII smooth. Female squama genitalis short, with blunt bilobed acrostyli.

Type species. Vesiculentomon ruseki Nosek, 1977.

Distribution. North America.

Remarks. For figures, see Shrubovych et al. (2014b).

62 – Yavanna Szeptycki, 1988

Maxillary palps with thin, nearly setiform basal sensilla. Labial palps with broad basal sensillum. Pseudoculi circular, with short lever. Calyx of maxillary glands simple, large, with small granulation. Foretarsi with claviform sensillum t1; t3 leaf-like; b and c nearly at the same level; d nearer to e than to c; a’ more distal than t2; b’ absent; seta β1 of normal shape, δ4 sensillum-shaped. Meso- and metanotum each with three pairs of A-setae (A2, A3, A4); seta P2a on nota nearer to P3 than to P2. Prosternum with or without seta M2. Subapical seta on abd. app. II–III slightly longer than lateral apical. Seta P1a present on Tg. I–VII or on Tg. VII only. Tg. II–VI with 10 anterior setae and seta P3 in line with other P-setae; Tg. VIII with six A-setae (A2, A4, A5). St. I–VII with three A-setae; St. III with five or six P-setae; St. VII with or without seta Pc; St. VIII with 4/2 setae. Hind margin of comb on abd. VIII slightly convex. St. IX–X with distinct striate band. Hind margin of Tg. X–XI smooth. Female squama genitalis short, with blunt, bilobed, or three-lobed acrostyli.

Type species. Yavanna altaica Szeptycki, 1988.

Distribution. Central Asia, China.

Remarks. Figures and a key to species are given by Shrubovych et al. (2012).

Subfamily Acerellinae Yin, 1983

Labial palps with terminal tuft of setae, two setae and an oval or foliaceous sensillum. Canal of maxillary glands with lateral verrucose appendices on calyx. Meso- and metanotum each with three pairs of A-setae (A2, A3, A4). Abd. app. II–III each with two setae (lateral apical and subapical) subequal in length.

63 – Acerella Berlese, 1909

Maxillary palps with two sensilla spindle-shaped or very slender willow leaf-shaped. Pseudoculi broader than long, longitudinally divided, with distinct fork-shaped posterior prolongation. Foretarsal sensillum t1 long, filiform; t3 lanceolate, but not pointed; d usually closer to e than to c; f extremely long; b, g and a’ broad; b’ missing. Seta P3 on Tg. II–VI on the same row of the other P-setae. St. I–VII with three A-setae; St. VIII with 4/0 setae. Striate band on abd. VIII well developed. Comb VIII with distinct teeth. Female squama genitalis with rather long acrostyli.

Type species. Acerentulus tiarneus Berlese, 1908.

Distribution. West Palearctic.

Remarks. For figures, see Nosek (1973) and Shrubovych (2011).

Order SINENTOMATA Yin, 1966

Abdomen with pectinated structures. Median setae absent on meso- and metanotum. Abd. app. I always two-segmented with terminal vesicle and four setae. Female squama genitalis with long acrostyli.

Family Fujientomidae Tuxen & Yin, 1982

Pale body. Spiracles absent. Foretarsi with additional sensillum x on the external side. Abd. app. all two-segmented with four setae and terminal vesicle. Comb VIII with small teeth.

64 – Fujientomon Imadaté, 1964

Rostrum somewhat protruded. Maxillary palps with tuft of setae and two sensilla. Labial palps reduced with an apical thick seta and two basal setae. Canal of maxillary glands simple, ending with a long sac- or sausage-like dilation. Pseudoculi circular without lever. Foretarsal sensilla b’ and c’ absent; sensillum t1 extremely broad; t2 broad; t3 long and slender; exterior sensilla a and x broad, foliaceous. Empodium long, a little shorter than claw. Seta S remarkably longer than claw. Metanotum with two or three pairs of A-setae (A3 is very short, sensilliform, often absent). Tg. I–VII with seta Ac. St. VIII with 4/4 setae. Comb VIII with approx. 15 small teeth, and a few small teeth on its anterior margin. Female squama genitalis with rod-like acrostyli.

Type species. Fujientomon primum Imadaté, 1964.

Distribution. China, Japan.

Remarks. Redescription by Nakamura (2014) was followed.

Family Sinentomidae Yin, 1965

Body reddish-brown. Tracheal system present. Pseudoculi large with 7–13 transverse striae. Foretarsi with additional sensillum c” on the internal side. Abd. app. II–III uni-segmented, each with two setae, a long distal and a short proximal one. Basal part of the female squama genitalis bucket-like, with large and stout acrostyli.

65 – Sinentomon Yin, 1965

Integument highly sclerotized, pigmented in reddish-brown and covered with many scale-like portions with serrated, posterior margins. Labial palps with two setae and apical tuft. Canal of maxillary glands indistinct. Pseudoculi with transverse striation. Foretarsi with nine long and slender dorsal setae (α1–9), three dorsal filiform sensilla (t1, t2 and t3), nine ventral setae (β1–9), five external setae (γ1–5), seven external sensilla (a–g), six internal setae (δ1–6) and four internal sensilla (a’, b’, c’, c”). Meso- and metanotum each with three pairs of A-setae (A1, A2, A4). Abd. VIII with smooth combs covering openings of abdominal glands. Female squama genitalis with median palps and long and pointed acrostyli.

Type species. Sinentomon erythranum Yin, 1965.

Distribution. China, Japan, North Korea.

Remarks. For figures, see Yin (1999).

Order EOSENTOMATA Yin, 1996

Tracheal system normally present on meso- and metanotum. Foretarsus with additional setae and sensilla (e.g. x, y, z, f2, b’2). Abdomen without pectinated structures. Three pairs of two-segmented abd. app., each with terminal vesicle and five setae. Female squama genitalis with processus sternalis and without acrostyles.

Family Eosentomidae Berlese, 1909

Eosentomata with spiracles on meso- and metanotum. Pseudoculi small.

Subfamily Isoentominae Yin, 1983

Foretarsal sensilla e (if present) and g short or long, spiniform or setiform (spatulate only in genus Zhongguohentomon).

66 – Isoentomon Tuxen, 1975

Foretarsal sensilla g and e (when present) spiniform or short and setiform (never spatulate); sensillum b1’ present. Seta P1a on Tg. I–VI longer than seta P1. Female squama genitalis with “dissolved”, in most cases extremely short processus sternalis.

Type species. Eosentomon atlanticum Condé, 1947.

Distribution. Warmer areas of the whole world.

Remarks. For figures and a key to species, see Tuxen (1975).

67 – Osientomon Nakamura, 2010

Foretarsal sensillum e absent; g short and setiform; b1’ absent. On meso- and metanotum two pairs of A-setae; P2a closer to P2 than to P3. St. XII with 12 setae (a pair of small sensilliform A-setae). On female squama genitalis, processus sternalis S-shaped with caput duck’s head-like.

Type species. Osientomon japonicum Nakamura, 2010.

Distribution. Japan.

Remarks. For figures and a key to species, see Nakamura (2010).

68 – Madagascarentomon Nosek, 1978

Maxillary palps with two distinct sensilla. Labial palps with tuft of setae and a sensillum. All foretarsal sensilla, except t1, setiform; sensilla e and g long. Empodium very long. Female squama genitalis with caput processus resembling a snake’s head; stylus more than twice as long as broad; filum long.

Type species. Madagascarentomon condei Nosek, 1976.

Distribution. Madagascar.

Remarks. For figures and a key to species, see Nosek (1978b).

69 – Zhongguohentomon Yin, 1979

Integument highly sclerotized, earth-yellow coloured. Labial palps with tuft of setae, two distinct setae and a sausage-like sensillum. Central seta present on antero-dorsal surface of the head (similar to that of Sinentomon). Pseudoculi with a large triangular prolongation on the anterior margin. Foretarsal sensillum t1 clavate; t3 stout; e and g short, slightly spatulate; b1’ and b2’ present; c’ fairly long. Abd. VIII with a pair of rudimentary combs on abdominal glands. Pectinated patches on St. XI–XII. Female squama genitalis characterized by a simple stylus with a nipple-shaped processus on its posterior end and the incurvated processus filum.

Type species. Zhongguohentomon magnum Yin, 1979.

Distribution. China.

Remarks. For figures and a key to species, see Yin (1999).

Subfamily Eosentominae Berlese, 1909

Spiracles present. Foretarsal sensilla e and g both present and spatulate or clavate.

70 – Eosentomon Berlese, 1908

Canal of maxillary glands without dilation. Pseudoculi lens-like. Foretarsi with accessory setae α3’, β8, β9, δ3’ and δ4’ and extra sensilla f2, b2’, x, y, z and, rarely, c2’; sensilla e and g spatulate. Empodium long. Meso- and metanotum each with two pairs of A-setae (A2, A4). Female squama genitalis often with duck’s head-shaped caput of processus sternalis.

Type species. Eosentomon transitorium Berlese, 1909.

Distribution. Cosmopolitan.

Remarks. For figures and keys to Asian species, see Imadate (1965), Yin (1999) and Nakamura (2010). For North American species, see Allen (2007). For a key to European species, see Shrubovych and Bernard (2018).

71 – Styletoentomon Copeland, 1978

Labrum longer than mandibles and very narrow, forming a rostrum. Mandibles very long, extremely slender and sharp pointed (stylet-shaped). Canal of maxillary glands reaching prothorax. Foretarsal sensilla e and g clavate. Female squama genitalis with sharp-pointed processus sternalis and evenly bent giving a stoop-shouldered appearance.

Type species. Eosentomon rostratum Ewing, 1940.

Distribution. North America.

Remarks. For figures and diagnosis, see Copeland (1978).

Subfamily Anisentominae Yin, 1983

Spiracles present (often quite small). Foretarsal sensillum e absent; g always spatulate. Tg. II–VI with 10 or eight A-setae; eight or six A-setae on Tg. VII; St. VIII always with seven P-setae (2/7 or 0/7). Tg. X or XI of some species bearing a pair of peculiar setae or spines (Anisentomon).

72 – Anisentomon Yin, 1977

Spiracles very small. Labial palps with tuft of setae. Foretarsal sensillum g stout and spatulate. Tg. II–VII with eight A-setae. Tg. VIII with 6/9 setae (Pc present). Tg. X or XI with a pair of large spines. St. VIII with 2/7 setae (Pc present). Comb with smooth margin on laterotergite VIII. Female squama genitalis of Eosentomon type.

Type species. Eosentomon chinensis Yin, 1965.

Distribution. China.

Remarks. Xiong et al. (2008) report a key to species of genus Anisentomon.

73 – Neanisentomon Zhang & Yin, 1984

Foretarsal sensillum t2 willow leaf-shaped; f1 spindle-like; b2’ and c’ often absent; g stout and spatulate. Tg. VIII with 6/8 setae (Pc absent). St. VIII with 2/7 setae (Pc present). Female squama genitalis similar to that of Eosentomon.

Type species. Neanisentomon guicum Zhang & Yin, 1984.

Distribution. China.

Remarks. For figures and a key to species, see Bu & Yin (2011).

74 – Paranisentomon Zhang & Yin, 1984

Foretarsal sensilla f1 and t2 setiform. Tg. VIII with 6/9 setae (Pc present). St. VIII with a single row of seven P-setae (0/7). Processus sternalis often S-shaped on female squama genitalis.

Type species. Eosentomon tuxeni Imadaté & Yosii, 1959.

Distribution. China and Japan.

Remarks. For figures and a key to species, see Yin (1999).

75 – Pseudanisentomon Zhang & Yin, 1984

Foretarsal sensillum g long spatulate; t2 willow leaf-shaped or setiform; f1 spindle-shaped. Tg. VIII with 6/9 setae (Pc present). St. VIII with 0/7 or 2/7 setae. Processus sternalis often S-shaped on female squama genitalis.

Type species. Anisentomon songkiangensis Yin, 1977.

Distribution. China and Japan.

Remarks. For figures and a key to species, see Yin (1999).

Family Antelientomidae Yin, 1983

Eosentomata without open spiracles on meso- and metanotum. Sensilla on foretarsus similar to those of genus Eosentomon.

76 – Antelientomon Yin, 1974

Tg. VIII with 6/9 setae. St. VIII with Pc seta (2/7 or 2/9). Female squama genitalis similar to that of Eosentomon.

Type species. Antelientomon prodromi Yin, 1974.

Distribution. China.

Remarks. For figures and a key to species, see Yin (1999).

Key to genera

This key directly identifies genera, without intermediate steps to families and subfamilies (indicated in the diagnosis part) for greater convenience and to keep it valid regardless of the system followed. Parts concerning the Acerentominae and Nipponentominae genera are taken from Shrubovych and Rusek (2010) and Shrubovych et al. (2014b), respectively. The previous key for Acerentomidae genera by Tuxen (1984) was also used as a reference. For Protentomidae and Hesperentomidae genera, we referred to the key to subfamilies and genera by Tuxen and Yin (1982). Numbers in brackets after the names of genera indicate their position in the diagnostic section of this paper.

1 Meso- and metanotum with tracheal system and spiracles 2
Spiracles absent 13
2 Pectinated structures on the abdomen present; pseudoculi transversally striated; abdominal appendages I two-segmented, with terminal vesicle and four setae, abdominal appendages II and III unisegmented with two setae Sinentomon (65)
Abdominal pectinated structures absent; not striated pseudoculi; abdominal appendages I–III two-segmented, each with five setae 3
3 Foretarsal sensillum e absent 4
Foretarsal sensillum e present 9
4 Tergites X or XI with large spines Anisentomon (72)
Tergites X–XI without spines 5
5 Foretarsal sensillum g long, spatulate 6
Foretarsal sensillum g not long and spatulate 8
6 Tergite VIII with 6/8 setae (Pc absent) Neanisentomon (73)
Tergite VIII with 6/9 setae (Pc present) 7
7 Foretarsal sensillum f1 setiform Paranisentomon (74)
Foretarsal sensillum f1 spindle-shaped Pseudanisentomon (75)
8 Foretarsal sensillum b1’ absent Osientomon (67)
Foretarsal sensillum b1’ present Isoentomon (66 – part)
9 Foretarsal sensillum e spatulate (or clavate) 10
Foretarsal sensillum e not spatulate 12
10 Labrum long and narrow (rostrum); stylet-shaped mandibles Styletoentomon (71)
Labrum and mandibles of normal shape 11
11 Pseudoculi with a large triangular prolongation on the anterior margin Zhongguohentomon (69)
Pseudoculi lens-like Eosentomon (70)
12 Seta P1a on tergites I–VI longer than P1 Isoentomon (66 – part)
Seta P1a on tergites I–VI shorter than P1 Madagascarentomon (68)
13 Three pairs of two-segmented abdominal appendages 14
Abdominal appendages III uni-segmented 17
14 Abdominal appendages with five setae; abdominal pectinated structures absent Antelientomon (76)
Abdominal appendages with four setae 15
15 Foretarsal sensilla b’ and c’ absent 16
Foretarsal sensilla b’ and c’ present Hesperentomon (1)
16 Canal of maxillary glands with heart-shaped calyx with verrucose appendices and a proximal dilation; pseudoculi with a large triangular prolongation in the proximal part Hinomotentomon (4)
Canal of maxillary glands simple, ending with a long sac- or sausage-like dilation; pseudoculi circular without prolongation Fujientomon (64)
17 Abdominal appendages II two-segmented 18
Abdominal appendages II uni-segmented 23
18 Foretarsi with an additional sensillum c”; pseudoculi “open” posteriorly Ionescuellum (2)
Foretarsi without additional sensillum c”; pseudoculi never “open” posteriorly 19
19 Foretarsal sensilla b’ and c’ missing, t1 always present (setiform); abdominal appendages III with two or three setae 20
Foretarsal sensilla t1 and c often missing, all the other sensilla always present; abdominal appendages III always with two setae 22
20 Pseudoculi with a short lever; sternites IV–V without Pc seta Neocondeellum (6)
Pseudoculi circular without lever; sternites IV–V with Pc seta 21
21 Abdominal appendages III with two setae Paracondeellum (7)
Abdominal appendages III with three setae Condeellum (5)
22 Metanotum with only one pair of A-setae (A2); t1 usually and c always present; distinct teeth on comb on abdominal segment VIII Proturentomon (9)
Metanotum with two pairs of A-setae (A2, A4); t1 always and c sometimes missing; teeth on comb on abdominal segment VIII indistinct or missing Protentomon (8)
23 Sternite VIII with 2/4 setae Huhentomon (3)
Sternite VIII never with 2/4 setae (normally with 4/0 or 4/2 setae) 24
24 Calyx of maxillary glands granulated or racemose and/or with racemose/granulated appendices, abdominal appendages II–III each with two setae 25
Calyx of maxillary glands not as above (when weakly verrucose, abdominal appendages II–III have three setae) 40
25 Metanotum with two pairs of A-setae 26
Metanotum with three or four pairs of A-setae 27
26 Labial palps reduced, with one broad sensillum and three setae Chosonentulus (21)
Labial palps not reduced with a terminal tuft of setae and one lateral sensillum Alaskaentomon (50)
27 Metanotum with three pairs of A-setae 28
Metanotum with four pairs of A-setae 37
28 Foretarsal sensillum t1 filiform 29
Foretarsal sensillum t1 baculiform or claviform 34
29 Pronotum with three pairs of setae; maxillary glands with large vesicle bearing finger-like papillae Callientomon (51)
Pronotum with two pairs of setae; maxillary glands without papillae 30
30 Calyx of maxillary glands with small granulated appendices; foretarsal sensillum t3 globular Nienna (53)
Calyx of maxillary glands not as the one of Nienna; foretarsal sensillum t3 foliate 31
31 Foretarsal seta β1 sensilliform Noldo (55)
Foretarsal seta β1 setiform 32
32 Bases of sensilla d and a’ level with base of sensillum t2 on foretarsi Paracerella (57)
One or both of the bases of sensilla d and a’ not at the same level of sensillum t2 on foretarsi 33
33 Bases of sensilla d and a’ proximal to the base of t2 on foretarsi Acerella (63)
One or both of the bases of sensilla d and a’ distal to base of sensillum t2 on foretarsi Verrucoentomon (58)
34 Foretarsal sensillum t1 baculiform Nosekiella (56)
Foretarsal sensillum t1 claviform 35
35 Maxillary glands with smooth globular vesicle near calyx; foretarsal sensillum d central between sensilla c and e; seta 1 on sternites VIII and X short, one-third length of seta 2 Nosekientomon (61)
Maxillary glands without vesicle near calyx; foretarsal sensillum d close to e; seta 1 on sternite VIII longer than half the length of seta 2 36
36 Foretarsal sensillum a’ distal to t2 Yavanna (62)
Foretarsal sensillum a’ nearly at the same level of t1 (proximal to t2) Nanshanentulus (59)
37 Foretarsal sensillum t1 baculiform; maxillary glands with large vesicle near calyx Vesiculentomon (60)
Foretarsal sensillum t1 filiform (setiform or spindle-shaped); maxillary glands without vesicle near calyx 38
38 Sternite VIII with 4/2 setae Nipponentomon (54)
Sternite VIII with 4/0 setae 39
39 Lateral apical and subapical setae on abdominal appendages II–III of equal length (in one case only the subapical seta present); comb VIII with the posterior margin rounded and protruding backward Filientomon (40)
Lateral apical seta on abdominal appendages II–III more than half the length of the subapical; posterior margin of comb VIII not protruding backward Imadateiella (52)
40 Abdominal appendages II–III each with one seta (rarely also a delicate median apical seta is present) 41
Abdominal appendages II–III each with two or three setae 45
41 Labial palps not reduced Acerentomon (39 – part)
Labial palps reduced 42
42 Striate band well developed Tuxenidia (35 – part)
Striate band reduced 43
43 Canal of maxillary glands with heart-shaped calyx and three lobes on the distal part near calyx, proximally deeply bipartite Madagascaridia (25)
Canal of maxillary glands without lobes near calyx 44
44 Canal of maxillary glands with heart-shaped calyx, the short proximal part with a distinct lateral protuberance and terminating with a “head of femur”-shaped dilation; foretarsal sensillum a’ sword-shaped Bolivaridia (18)
Canal of maxillary glands simple with heart-shaped calyx, more or less bipartite in the proximal part; foretarsal sensillum a’ shaped as an old Roman vase Silvestridia (33)
45 Abdominal appendages II–III each with three setae 46
Abdominal appendages II–III each with two setae 52
46 Striate band reduced 47
Striate band not reduced 49
47 Foretarsal sensillum t3 knob-shaped Andinentulus (14)
Foretarsal sensillum t3 not knob-shaped 48
48 Foretarsal sensillum t3 relatively long, cylindrical Brasilidia (20)
Foretarsal sensillum t3 willow leaf-shaped Fjellbergella (41)
49 Foretarsal sensillum t3 very long (largely passing base of seta α7), cylindrical Najtentulus (27)
Foretarsal sensillum t3 not cylindrical 50
50 Foretarsal sensillum t3 lancet-like or finger-like and tapering on apex; canal of maxillary glands with proximal part ending with a row of small globules which increase in size and end with two globules placed beside each other Acerentuloides (10)
Foretarsal sensillum t3 not lancet-like or finger-like; proximal end of canal of maxillary glands without globules 51
51 Foretarsal sensillum t3 cylindrical and rounded on apex or small knob-like; sternite VIII with 4/0 setae Australentulus (15)
Foretarsal sensillum t3 willow leaf-shaped; sternite VIII with 4/2 setae Acerentulus (11)
52 Canal of maxillary glands with two or three beady widenings Kenyentulus (24)
Canal of maxillary glands without beady widenings 53
53 Labial palps not reduced, with branched tuft of setae 54
Labial palps reduced, without tuft of setae (or just a one-branched terminal tuft of setae) 61
54 Mesonotum with three pairs of A-setae and metanotum with four pairs of A-setae; sternites with five or more A-setae; seta P3 on tergites II–VI in line with other P-setae; striate band well developed 55
Mesonotum and metanotum with two pairs of A-setae; sternites with three A-setae; seta P3 on tergites II–VI slightly anterior to P-setae row; striate band well developed or reduced 57
55 Foretarsal sensillum t1 baculiform Yamatentomon (47)
Foretarsal sensillum t1 claviform 56
56 Foretarsal sensillum a’ close to t1 Orinentomon (43)
Foretarsal sensillum a’ distal to t2 and close to c Acerentomon (39 – part)
57 Striate band well developed 58
Striate band reduced 60
58 Foretarsal sensillum t1 filiform; b’ missing Huashanentulus (42)
Foretarsal sensillum t1 claviform 59
59 Foretarsal sensillum t3 long parallel-sided; b’ present Maderentulus (26)
Foretarsal sensillum t3 short lanceolate; b’ missing Sugaentulus (44)
60 Foretarsal sensillum t1 claviform; a’ close to t2 Tuxenentulus (45)
Foretarsal sensillum t1 filiform; a’ close to t1 Wenyingia (46)
61 Foretarsal sensillum t1 baculiform 62
Foretarsal sensillum t1 claviform 67
62 Foretarsal sensillum t3 long, nearly cylindrical Tuxenidia (35 – part)
Foretarsal sensillum t3 not as above 63
63 Head in profile has a prominent “front” Yinentulus (37)
Head without “front” 64
64 Maxillary palps with one setiform and one torch light-shaped sensillum; foretarsal sensillum b’ always present Neobaculentulus (28)
Maxillary palps with both sensilliform or setiform sensilla; foretarsal sensillum b’ sometimes missing 65
65 Canal of maxillary glands with excrescences Notentulus (29)
Canal of maxillary glands simple, without excrescences 66
66 Sternite VIII with 4/2 setae Yichunentulus (48)
Sternite VIII with 4/0 setae Baculentulus (16)
67 Striate band reduced 68
Striate band well developed or partly reduced (with visible parallel striae) 73
68 Foretarsal sensillum b’ present 69
Foretarsal sensillum b’ absent 71
69 Abdominal appendages II–III each with a long subapical and a very short median apical seta (< 1/3rd the length of subapical one) Berberentulus (17 – part)
Abdominal appendages II–III each with a lateral apical seta more than 1/3rd the length of the subapical one 70
70 Labial palps reduced, with three setae and no sensilla Liaoxientulus (49)
Labial palps reduced with one sensillum and three setae. Amphientulus (13)
71 Foretarsal sensillum t3 very long awl-shaped Amazonentulus (12)
Foretarsal sensillum t3 not long and shaped as a willow leaf, or a small jar or as a knob 72
72 Proximal part of the canal of maxillary glands tripartite; abdominal appendages II–III each with the median apical seta half the length of the subapical one Polyadenum (31)
Canal of maxillary glands simple, with heart-shaped calyx and “single” proximal part; abdominal appendages II–III each with the median apical seta less than 1/3rd the length of subapical one Berberentulus (17 – part)
73 Striate band partly reduced (the striae may be seen more or less distinctly, but never as distinct) with hook-shaped design; lateral apical seta on abdominal appendages II–III more than half as long as the subapical; sternite VIII with 4/2 setae Tasmanentulus (34)
Striate band well developed, without hook-shaped design (except in Proacerella reducta Bernard) 74
74 Abdominal appendages II–III each with lateral apical seta more than half as long as the subapical one; labial palps with four setae and a sensillum Proacerella (32)
Abdominal appendages II–III each with median apical seta less than half as long as the subapical one; labial palps with two or three setae and a sensillum 75
75 Labial palps with two setae and a sensillum; canal of maxillary glands with smooth and simple kidney bean-shaped calyx, the end of proximal canal slightly tripartite Zangentulus (38)
Labial palps with three setae and a sensillum; calyx of maxillary glands not kidney bean-shaped 76
76 Foretarsal sensillum t3 small and knob-like (except in G. sarmaticus Shrubovych and Szeptycki where t3 is large) Gracilentulus (23)
Foretarsal sensillum t3 long, not knob-like 77
77 Foretarsal sensillum b very long reaching or passing the empodium 78
Foretarsal sensillum b not so long 79
78 Prosternum without seta A2 Podolinella (30)
Prosternum with seta A2 Vindobonella (36)
79 Canal of maxillary glands with heart-shaped calyx Brasilentulus (19)
Canal of maxillary glands with long and slender calyx Delamarentulus (22)

Acknowledgements

We wish to thank Tony Molyneux (Gungahlin College, Canberra, Australia) for having checked and verified the English of our paper. This study was partly supported by the National Natural Sciences Foundation of China (no: 31772509) and the Natural Science Foundation of Shanghai (no: 17ZR1418700).

References

  • Aldaba J (1983) Descripción de una nueva especie de Proacerella (Protura: Acerentomidae). Actas I Congreso ibérico de Entomología 1: 13–19.
  • Allen T (2007) Studies of the North American Protura 1: cataloque and atlas of the Protura of North America; description of new species, key to the species of Eosentomon. Proceedings of the Academy of Natural Sciences of Philadelphia 156: 97–116. https://doi.org/10.1635/0097-3157(2007)156[97:SOTNAP]2.0.CO;2
  • Bai Y, Bu Y (2013) Baculentulus xizangensis sp. nov. from Tibet, China (Protura: Acerentomata, Berberentulidae) with a key to the group of Baculentulus spp. with foretarsal sensillum b’. Florida Entomologist 96(3): 825–831. https://doi.org/10.1653/024.096.0316
  • Berlese A (1908a) Nuovi Acerentomidi. Redia 5: 16–19.
  • Berlese A (1908b) Osservazioni intorno agli Acerentomidi. Nota preventiva. Redia 5: 110–122.
  • Berlese A (1909) Monografia dei Myrientomata. Redia 6: 1–182. [Pls I–XVII]
  • Bernard EC (1975) A new genus, six new species, and records of Protura from Michigan. The Great Lakes Entomologist 8: 157–181.
  • Blesić B, Mitrovski-Bogdanović A (2012) Protura in Serbia. Kragujevac Journal of Science 34: 101–106.
  • Bu Y, Ma Y, Luan YX (2016) Paracerella Imadaté in China: the description of a new species and the analysis of genetic differences between populations (Protura, Acerentomata, Nipponentomidae). ZooKeys 604: 1–11. https://doi.org/10.3897/zookeys.604.8737
  • Bu Y, Potapov MB, Yin WY (2014) Systematic and biogeographical study of Protura (Hexapoda) in Russian Far East: new data on high endemism of the group. ZooKeys 424: 19–57. https://doi.org/10.3897/zookeys.424.7388
  • Bu Y, Wu DH (2012) Revision of Chinese Yamatentomon (Protura: Acerentomata: Acerentomidae), with description of one new species, redescription of Yamatentomon yamato, and key to World species. Florida Entomologist 95(4): 839–847. https://doi.org/10.1653/024.095.0404
  • Bu Y, Xie RD (2006) Neobaculentulus heterotarsus sp. n. from Liaoning, China (Protura: Berberentulidae). Zootaxa 1188: 63–68.
  • Bu Y, Xie RD (2007) A new species of Protura from Northeast, China (Protura: Acerentomidae). Acta Zootaxonomica Sinica 32(1): 56–60.
  • Bu Y, Yin WY (2007) The Protura from Xinjang, Northwestern China. Zootaxa 1437: 29–46.
  • Bu Y, Yin WY (2008) Occurrence of Nosekiella and Nienna (Protura, Nipponentomidae) in China. Annales de la Société Entomologique de France 44(2): 201–207 .
  • Bu Y, Yin WY (2010) The Protura from Liupan Mountain, northwest China. Acta Zootaxonomica Sinica 35(2): 278–286.
  • Bu Y, Yin WY (2011) A new species of the genus Neanisentomon (Protura, Eosentomata, Eosentomidae) from Shaanxi, China. Acta Zootaxonomica Sinica 36(1): 29–32.
  • Copeland TP (1978) A new genus and two new species of Eosentomoidea (Protura, Eosentomidae). Proceedings of the entomological Society of Washington 80: 473–484.
  • Ewing HE (1921) New genera and species of Protura. Proceedings of the Entomological Society of Washington 23(9): 193–202.
  • Ewing HE (1936) Synonymy and Synopsis of the genera of the order Protura. Proceedings of the Biological Society of Washington 49: 159–166.
  • François J (1994) Une nouvelle espèce de Proture de Madagascar: Australentulus ravenalensis (Protura, Acerentomidae). Bulletin de la Société entomologique de France 99(1): 69–72.
  • Galli L, Capurro M, Costa F, Di Stadio G, Sarà A, Zinni M (2016) Redescription of two European species of Acerentomidae (Protura) belonging to the Italian fauna. Zootaxa 4154(3): 303–315. https://doi.org/10.11646/zootaxa.4154.3.5
  • Imadaté G, Yosii R (1959) A Synopsis of the Japanese species of Protura. Contributions from the Biological Laboratory, Kyoto University 6(1): 1–43. [VIII Pls]
  • Imadaté G (1964) Taxonomic arrangement of Japanese Protura (II). Bulletin of the National Museum of Nature and Science, Tokyo 7(3): 263–293.
  • Imadaté G (1965) Proturans – fauna of Southeast Asia. Nature and Life in Southeast Asia 4: 195–302.
  • Imadaté G (1973) Contributions towards a revision of Japanese Protura. Revue d’Écologie et de Biologie du Sol 10: 603–628.
  • Imadaté G (1974) Fauna Japonica. Protura (Insecta). Keigaku Publishing, 345 pp.
  • Imadaté G (1986a)
  • Imadaté G (1986b) Change of a preoccupied generic name in the Japanese Protura. Kontyû 54: 308.
  • Imadaté G (1989) Occurrence of Huhentomon and Hesperentomon (Protura) in Japan. Bulletin of the biogeographical Society of Japan 44: 157–164.
  • Nakamura O (1990) Two new species of the genus Neocondeellum (Protura, Protentomidae) from Japan. Japanese Journal of Entomology 58: 593–605.
  • Nakamura O (2010) Taxonomic revision of the family Eosentomidae (Hexapoda: Protura) from Japan. Zootaxa 2701: 1–109.
  • Nakamura O (2014) Fujientomon primum, a rare proturan species collected in a survey of “Flora and fauna of the Imperial Palace, Tokio II”. Memories of the National Museum of Nature and Science, Tokio 50: 59–64.
  • Nosek J (1973) The European Protura, their taxonomy, ecology and distribution with keys for determination. Muséum d’Histoire Naturelle, Genève, 345 pp.
  • Nosek J (1976) A new species of Protura from Greece: Protentomon hellenicum sp. n. Revue suisse de Zoologie 83: 757–759.
  • Nosek J (1978a) Key and diagnoses of Proturan genera of the world. Annotationes zoologicae et botanicae, Bratislava 122: 1–59.
  • Nosek J (1978b) Madagascarian Protura I. Taxonomy. Bulletin du Muséum national d’Histoire naturelle, Paris (3 sér. ) 41(512): 3–28.
  • Rusek J (1974) Zur Taxonomie einiger Gattungen der Familie Acerentomidae (Insecta, Protura). Acta entomologica bohemoslovaca 71: 260–281.
  • Rusek J (1975) Zur Taxonomie und Synökologie der Gattung Proturentomon Silvestri (Protura). Věstník československé Společnosti zoologické 39: 279–292.
  • Rusek J, Shrubovych J, Szeptycki A (2012) Head porotaxy and chaetotaxy of order Acerentomata (Protura). Zootaxa 3262: 54–61.
  • Rusek J, Stumpp J (1989) Ionescuellum ulmiacum sp. n. from Central Europe (Protura, Hesperentomidae). Revue d’Écologie et de Biologie du Sol 26: 527–533.
  • Silvestri F (1907) Descrizione di un nuovo genere d’insetti apterigoti, rappresentante di un novo ordine. Bollettino del Laboratorio di Zoologia generale e agraria della R. Scuola superiore d’Agricoltura. Portici 1: 296–311.
  • Silvestri F (1909) Descrizioni preliminari di vari Artropodi. Specialmente d’America. Rendiconti della Regia Accademia dei Lincei 18: 7–10.
  • Shrubovych J (2010) Redescription of Hesperentomon tianshanicum Martynova, 1970 (Protura: Acerentomata, Hesperentomidae) and key to Hesperentomon species. Zootaxa 2720: 28–34.
  • Shrubovych J (2011) Redescription of Verrucoentomon montanum new status (=Acerella montana Martynova) (Protura: Acerentomidae, Nipponentominae). Zootaxa 2743: 63–67.
  • Shrubovych J (2014) Identification and character analysis of the Acerentomidae (Protura) of the northeastern Palearctic (Protura: Acerentomidae). Zootaxa 3755(2): 136–164. http://dx.doi.org/10.11646/zootaxa.3755.2.2
  • Shrubovych J, Bartel D, Szucsich NU, Resh MG, Pass G (2016) Morphological and genetic analysis of the Acerentomon doderoi group (Protura: Acerentomidae) with description of A. cristiani sp. nov. Plos One 11(4): e0148033. https://doi.org/10.1371/journal.pone.0148033
  • Shrubovych J, Bernard E (2012) Two new species of Verrucoentomon Rusek (Protura: Acerentomidae, Nipponentominae) and a key to species. Annals of the Entomological Society of America 105(5): 628–637. https://doi.org/10.1603/AN11175
  • Shrubovych J, Bernard E (2013) Review of Tuxenentulus and Fjellbergella species (Protura: Acerentomidae, Acerentominae). Annals of the Entomological Society of America 106(6): 673–683. http://dx.doi.org/10.1603/AN12116
  • Shrubovych J, Rusek J (2010) Sugaentulus andrzeji sp. nov. from Siberia, Russia (Protura: Acerentomidae: Acerentominae) and key to Acerentominae genera. Zootaxa 2720: 59–68.
  • Shrubovych J, Rusek J, Bernard EC (2012a) Redefinition and four new species of Yavanna Szeptycki and comparison with Nosekiella Rusek (Protura: Acerentomidae: Nipponentominae). Annals of the Entomological Society of America 105(1): 3–19. http://dx.doi.org/10.1603/AN11119
  • Shrubovych J, Rusek J, Bernard EC (2014b) Revision of Vesiculentomon, Nosekientomon n.g. (Protura: Acerentomidae, Nipponentominae), and a key to genera of Nipponentominae. Annals of the Entomological Society of America 107(1): 74–80. http://www.bioone.org/doi/full/10.1603/AN12135
  • Shrubovych J, Rusek J, Smykla J, Bernard EC (2014c) Review of Alaskaentomon (Protura: Acerentomidae, Nipponentominae). Annals of the Entomological Society of America 107(4): 728–733. http://www.bioone.org/doi/full/10.1603/AN13161
  • Shrubovych J, Rusek J, Smykla J, Bernard EC (2015) Review of North American Verrucoentomon species (Protura: Acerentomidae, Nipponentominae), with a key to species of the related genus Imadateiella Rusek. Florida Entomologist 98(1): 215–222. https://doi.org/10.1653/024.098.0137
  • Shrubovych J, Schneider C, D’Haese CA (2012b) Description of a new species of Acerentulus Berlese 1908 (Protura: Acerentomata: Acerentomidae) with its barcode sequence and a key to the confinis group. Annales de la Société Entomologique de France 48(1–2): 1–7. https://doi.org/10.1080/00379271.2012.10697746
  • Shrubovych J, Schneider C, D’Haese C (2014d) Two new species of Acerentulus Berlese, 1908 (Protura: Acerentomata: Acerentomidae) with its barcode sequence and a key to the cunhai group. Annales de la Société Entomologique de France 50(2): 129–140. https://doi.org/10.1080/00379271.2014.934036
  • Shrubovych J, Schneider C, D’Haese C (2014e) Revision of genus Andinentulus (Protura Acerentomidae: Berberentulinae), with a key to South and Central American Acerentomidae species. Annals of the Entomological Society of America 107(3): 567–574. https://doi.org/10.1603/AN13151
  • Shrubovych J, Smykla J (2012) Review of Paracerella Imadaté (Protura: Acerentomidae, Nipponentominae) with identification key and description of a new species. Zootaxa 3509: 69–76. https://doi.org/10.11646/zootaxa.3509.1.4
  • Shrubovych J, Starý J, D’Haese C (2017) Molecular phylogeny of Acerentomidae (Protura), with description of Acerentuloides bernardi sp. nov. from North America. Florida Entomologist 100(2): 433–443. https://doi.org/10.1653/024.100.0205
  • Shrubovych J, Szeptycki A (2006) Noldo kaprusii n. sp., a new species from Crimea (Protura: Nipponentomidae). Genus 17(2): 151–158.
  • Szeptycki A (1988) New genera and species of Protura from the Altai Mts. Acta Zoologica Cracoviensia 31B(7): 297–362.
  • Szeptycki A (1993) Gracilentulus species of “gracilis” group (Protura, Berberentomidae). Acta Zoologica Cracoviensia 35: 381–411.
  • Szeptycki A (1995a) The Porotaxy in Protura – a preliminary report. Polskie Pismo Entomologiczne 64(1-4): 63–67.
  • Szeptycki A (1995b)
  • Szeptycki A (2007) Catalogue of the World Protura. Acta Zoologica Cracoviensia 50B(1): 1–210.
  • Szeptycki A, Broza M (2004) Tuxenidia hermonensis (Protura: Acerentomidae), a new species from Israel, and notes on the systematics of Tuxenidia. Israel Journal of Entomology 34: 19–27.
  • Szeptycki A, Weiner W (1997) Najtentulus silvestris gen. n., sp. n. (Protura: Acerentomidae) from the Western Europe. Annales de la Société entomologique de France 33: 19–27.
  • Tuxen SL (1964) The Protura. A revision of the species of the world. With keys for determination. Hermann, Paris, 360 pp.
  • Tuxen SL (1976) The Protura (Insecta) of Brazil, especially Amazonas. Amazoniana 5: 417–463.
  • Tuxen SL (1977a) Protura (Insecta) from Angola and Nigeria with a key to Subsaharan Protura. Publicações culturais da companhia de diamantes de Angola 89: 175–193.
  • Tuxen SL (1977b) The genus Berberentulus (Insecta, Protura) with a key and phylogenetical considerations. Revue d’Écologie et de Biologie du Sol 14: 597–611.
  • Tuxen SL (1979) Protura (Insecta) from Gabon and Nigeria. Revue d’Écologie et de Biologie du Sol 16: 569–585.
  • Tuxen SL (1980) Notes on the Silvestridia complex (Insecta, Protura) in Madagascar. Revue d’Écologie et du Biologie de Sol 17: 437–443.
  • Tuxen SL (1981) The systematic importance of “the striate band” and the abdominal legs in Acerentomidae (Insecta: Protura). With a tentative key to acerentomid genera. Entomologica Scandinavica Supplement 15: 125–140.
  • Tuxen SL (1982) The Protura (Insecta) of Madeira. Bocagiana 65: 1–20.
  • Tuxen SL (1984) Brasilidia and a new genus and species of Protura (Insecta) from Argentina. Together with an improved generic key to Acerentomidae. Revue d’Écologue et de Biologie du Sol 21(2): 283–295.
  • Tuxen SL (1985) Protura (Insecta) – Fauna of New Zealand, No 9. Department of Scientific and Industrial Research, Wellington, 50 pp.
  • Tuxen SL, Yin WY (1982) A revised subfamily classification of the genera of Protentomidae (Insecta: Protura) with description of a new genus and new species. Steenstrupia 8(9): 229–249.
  • Yin WY (1983) Grouping the known genera of Protura under eight families with keys for determination. Contributions from Shanghai Institute of Entomology 1982/1983: 151–163.
  • Yin WY (1999) Arthropoda. Protura. Fauna Sinica. Science Press, Beijing, 510 pp. [8 pls]
  • Yin WY, Dallai R (1985) First record of the Somali Protura. Contributions from Shanghai Institute of Entomology 5: 171–181.
  • Yin WY, Xie R, Zhang J (1994) Phylogeny and biogeography of Condeelum [sic!] group (Protura: Protentomidae). Entomologia sinica 1: 195–204.
  • Wu DH, Yin WY (2008) The Protura from Changbai Mountain, northeastern China: I. Genera Chosonentulus Imadaté & Szeptycki and Filientomon Rusek. Annales de la Société Entomologique de France 44(3): 379–384. https://doi.org/10.1080/00379271.2008.10697574
  • Wu DH, Yin WY (2011) New genus Liaoxientulus (Protura, Acerentomidae) from Northeast China. Acta Zootaxonomica Sinica 36(4): 854–860.
  • Xiong Y, Bu Y, Yin WY (2008) A new species of Anisentomon from Hainan, Southern China, (Protura: Eosentomidae). Zootaxa 1727: 39–43.
  • Zhang Z, Yin WY (1984) A revision of the species and genera of the subfamily Anisentominae. Entomotaxonomia 6(1): 59–76.