Research Article |
Corresponding author: Aron D. Katz ( aronkatz@illinois.edu ) Academic editor: Louis Deharveng
© 2015 Aron D. Katz, Rosanna Giordano, Felipe Soto-Adames.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Katz AD, Giordano R, Soto-Adames F (2015) Taxonomic review and phylogenetic analysis of fifteen North American Entomobrya (Collembola, Entomobryidae), including four new species. ZooKeys 525: 1-75. https://doi.org/10.3897/zookeys.525.6020
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The chaetotaxy of 15 species of eastern North American Entomobrya is redescribed in order to determine potential characters for the diagnosis of cryptic lineages and evaluate the diagnostic and phylogenetic utility of chaetotaxy. As a result, four new species (E. citrensis Katz & Soto-Adames, sp. n., E. jubata Katz & Soto-Adames, sp. n., E. neotenica Katz & Soto-Adames, sp. n. and E. unifasciata Katz & Soto-Adames, sp. n.) are described, and new diagnoses are provided for E. assuta Folsom, E. atrocincta Schött, E. decemfasciata (Packard), E. ligata Folsom, E. multifasciata (Tullberg), and E. quadrilineata (Bueker). Furthermore, previously undocumented levels of intraspecific variation in macrosetal pattern are reported, tempering the exclusive use of chaetotaxy for species delimitation. Phylogenetic relationships, estimated using both morphological and molecular data, indicate that Entomobrya is likely paraphyletic. The phylogenies also suggest that unreliable character homology, likely fostered by Entomobrya’s profusion of macrosetae, may limit the phylogenetic utility of chaetotaxy in groups characterized by an abundance of dorsal macrosetae.
Chaetotaxy, cryptic species, phylogeny, species diagnosis, Willowsia
Studies concerning species delimitation and taxonomy of Collembola have traditionally relied on comparative morphology. For some groups, however, uncertain homology, intraspecific variation, and characters of difficult observation have limited the utility of morphological characters as tools for species diagnosis and phylogenetic inference. Recent advances in DNA sequencing technology have provided scientists with additional ways to delimit groups that lack informative morphology, such as cryptic species complexes (
Taxonomy and species delimitation of the genus Entomobrya Rondani, 1861 has been especially problematic due to intraspecific morphological variation and a general lack of informative taxonomic characters (
Chaetotaxy has surely proven to be a valuable tool for springtail taxonomists, but not without complications. For some groups, especially those characterized by large numbers of setae, such as Entomobrya, the homology of macrosetae is not always clear. Intraspecific variation, apparent differences in setae arrangements, and differences of setae types make it difficult to determine homology between species (
Approximately 146 specimens, representing 15 Entomobrya species (11 previously reported, 4 new), were examined in detail throughout the course of this study. Historical collections of Entomobrya from the Illinois Natural History Survey were also examined, but were not useful for the present study. Specimens preserved in 70% EtOH are old (e.g., collected prior to 1980) and in poor condition; although color pattern is often preserved, chaetotaxy and other small, but diagnostic, characters are extremely difficult to observe with confidence. Therefore, more recent material was needed to study details of chaetotaxy and other characters. Most specimens examined were collected by the senior author between 2011 and 2012 or otherwise provided by colleagues from localities throughout the USA, east of the Mississippi River. In the Material Examined sections it is assumed that the senior author collected all material, unless otherwise noted. Specimens were usually collected from leaf litter and extracted using a Berlese funnel or hand collected from bark and vegetation with an aspirator. Table
List of all Entomobrya species reported from North America. Of the 31 species, 15 were examined for this study and 16 were not included.
Species examined and described for this study | Species not included in study | |
---|---|---|
eastern species |
western species |
|
E. assuta | E. comparata | E. arnaudi |
E. atrocincta | E. confusa | E. arula |
E. bicolor | E. gisini | E. erratica |
E. citrensis sp. n. | E. griseoolivata | E. kincaidi |
E. clitellaria | E. sinelloides | E. nigriceps |
E. decemfasciata | E. suzannae | |
E. intermedia | E. triangularis | |
E. jubata sp. n. | E. troglodytes | |
E. ligata | E. troglophila | |
E. multifasciata | E. washingtonia | |
E. neotenica sp. n. | E. zona | |
E. nivalis | ||
E. quadrilineata | ||
E. unifasciata sp. n. | ||
E. unostrigata |
Individuals sampled were sorted under a dissecting microscope to morphospecies according to color pattern and photographed to record dorsal thoracic and abdominal color patterns prior to slide mounting. All specimens were cleared with Nesbitt’s solution and mounted on Hoyer’s medium (
All type specimens of E. assuta, E. decemfasciata, E. ligata, and E. quadrilineata deposited at the Illinois Natural History Survey, Champaign, IL, were examined. Types were either unavailable or their repository was unknown for most other species included in this study: E. atrocincta, unknown; E. bicolor Guthrie, unknown; E. clitellaria Guthrie, type stored at the Department of Animal Biology at the University of Minnesota (unavailable); E. intermedia Brook, unknown; E. multifasciata, unknown; E. nivalis (Linnaeus), unknown; and E. unostrigata Stach, type stored at the Institute of Systematics and Evolution of Animals of the Polish Academy of Sciences, Krakow, Poland (not examined). Additional types for E. decemfasciata are stored at the Museum of Comparative Zoology, Harvard (unavailable), and E. ligata and E. assuta at the American Museum of Natural History, New York (unavailable).
Four new species are described and named based on morphological and molecular differentiation: Entomobrya unifasciata sp. n., Entomobrya citrensis sp. n., Entomobrya neotenica sp. n. and Entomobrya jubata sp. n., originally identified as Entomobrya ligatacolor form B, Entomobrya assuta color form D, Entomobrya sp. n. 1 and Entomobrya sp. n. 2 in
Color pattern: Entomobrya is characterized by distinct, but often complex and variable, color patterns. Given this diversity of color forms, color pattern was given a secondary diagnostic role partly due to confusion in the taxonomic literature caused by presumed occurrences of intra- and inter-population color pattern variation (
Apical bulb of 4th antennal segment: The apical bulb of the 4th antennal segment is present in all species of North American Entomobrya (except E. sinelloides Christiansen, 1958b) and has a number of different forms (e.g., single lobe, bi-lobed, tri-lobed).
Apical sense organ of 3rd antennal segment: This setal complex consists of two sense pegs, “guard setae”, and a number of differentiated setae (
Differentiated setae on ventral side of 1st antennal segment: Several small, spine-like setae occur on the ventral side of the 1st antennal segment. However, no useful variation was observed for the diagnosis of species treated here.
Eye patch setae: The number of setae in the eye patch (Fig.
Prelabral and labral chaetotaxy: The number of setae in the prelabral and three labral rows is 4,5,5,4, typical of Entomobryidae. However, the prelabral setae (row basal to labrum), which are usually ciliate, may appear to be smooth under low magnification for some species of Entomobrya.
Labral papillae: The morphology of the labral papillae (Fig.
A Entomobrya atrocincta. SEM photograph of mouth cone, four labral papillae with multiple projections (1) (arrow points to 3rd papilla from left to right) and labial appendage (2) B–D drawings of labral papillae of Entomobrya and Willowsia species: Entomobrya with multiple projections per papilla (column B); Entomobrya with a single projection per papillae (column C); labral papillae of all Willowsia species occurring in the Eastern United Sates (column D). Note Willowsia n. sp. 1 can be differentiated by the presence of multiple projections per papilla. E. jubata sp. n. and E. ligata are not included in figure but are similar to E. clitellaria and E. unifasciata sp. n. respectively. Scale bars = 20 µm.
Labial appendage:
Labial chaetotaxy: Labial palp proximal setae, labial triangle setae, and post-labial setae have been shown to be taxonomically informative for other genera (
Dorsal chaetotaxy: The introduction of “stable” character systems for dorsal macrosetae (
Differences of macrosetae abundance within thoracic chaetotaxy zones A, L, M, Pm, and Pl for Th. 2 (top) and Th. 3 (bottom): A E. assuta with the lowest number of macrosetae B E. atrocincta with a moderate number of macrosetae C E. unostrigata with a moderate number of macrosetae D E. decemfasciata with the most macrosetae. Marked differences in zone Pm for both segments clearly differentiate between some groups of Entomobrya. Scale bars = 100 µm.
Trochanteral organ: Differences in number and arrangement of small, spine-like setae on the trochanter, termed the trochanteral organ, have also been used to support the identification of some species (
Male genital plate: Differences in chaetotaxy of the male genital plate can accurately delineate many North American Entomobrya species (
Mucro and tarsal claw: Ratios of relative positions of mucronal and ungual teeth do not usually deform by the mounting process, but they depend heavily on the angle or position of the slide mount in order to properly standardize relative measurements between individuals. Additionally, these characters present few discernable differences between Entomobrya species and have been noted to be of little taxonomic value for European Entomobrya (
Anatomical measurement ratios: Some authors have used relative anatomical length or distance ratios for Entomobrya species separation (
Descriptions of adult dorsal macrosetae provided in this study follow the dorsal trunk chaetotaxy nomenclature established by
Entomobrya atrocincta. SEM photographs of selected morphological characters: A close-up view of 3rd abdominal segment, macroseta (socket of a3 and m3 are labeled), type 5 microseta (1), mesoseta (2), bothriotricha (3), the dotted line represents the medial division of Abd. 3 B comparison between a pseudopore (1) and macroseta socket (2). Scale bars = 20 µm.
In order to investigate the effects chaetotaxy and other morphological characters have on phylogenetic relationships, Bayesian and maximum likelihood phylogenetic analyses were conducted using MrBayes v. 3.2.1 (
The morphological analysis of 22 taxa, including 14 species of Entomobrya and 8 additional species, was based on 179 morphological characters. Pseudosinella violenta (Folsom) was selected as the outgroup. Character state assignments (Suppl. material
The combined analysis incorporating complete COI sequences (1539 bp) for 89 exemplars (See
Dorsal setae were identified by their relative positions to bothriotricha, sensilla, pseudopores, and to neighboring setae, following descriptions provided by
This genus characterized by having 8+8 eyes within black or dark blue patches of pigment, a bidentate mucro with a smooth basal spine, basic chaetotaxy formed by type 5 microsetae and the absence of antennal sub-segmentation, scales, dental spines, and differentiated “smooth” setae on the inner surface of the hind tibiotarsus.
In addition, all species treated here have an apical antennal bulb; main sensilla on 3rd antennal segment sense organ thin, smooth, blunt and peg-like; differentiated smooth setae on ventral side of 1st antennal segment of two types, short and spine-like and long and seta-like; labral setae 5,5,4 and smooth; outer maxillary lobe of maxilla with subapical and apical setae smooth and subequal, and sublobal plate with three smooth seta-like appendages; lateral appendage of labial papilla E slightly curved, relatively thick, blunt; all post labial setae type 5; unguis with one outer, two lateral and four inner teeth, and a lanceolate unguiculus; and mucronal spine smooth; and most have all posterior setae of labial triangle ciliate, as M1, r, E, L1, L2, with r significantly smaller than other setae and A1-A5 smooth.
More general morphological descriptions of this genus are provided in
Informative diagnostic adult chaetotaxy characters of all Entomobrya species treated here are listed in Table
Informative diagnostic adult chaetotaxy for the separation of all Entomobrya species in this study5,6. These characters were specifically chosen for their ease of observation, stability, and lack of polymorphic states. Refer to species remarks for more specific diagnostic characters. Parentheses indicate a rarely observed state.
Head macrosetae |
Th. 2 macrosetae |
Abd. 2 macrosetae |
Abd. 3 macrosetae |
Prelabral setae |
Number of eye patch setae |
Labral papilla |
|||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Species | M3i | S’0 | S4i | Ps3 | Ps5 | m2 | m5 | a2 | a3 | m3ep | a1 | a2 | |||
E. assuta | 0 | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 0 | 1 | 0 | 5 | 0 |
E. atrocincta | 0(1) | 0 | 1 | 0 | 1 | 1 | 0 | 1 | 1(0) | 0(1) | 1 | 1 | 1 | 5 | 0 |
E. bicolor | 1 | 0 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 5 | 1 |
E. citrensis sp. n. | 0 | 0 | 1 | 1 | 1 | 0 | 0 | 0 | 1 | 0 | 0 | 1 | 0 | 5 | 0 |
E. clitellaria | 0 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 5 | 1 |
E.
decemfasciata
|
1 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 5 | 1 |
E. intermedia | 0 | 0 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 0 | 1 | 5 | 0 |
E. jubata sp. n. | 0 | 1 | 1 | 0 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 5 | 1 |
E.
ligata
|
0 | 0 | 1 | 0 | 1 | 1 | 0 | 1 | 0 | 1 | 0 | 0 | 0 | 3 | 1 |
E. multifasciata | 0 | 0 | 0 | 0 | 1 | 1 | 0 | 1 | 1 | 0 | 1 | 1 | 1 | 5 | 0 |
E. neotenica sp. n. | 0 | 0 | 0(1) | 0 | 1 | 1 | 0 | 1 | 0 | 0 | 0 | 0 | 0 | 3 | 1 |
E. nivalis | 0 | 0 | 1 | P | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 5(6) | 0 |
E.
quadrilineata
|
1 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 1 | 5(6) | 1 |
E. unifasciata sp. n. |
0 | 0 | 1 | 0 | 1 | 1 | 0 | 1 | 0(1) | 1 | 0 | 0 | 0 | 3 | 1 |
E. unostrigata | 0 | 0 | 1 | 0 | 1 | 0 | 1 | 1 | 1 | 1 | 1 | 0 | 1 | 5 | 0 |
Body shape and color pattern. Body dorso-ventrally flattened. Dorsal color pattern highly variable, and in many cases, without clear discrete forms (Fig.
Head. Apical bulb of 4th antennal segment usually bilobed, sometimes simple or, rarely, trilobed. Long differentiated smooth setae on ventral side of 1st antennal segment ≈3x short setae. Prelabral setae finely ciliated, seemingly smooth at low magnification under light microscopy. Distal margin of labral papillae with 2-3 small spine-like projections (Fig.
Thorax. Thoracic chaetotaxy extremely reduced but stable, without macrosetae variation in specimens studied. A row of microsetae present along entire posterior margin of Th. 2 and Th. 3 (not displayed in figures). Th. 2, with a5 and 5 posterior macrosetae (Fig.
Legs. Trochanteral organ with triangular setal pattern and up to 23 setae. Unguis with 4 inner teeth; basal teeth located approximately middle of inner claw length.
Abdomen. Abdominal chaetotaxy reduced but stable, no macrosetae variation observed. Abd. 1 with 1 macroseta only (Fig.
Entomobrya assuta is the only species with the color pattern as described above in combination with the absence of all the following macrosetae: head Ps3, Th. 2 m2 and m3, Abd. 2 a2, a3 and m3ep, and Abd. 3 a1 (see Table
Subsequent comparative morphological observations between the two forms show that head macroseta Ps3 and Abd. 2 macroseta a3 are both absent in E. assuta, but present in E. citrensis sp. n.; additionally, E. citrensis sp. n. has a complete, dark transverse band located medially across Abd. 4, whereas this band is absent in E. assuta. Labral morphology also separates these species, E. assuta has relatively uniform labral papillae, each with two to three seta or spine-like projection, whereas E. citrensis sp. n. has up to five minute bumps or serrations on the two internal papillae and only two larger spine-like projections on the two external papillae (Fig.
Entomobrya assuta appears to be an intrusion of a southern subtropical or tropical Entomobrya lineage into the Nearctic region.
Endemic to North America (Suppl. material
USA: Cotypes (J. W. Folsom), 2 on slide, Vermont, Clarendon, under bark Mar-April 1898 (O. W. Barrett),
Body shape and color pattern. Sexually dimorphic in color pattern and body shape. Males and females with variable but characteristically different color patterns (Fig.
Head. Apical bulb of 4th antennal segment located in deep pit, usually simple, sometimes with up to four distinct lobes. Long differentiated smooth setae on ventral side of 1st antennal segment ≈2.5x short setae. Prelabral setae ciliate. Ornamentation of distal margin of labral papillae with 3-4 small seta or spine-like projections (Fig.
Thorax. Chaetotaxy of Th. 2 stable, without variation in number of macrosetae. A row of microsetae occurs along entire posterior margin of Th. 2 (not displayed in figure); a5, m1, m2, m4, m4p, and all posterior macrosetae (series Pi, Pa, Pm, and Pp) present (Fig.
Legs. Trochanteral organ with triangular setal pattern and up to 30 setae. Unguis with 4 internal teeth; basal teeth located approximately middle of inner claw length.
Abdomen. Abdominal chaetotaxy variable. Abd. 1, with 4-8 macroseta (Fig.
Entomobrya atrocincta can be distinguished by the male or female color patterns as described above combined with the presence of macrosetae head S4i and Abd. 3 a1 and a2 and the absence of macrosetae head ps3 and Th. 2 m5 (see Table
Diagnostic characters to separate species within the nivalis complex: E. atrocincta, E. multifasciata, E. intermedia, and E. nivalis. Diagnostic characters of E. clitellaria are also included in relation to E. atrocincta due to similarity in color pattern.
Species | Head macroseta S4i |
Th. 2 macroseta m5 |
Abd. 2 macroseta m3ep |
Abd. 3 macroseta a1 |
Abd. 3 macroseta a2 |
Labral papillae |
---|---|---|---|---|---|---|
E. atrocincta | 1 | 0 | 0(1) |
1 | 1 | 0 |
E. multifasciata | 0 | 0 | 0 | 1 | 1 | 0 |
E. intermedia | 0 | 1 | 0 | 1 | 0 | 0 |
E. nivalis | 1 | 1 | 1 | 1 | 0 | 0 |
E. clitellaria | 1 | 1 | 1 | 0 | 1 | 1 |
The male form always has a unique orange color, but the distribution of purple pattern is variable.
Sexual dimorphism in this species has caused serious taxonomic confusion due to the similarity of female pattern to E. multifasciata and E. nivalis.
Comparison between descriptions of E. atrocincta (and E. nigrocincta) provided by this study with those provided by
Species description | Sexual dimorphism | H1 | H2 | H3 | H4 | H5 | T1 | T2 | A1 | A2 | A3 | A4 | A5 | A6–A10 |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
E.
atrocincta
|
Yes | 3 | 2(1) | 0 | 3 | 2 | 2 | 3 | 2(1) | 2(3) | 1 | 2 | 1 | 8-11 |
E.
nigrocincta
|
Yes | 3 | 1 | 0 | 2 | 2 | 2 | 3 | 1 | 2 | 1 | 1 | 1 | 9(8?) |
E.
atrocincta
|
No | 2 | 1 | 0 | 3 | 2(3) | 2 | 3 | 2 | 3 | 1 | 2 | 1 | 13 |
E.
atrocincta
|
No | ? | ? | ? | ? | ? | ? | ? | 2 | 2 | 1 | 2 | 1 | ? |
The original description of E. atrocincta by Schӧtt (1896) was based on the male form collected from California.
North America, Hawaii and possibly Europe. Records of E. multifasciata in North America and Hawaii (
USA: 1♂ in vial, Alabama, Clay Co., Talladega National Forest, on CR6000-1 off of Hwy148 (33.19723,-86.06325), in moss on forest floor, 2.i.2012 (A. Katz & M. DuBray), AK12-5; 6♂ & 2♀ in vial, Illinois, Champaign Co., Champaign, Kaufman Lake Park (40.11514,-88.29000), in bird nest, 8.v.2011, AK11-26; 2♂ on slides, 4♂ & 6♀ in vial, Illinois, Champaign Co., Champaign, Kaufman Lake Park (40.11514,-88.29000), squirrel nest, 8.v.2011, AK11-27; 7♂ & 7♀ on slides, 50+♂ & 50+♀ in vial, Illinois, Champaign Co., Urbana, Natural Resource Building (40.10071,-88.22812), in leaf litter under bush by parking lot, 22.iv.2011, AK11-17; 1♂ on slides, Illinois, Champaign Co., Urbana, Meadowbrook Park (40.08063,-88.20828), in leaf litter, 14.iv.2012, AK12-24; 3♀ in vial, Illinois, Champaign Co., Urbana, South side of Natural Resource Building (40.10110,-88.22963), in sweet gum seed pods and leaf litter, 23.iv.2011 (A. Katz & M. DuBray), AK11-15; 3♀ on slides, 20♂ & 10♀ in vial, Illinois, Champaign Co., Urbana, Natural Resource Building (40.10047,-88.22840), in leaf litter under bush along Pennsylvania Ave, 5.v.2011, AK11-25; 1♂ & 1♀ on slides, 50+♂ & 50+♀ in vial, Tennessee, Knox Co., University of Tennessee, Ag. Campus, Morgan Hall (36.01023,-83.93829), on moist fallen bark, April 2010 (E. C. Bernard); 1♂ & 1♀ in vial, Tennessee, Knox Co., Farragut, 12108 Ridgeland Drive (36.01023,-83.93829), in old bald-faced hornet nest, 2.iii.2008 (E. C. Bernard).
Body shape and color pattern. Body elongate and cylindrical. Only one reported color form in adults (Fig.
Head. Apical bulb of 4th antennal segment usually bilobed, rarely simple. Long differentiated smooth setae on ventral side of 1st antennal segment ≈ 3–4× short seta. Prelabral setae ciliate. Ornamentation of the distal margin of the labral papillae with a single seta or spine-like projection (Fig.
Thorax. Thoracic chaetotaxy abundantly developed, highly variable with many supplemental macrosetae. Th. 2 macrosetae p6e and p6ep absent and macrosetae m4i2, m4i3 polymorphic (Fig.
Legs. Trochanteral organ with rectangular setal pattern and up to 37 setae. Unguis with 4 internal teeth; basal teeth enlarged and located approximately middle of inner claw length.
Abdomen. Abdominal chaetotaxy highly developed. Row of microsetae along entire posterior margin present in all segments (not displayed in figure). Abd. 1 with 12 macrosetae (Fig.
Macrosetae variation and asymmetrical polymorphism of Abd. 4 in the E. bicolor complex: A E. bicolor B E. decemfasciata C E. quadrilineata. Only medial macrosetae (those which occur between bothriotricha T2 and T4) are included in diagram. The dotted line represents the medial division of Abd. 4. Scale bars = 100 µm.
Entomobrya bicolor adults can be easily distinguished by the unique color pattern described above combined with the absence of head macroseta Ps5 (see Table
Important diagnostic characters for the separation of species within the bicolor complex: E. bicolor, E. decemfasciata, and E. quadrilineata. Character states: absent (0), present (1).
Species | Head macrosetae Ps5 | Parallel, longitudinal bands on thorax |
---|---|---|
E. bicolor | 0 | 0 |
E. decemfasciata | 1 | 0 |
E. quadrilineata | 1 | 1 |
Endemic to North America (Suppl. material
USA: 9 on slides, 6 in vial, Illinois, Henderson Co., Big River State Forest (41.03435,-90.91620), vacuum sand prairie, 8.vi.2011 (C. H. Dietrich).
This species is named after the locality it was collected in: Citrus County, Florida. Citrensis is Latin for “from the place of citrus”.
Holotype, ♂, USA: Florida, Citrus County, Chassahowitzka National Wildlife Refuge (28.75997,-82.57583), beating vegetation, 12.viii.2011 (A. Katz & J. Cech), AK11-134.
Paratypes, USA: 1 on slide, Florida, Citrus Co., Chassahowitzka National Wildlife Refuge (28.75997,-82.57583), under bark, 12.viii.2011 (A. Katz & J. Cech), AK11-136; 1 on slide, Florida, Citrus Co., Chassahowitzka National Wildlife Refuge (28.75997,-82.57583), beating vegetation and in leaf litter, 5.i.2014 (A. Katz & M. DuBray), AK14-1.
Body shape and color pattern. Body dorso-ventrally flattened. Length up to 1.4mm. Color pattern monomorphic (Fig.
Head. Apical bulb of 4th antennal simple. Long differentiated smooth setae on ventral side of 1st antennal segment ≈2.5× short setae. Prelabral setae with very fine ciliations that look smooth at low magnification under light microscopy. Ornamentation of the distal margin of the labral papillae with 3-4 spine-like projections on the inner papillae and 2 spine-like projections on the external papillae. Lateral appendage of labial papilla E slightly curved, relatively thin, reaching just below tip of papilla. Dorsal head chaetotaxy slightly reduced (Fig.
Thorax. Thoracic chaetotaxy reduced and fixed, no macrosetae variation observed. Row of microsetae along entire posterior margin of Th. 2 and Th. 3 (not displayed in figures). Th. 2, with a5 and posterior macrosetae p4, p5, p6, p6e, and p6ep (Fig.
Legs. Trochanteral organ with triangular setal pattern and up to 14 setae. Unguis with 4 internal teeth; basal teeth located approximately middle of inner claw length (Fig.
Abdomen. Abdominal chaetotaxy reduced and stable; no macrosetae variation observed. Abd. 1 with 1 macroseta only (Fig.
Entomobrya citrensis sp. n. can be distinguished by its color pattern in combination with the absence of Th. 2 macrosetae m2 and m5, Abd. 2 a2 and m3ep, and the presence of Abd. 2 a3 (see Table
This species is closely related to E. assuta; both have highly compressed, or dorso-ventrally flattened bodies, reduced chaetotaxy, and similar color patterns. Head macroseta Ps3 and Abd. 2 macroseta a3 are both present in E. citrensis sp. n., but are absent in E. assuta. These species can also be separated by color pattern and morphology of the labral papillae (Fig.
See remarks for E. assuta for additional diagnosis information. Only a few specimens of E. citrensis sp. n. were observed from one locality. Additional sampling may reveal more variation in color pattern or chaetotaxy.
Endemic to North America. Reported from a single locality: Chassahowitzka National Wildlife Refuge in Citrus County, Florida (Suppl. material
Body shape and color pattern. Body dorso-ventrally flattened. Dimorphic color pattern, unrelated to sex (Fig.
Head. Apical bulb of 4th antennal segment usually simple, sometimes bilobed. Long differentiated smooth setae on ventral side of 1st antennal segment ≈3× short setae. Prelabral setae ciliate. Ornamentation of the distal margin of the labral papillae with a single seta or spine-like projection (Fig.
Thorax. Thoracic chaetotaxywell-developed, with some slight variation. Th. 2 macrosetae m4i3 absent, m1i usually present (Fig.
Legs. Trochanteral organ with triangular setal pattern and up to 26 setae. Unguis with 4 inner teeth; basal teeth located approximately middle of inner claw length.
Abdomen. Abdominal chaetotaxy highly developed. Abd. 1 with 8-13 macrosetae (Fig.
Entomobrya clitellaria can be distinguished by the combination of color pattern, absence of macroseta head S’0 and Abd. 3 a1 and presence of head Ps5, Th. 2 m5, Abd. 2 m3ep, and Abd. 3 a2 (see Table
This species is closely related to E. jubata sp. n., but can be easily separated by color pattern, chaetotaxy, and morphology of the labral papillae. The absence of head macrosetae S’0 and the presence of head macrosetae Ps5 separate E. clitellaria from E. jubata sp. n. Labral papillae morphology also differs between these species: E. jubata sp. n. has two or three seta or spine-like projection on each papilla, while E. clitellaria only has one seta or spine-like projection per papilla (Fig.
Endemic to North America (Suppl. material
USA: 1 on slide, Florida, Taylor Co., Econfina State Park (30.0656,-83.91066), under bark, 9.viii.2011, AK11-116; 1 in vial, Illinois, Champaign Co., Urbana, Brownfield Woods (40.14462,-88.16543), on bushes and low-lying shrubs, 7.vii.2011, AK11-60; 1 on slide, Illinois, Champaign Co., Urbana, Brownfield Woods (40.14391,-88.16468), under bark, 10.ix.2009 (F. Soto-Adames); 1 in vial, Illinois, Coles Co., Fox Ridge State Park (39.40248,-88.14893), under bark, 15.vii.2011 (A. Katz & F. Soto-Adames), AK11-81; 3 on slides, 20 in vials, Illinois, Jasper Co., Sam Parr State Fish and Wildlife Area (39.03275,-88.12474), under bark, 15.vii.2011 (A. Katz & F. Soto-Adames), AK11-73, AK11-74 & AK11-75; 1 in vial, Illinois, Jasper Co., Sam Parr State Fish and Wildlife Area (39.03275,-88.12474), in leaf litter, 15.vii.2011 (A. Katz & F. Soto-Adames), AK11-77; 1 on slide, 1 in vial, Illinois, Jo Davies Co., Princess Mine 1 (42.30565,-90.39740), under bark, 26.viii.2011, AK11-142; 1 in vial, Illinois, Jo Davies Co., S Blanding Rd, Stevenson Property (42.29895,-90.36967), under bark, 27.viii.2011, AK11-148; 1 on slide, Illinois, Kankakee Co., Kankakee River State Park (41.19482,-87.96875), from bird nest, 10.iv.2011, AK11-6; 4 on slides, Illinois, Monroe Co., Bat Sump Cave, Berlese of bark, 1-3.xi.2009 (S. Taylor & F. Soto-Adames), sjt09-130; 4 on slides, 50+ in vial, Illinois, Piatt Co., Lodge County Forest Preserve Park (40.06709,-88.56596), dead logs, cavity in tree, and under bark, 23.vii.2011, AK11-100; 2 on slides, 10 in vial, Illinois, Pope Co., Bell Smith Springs (37.51927,-88.65738), leaf litter, 24.ix.2011, AK11-166; 2 on slides, Illinois, Vermilion Co., Kickapoo State Park (40.16576,-87.74746), on rotten log, 30.xi.1989 (F. Soto-Adames); 1 in vial, Illinois, Vermilion Co., Kennekuk Cover County Park, Windfall Prairie Nature Preserve (40.20995,-87.74181), aspirated from bushes, 16.vi.2011 (A. Katz & F. Soto-Adames), AK11-59; 1 in vial, Michigan, Ingham Co., Michigan State University, Baker Wdlt. (42.66527,-84.36264) under bark of standing dead pine, 24.vii.2008 (E. C. Bernard), BW-11; 1 on slide, 3in vial, Michigan, St. Clair Co., Algonac State Park (42.65447,-82.52430), under bark of recently fallen maple, 25.vii.2008 (E. C. Bernard), ASP-15; 1 on slide, West Virginia, Monongalia Co., Tyrone (39.62746,-79.86567), under collected on the lower branches of eastern hemlock, 19.vii.2005 (R. M. Turcotte), ID#44-GE-21-5-4-A.
Body shape and color pattern. Body very elongate and cylindrical with mesothorax forming a slight hump behind head. Color pattern remarkably variable with continuous variation and many intermediate forms (Fig.
Head. Apical bulb of 4th antennal segment usually bilobed or simple, but with up to 6 distinct lobes. Long differentiated smooth setae on ventral side of 1st antennal segment ≈3× short setae. Ornamentation of the distal margin of the labral papillae with single seta or spine-like projection (Fig.
Thorax. Thoracic chaetotaxy developed, highly variable, with many supplemental macrosetae. Th. 2 macrosetae p6, p6e and p6ep absent. Macrosetae in Zone A so abundant that usually merge with medial macrosetae, forming a single, large patch of setae (Figs
Legs. Trochanteral organ with rectangular setal pattern and up to 86 setae. Unguis with 4 internal teeth; basal teeth located approximately middle of inner claw length.
Abdomen. Abdominal chaetotaxy extensively developed. Row of microsetae along entire posterior margin present in all segments (not displayed in figure). Abd. 1 with 16-30 macrosetae (Fig.
Entomobrya decemfasciata can be distinguished by the absence of parallel, longitudinal bands on the thorax, the presence of 2-4 irregular, angled bands on lateral margins of abdomen, and the presence of head macroseta Ps5 (see Table
The considerable variation in chaetotaxy and color pattern and relatively high molecular divergences between E. decemfasciata color forms suggest the presence of a cryptic species complex (
This species has a long history of taxonomic issues (
Endemic to North America (Suppl. material
USA: “Type material”, 1 on slide, Knoxville, Tennessee (Dr. Curtis),
Body shape and color pattern. Body oval and cylindrical. Color pattern monomorphic (Fig.
Head. Apical bulb of 4th antennal segment simple. Long differentiated smooth setae on ventral side of 1st antennal segment ≈5× short setae. Prelabral setae ciliate. Ornamentation of the distal margin of the labral papillae with 2-4 small spine-like projections (Fig.
Thorax: Thoracic chaetotaxy well-developed and relatively stable. Th. 2 macrosetae a5, m1, m2, m2i, m4, m4p, m4i, and m5 present (Fig.
Legs. Trochanteral organ with triangular setal pattern and up to 31 setae. Unguis with 4 internal teeth; basal teeth located approximately middle of inner claw length.
Abdomen. Abdominal chaetotaxy stable. Abd. 1 with 7 macrosetae (Fig.
Entomobrya intermedia can be easily identified by the presence of two longitudinal stripes, a W-shaped mark on Abd. 4 combined with the presence of Th. 2 macrosetae m5 and Abd. 3 a1, and the absence of head macrosetae S4i, Abd. 2 m3ep, and Abd. 3 a2 (see Table
North America and Europe. The actual distribution of E. intermedia in North America is unclear, as before
USA: 2 on slides, Pennsylvania, Chester Co., Wayne, sweep of Forsythia sp., 23.v.2011, AK11-32; 8 on slides, 12 in vial, Pennsylvania, Chester Co., Wayne, sweep of Forsythia sp., 29.vi.2012, AK12-50.
The word jubatus is Latin for maned, or crested, and refers to the abundance of dorsal macrosetae on the thoracic segments.
Holotype, ♀, USA: Alabama, Covington County, Conecuh National Forest (31.07900,-86.61203), under bark, 2.i.12 (A. Katz & M. DuBray), AK12-9 & AK12-6.
Paratypes, USA: 7 on slides, 20 in vials, Alabama, Covington Co., Conecuh National Forest (31.07900,-86.61203), under bark, 2.i.12 (A. Katz & M. DuBray), AK12-9 & AK12-6.
Body shape and color pattern. Body cylindrical, slightly dorso-ventrally flattened. Length up to 2 mm. Color pattern monomorphic (Fig.
Head. Apical bulb of 4th antennal segment usually simple, rarely bilobed. Long differentiated smooth seta on ventral side of 1st antennal segment 3× as long as short setae. Prelabral setae ciliate. Distal margin of the labral papillae with 2-3 seta or spine-like projections. Labial papilla E with lateral appendage almost straight, reaching tip of papilla. Dorsal head chaetotaxy as in Figure
Thorax. Thoracic chaetotaxy well-developed (Fig.
Legs. Trochanteral organ with triangular setal pattern and up to 25 setae. Unguis with 4 inner teeth; basal teeth located approximately middle of inner claw length (Fig.
Abdomen. Abdominal chaetotaxy abundantly developed. Abd. 1 with 12 macrosetae (Fig.
Entomobrya jubata sp. n. can be easily distinguished by the unique color pattern described above combined with the absence of head macroseta Ps5, the presence of head macroseta S’0 and Th. 2 macrosetae m2 and m5 (see Table
Endemic to North America. E. jubata sp. n. was collected from a single locality in Covington County, Alabama (Suppl. material
Body shape and color pattern. Body oval and cylindrical. Color pattern stable, monomorphic (Fig.
Head. Apical bulb of 4th antennal segment usually bilobed, sometimes multilobed. Long differentiated smooth setae on ventral side of 1st antennal segment ≈3× short setae. Prelabral setae finely ciliated, seemingly smooth at low magnification under light microscopy. Ornamentation of the distal margin of the labral papillae with single seta or spine-like projections. Lateral appendage of labial papilla E slightly curved, relatively thick and short, extending only ¾ papilla length. Dorsal head macrosetae (Fig.
Thorax. Th. 2 macrosetae a5, m1, m2, m2i, m4, m4p, and m4i present (Fig.
Legs. Trochanteral organ with triangular setal pattern and up to 17 setae. Unguis with 4 internal teeth; basal teeth located approximately middle of inner claw length.
Abdomen. Abdominal chaetotaxy reduced; no macrosetae variation observed. Abd. 1 with 4 macroseta: a5, m2, m3, and m4 (Fig.
This species can be identified by the presence of four transverse bands, head mesoseta An’0 present, four macrosetae on Abd. 1, and only three eye patch setae (see Table
Diagnostic characters to separate species within the ligata complex: E. ligata, E. unifasciata sp. n., and E. neotenica sp. n. Character states: absent (0), present (1).
Species | Head mesoseta An’0 | Abd. 3 macroseta m3ep | 1 dark transverse band on posterior margin of Th. 2 | 2 dark triangular patches on Abd. 3 |
---|---|---|---|---|
E. ligata | 1 | 1 | 1 | 0 |
E. unifasciata sp. n. | 1 | 1 | 0 | 0 |
E. neotenica sp. n. | 0 | 0 | 0(1) |
1 |
E. ligata was described by
Endemic to North America. The species has been reported as having a wide distribution, occurring east of the Mississippi River to the Atlantic coast (Suppl. material
USA: Syntypes, 1 on slide, Karner, N.Y., 7-14-23 (A. Wolf)
Body shape and color pattern. Body oval and cylindrical. One primary color form, with slight variations (Fig.
Head. Apical bulb of 4th antennal segment usually bilobed, sometimes simple. Long differentiated smooth setae on ventral side of 1st antennal segment ≈2–3× short setae. Four prelabral setae ciliate. Ornamentation of the distal margin of the labral papillae with 2-3 seta or spine-like projections (Fig.
Thorax. Th. 2 macrosetae a5, m1, m2, m4, and m4p present (Fig.
Legs. Trochanteral organ with triangular setal pattern and up to 18 setae.
Abdomen. Abd. 1 with 6-8 macrosetae (Fig.
Entomobrya multifasciata can be distinguished by the color pattern described above combined with the presence of Abd. 3 macrosetae a1 and a2 and the absence of macrosetae head S4i, Th. 2 m5, and Abd. 2 m3ep (see Table
We were unable to obtain North American samples of E. multifasciata and the description and diagnosis provided above are based on specimens from São Miguel Island, Azores, Portugal. The Nearctic distribution of this species remains unclear in light of the sexual dimorphism of E. atrocincta described in this study (see remarks for E. atrocincta).
North America (
PORTUGAL: 2 on slides, 10 in vial, Azores, São Miguel Island, (J. Marcelino), vial #119; 6 on slides, 10 in vial, Azores, São Miguel Island, (J. Marcelino), vial #86; 5 in vial, Azores, São Miguel Island, (J. Marcelino), vial #55; 4 in vial, Azores, Terceira Island, (J. Marcelino), vial #9; 4 in vial, Madeira Island, (J. Marcelino), vial #2.
This species is named for its apparent neoteny; small size and reduced chaetotaxy.
Holotype, ♂, USA: Alabama, Lawrence County, William B. Bankhead National Forest (34.3369,-87.3461), leaf litter, 9.viii.2011, AK11-112.
Paratypes, USA: 1 on slide, 1 in vial, Alabama, Clay Co., Talladega National Forest (33.19723,-86.06325), moist leaf litter, 2.i.12 (A. Katz & M. DuBray), AK12-2; 1 in vial, Alabama, Lawrence Co., William B. Bankhead National Forest (34.3369,-87.3461), leaf litter, 9.viii.2011, AK11-112; 1 on slide, Florida, Taylor Co., Econfina River State Park (30.0656,-83.9107), under bark, 9.viii.2011, AK11-116; 2 on slides, 18 in vial, Illinois, Union Co., Anna, Shawnee National Forest, Rich’s Cave, moist leaf litter under bark on fallen tree, 21.vi.2012 (F. Soto-Adames, S. Taylor & A. Katz); 1 on slide, Tennessee, Stewart Co., Land Between the Lakes National Recreation Area (36.5354,-87.9214), forest floor leaf litter, 3.v.2011, AK-43.
Body shape and color pattern. Body oval and cylindrical. Length up to 1.15 mm. One primary color form (Fig.
Head. Apical bulb of 4th antennal segment simple or bilobed. Long differentiated smooth setae on ventral side of 1st antennal segment ≈2–2.5× short setae. Four prelabral setae finely ciliate, appearing smooth under light microscopy. Ornamentation of the distal margin of the labral papillae with single seta or spine-like projections (Fig.
Thorax. Thoracic chaetotaxy reduced, with relatively few supplementary setae. Th. 2 macrosetae a5, m1, m2, m4, m4p, and m4i present (Fig.
Legs. Trochanteral organ with triangular setal pattern and up to 20 setae. Unguis with 4 inner teeth (Fig.
Abdomen. Abdominal chaetotaxy reduced; no macrosetae variation observed. Abd. 1 with 4 macrosetae; a5, m2, m3, and m4 (Fig.
Entomobrya neotenica sp. n. can be diagnosed by the presence of two lateral dark triangular shaped or irregular spots on Abd. 3, only 3 setae in eye patch, and the absence of head mesoseta An’0 and Abd. 3 macroseta m3ep (see Table
Endemic to North America (Suppl. material
Body shape and color pattern. Body cylindrical. One primary, but variable, color form (Fig.
Head. Apical bulb of 4th antennal segment usually bi- or trilobed. Long differentiated smooth setae on ventral side of 1st antennal segment ≈3× short setae. Ornamentation of the distal margin of the labral papillae with 3-4 small seta or spine-like projections per papilla (Fig.
Legs. Trochanteral organ with triangular setal pattern and up to 34 setae. Unguis with 4 internal teeth; basal teeth located approximately 60% of inner claw length. Unguiculus acuminate with small serrations on internal edge.
Thorax. Th. 2 macrosetae a5, m1, m2, m4, m4i, m4pi, and m5 present (Fig.
Abdomen. Abd. 1 with 7-10 macrosetae (Fig.
Entomobrya nivalis can be diagnosed by the presence of a U-shaped or “11” shaped pattern on Abd. 4 combined with the presence of macrosetae head S4i, Th. 2 m5, Abd. 2 m3ep, and Abd. 3 a1, and the absence of Abd. 3 a2 (see Table
It is important to note that the large genetic distances between presumably conspecific individuals (
North America and Europe. Records of E. nivalis in North America are suspect if diagnosed without considering chaetotaxy given the superficial similarities in color form expressed by E. atrocincta females (See Fig.
USA: 2 on slides, 50+ in vial, Maine, Hancock Co., Acadia National Park (44.353823,-68.224754), moss, veg. sweep (blueberry, juniper, populus), 17.viii.2011 (E. C. Bernard), #2009-37; 3 on slides, 5 in vial, Pennsylvania, Allegheny Co., Allegheny National Forest, Dewdrop campground (41.83092,-7895937), leaf litter, 8.vii.2008 (S. M. Shreve); 1 on slide, Vermont, Chittenden Co., Red Rock, Locality I (44.44493,-73.23040), leaf litter, 6.vi.2011 (J. Fisher); 2 on slides, Vermont, Chittenden Co., Farrell Park, Locality II (44.44454,-73.20178), leaf litter, 13.vi.2001 (J. Fisher); 1 on slide, Vermont, Chittenden Co., Farrell Park, Locality II (44.44454,-73.20178), leaf litter, 4.vii.2001 (J. Fisher); 2 on slides, Vermont, Chittenden Co., Farrell Park, Locality II (44.44454,-73.20178), leaf litter, 26.vii.2001 (J. Fisher); 1 on slide, Vermont, Lamoille Co., Stowe (44.48377,-72.69859), leaf litter, 24.vii.2001 (J. Fisher); 1 on slide, Vermont, Lamoille Co. (44.54858,-72.79393), DNA ID#: 12-FSVTlam-ni-1; 1 on slide, Vermont, Washington Co., Locality II, Barre (44.19968,-72.50135), leaf litter, 8.vi.2001 (J. Fisher); 2 on slides, Vermont, Washington Co., Locality II, Barre (44.19968,-72.50135), leaf litter, 24.vii.2001 (J. Fisher); 2 on slides, 6 in vial, Vermont, Rutland Co., Green Mountain National Forest, Greendale Recreation Area (43.35112,-72.82225), leaf litter, 10.vii.2008 (S. M. Shreve); 1 on slide, 6 in vial, Wisconsin, Dodge Co., Horicon Marsh National Wildlife Refuge, end of Dike Rd (43.52736,-88.64381), 12.vi.2011, AK11-47; 2 on slides, 7 in vial, Wisconsin, Sauk Co., Devil’s Lake State Park, 0.5mi down Steinke Basin Loop trail (43.4255,-89.71039), 12.vi.2011, AK11-50.
Body shape and color pattern. Body very elongate and cylindrical. Color pattern monomorphic (Fig.
Head. Apical bulb of 4th antennal segment usually bilobed. Long differentiated smooth setae on ventral side of 1st antennal segment ≈4× short setae. Four prelabral setae ciliate. Ornamentation of the distal margin of the labral papillae with single seta or spine-like projection (Fig.
Thorax. Thoracic chaetotaxy greatly developed, with high levels of variation and many supplemental macrosetae. Th. 2 zone A enlarged and sometimes merging with medial macrosetae forming a single, large patch of setae (Fig.
Legs. Trochanteral organ with rectangular setal pattern and up to 41 setae.
Abdomen. Abdominal chaetotaxy highly developed. Row of microsetae along posterior margin present in all segments (not displayed in figure). Abd. 1 with 12-16 macrosetae (Fig.
Entomobrya quadrilineata can be identified by the presence of 2 parallel longitudinal thoracic stripes combined with the presence of head macrosetae M3i and ps5 and the absence of Abd. 3 macroseta a1 (see Table
Endemic to North America (Suppl. material
USA: Neo-holotype (Christiansen 1951), 1 on slide, Fountain Bluff, Ill. 5-15-32, Coll. Ross + Mohr,
From the Latin words uno and fasciatus, which translates to “one band”. This species has only one band found along the posterior margin of the metathorax, a character that distinguishes it from E. ligata, which has two bands; one along each posterior margin of the meta- and mesothorax.
Holotype, ♂, USA: Kentucky, Laurel County, Levi Jackson State Park (37.08247,-84.04528), leaf litter collected at night, 28.v.2011, AK11-37.
Paratypes, USA: 2 on slides, 1 in vial, Georgia, Union Co., Brasstown Bald Rd., tiny water trickle near road surrounded by dryish leaves (34.86040,-83.80193), leaf litter, 26.v.2011 (E. C. Bernard) #2011-28; 1 on slide, Kentucky, Laurel Co., Levi Jackson State Park (37.08247,-84.04528), leaf litter collected at night, 28.v.2011, AK11-37; 1 on slide, 2 in vial, North Carolina, Henderson Co., Blue Ridge Parkway, Mill River Overlook (35.4482,-82.71963), under bark on logs, 4.vi.2007 (E. C. Bernard), 07031EB; 10 in vial, North Carolina, Swain Co., Great Smoky Mountains National Park, Balsom Mountain, Heintooga Ridge Rd. (35.57030,-83.16917), leaf litter along road, 29.v.2011, AK11-38; 1 on slide, 35 in vial, North Carolina, Swain Co., Great Smoky Mountains National Park, Balsom Mountain, Heintooga Ridge Rd. (35.57030,-83.16917), under bark, 29.v.2011, AK11-39;11 in vial, North Carolina, Swain Co., Great Smoky Mountains National Park, Balsom Mountain, Heintooga Ridge Rd. (35.57030,-83.16917), leaf litter by river, 29.v.2011, AK11-40; 1 on slide, 1 in vial, Tennessee, Sevier Co., Great Smoky Mountains National Park, 1 mi down greenbrier Rd. (35.72640,-83.40173), leaf litter by stream, 30.v.2011, AK11-41; 1 in vial, Tennessee, Sevier Co., Great Smoky Mountains National Park, 1 mi down greenbrier Rd. (35.72640,-83.40173), leaf litter stuck in nook of tree, 30.v.2011, AK11-42.
Body shape and color pattern. Body oval and cylindrical. Length up to 1.85 mm. Color pattern stable (Fig.
Head. Apical bulb of 4th antennal segment usually bilobed, sometimes simple. Long differentiated smooth setae on ventral side of 1st antennal segment ≈3× short setae. Four prelabral setae finely ciliate, seemingly smooth at low magnification under light microscopy. Ornamentation of the distal margin of the labral papillae with single seta or spine-like projection (Fig.
Thorax. Th. 2 macrosetae a5, m1, m2, m4, m4pi, and m4i present (Fig.
Legs. Trochanteral organ with triangular setal pattern and up to 22 setae. Unguis with 4 internal teeth; basal teeth located approximately middle of inner claw length (Fig.
Abdomen. Abdominal chaetotaxy reduced and slightly variable. Abd. 1 with 4 macrosetae: a5, m2, m3, and m4 (Fig.
Entomobrya unifasciata sp. n. can be diagnosed by the presence of only three dark transverse bands (no band across the posterior margin of Th. 2), presence of head mesoseta An’0, 4 macrosetae on Ab. 1, and 3 eye patch setae (see Table
Endemic to North America (Suppl. material
Body shape and color pattern. Body relatively robust and cylindrical. Color form largely monomorphic (Fig.
Head. Apical bulb of 4th antennal segment usually bilobed. Long differentiated smooth setae on ventral side of 1st antennal segment ≈3× short setae. Four prelabral setae ciliate. Ornamentation of the distal margin of the labral papillae with 2 seta or spine-like projections (Fig.
Thorax. Thoracic chaetotaxy well-developed and relatively stable. Th. 2 macrosetae a5, m1, m4, m4p, and m5 present (Fig.
Legs. Trochanteral organ with triangular setal pattern and up to 21 setae.
Abdomen. Abdominal chaetotaxy highly developed and variable. Abd. 1 with 7-10 macrosetae (Fig.
Entomobrya unostrigata can be easily diagnosed by color pattern, a thin medial longitudinal stripe from the anterior margin of Th. 2 to the posterior margin of Abd. 5, combined with the absence of macrosetae Th. 2 m2 and Abd. 3 a2 and the presence of macrosetae m5 on Th. 2 and a1 on Abd. 3 (see Table
Nearctic, Palearctic, and Australia (Suppl. material
USA: 2 on slides, Vermont, Chittenden Co., South Burlington, Vegetable garden on south side of Swift St. at intersection with Spear St. (44.4433,-73.1893), 3.viii.2003 (F. Soto-Adames); 1 on slide, Wisconsin, Dodge Co., Horicon Marsh National Wildlife Refuge, end of Dike Rd. (43.52736,-88.64381), 12.vi.2011, AK11-47.
Bayesian analysis of 179 morphological characters from 23 taxa produced a single consensus tree with high support (Fig.
Bayesian 50% majority rules consensus trees with Pseudosinella violenta as the outgroup: A phylogeny resulting from the analysis of cytochrome c oxidase I DNA sequences (complete gene, 1539 bp) from
Bayesian analysis based on combined morphology and COI (
Detailed examination of the adult chaetotaxy of 15 species of North American Entomobrya suggests that the exclusive use of chaetotaxy for species diagnosis and as phylogenetic characters can potentially cause serious confusion. This study uncovered high levels of previously undocumented intraspecific variation and asymmetry of dorsal macrosetae (Fig.
These problems are cause for concern considering the important role of dorsal chaetotaxy in diagnosis and delimitation of species in the family Entomobryidae. Many studies are based on chaetotaxy as primary (or sole) evidence for species separation, following
Post-embryonic studies that test
The phylogenies based on morphological and molecular data illustrate the effects that chaetotaxy has on phylogeny estimation. The trend of progressive evolution towards an increased number of macrosetae presented in the morphology and combined phylogenies is suspicious and may be driven by outgroup choice and character coding strategy. Entomobrya assuta and Entomobrya citrensis sp. n., sister species characterized by reduced chaetotaxy, are basal to all other Entomobrya, together with all scaled species included in the analysis (Pseudosinella, Willowsia, and Seira), which also have few macrosetae. This association is not reflected in the analysis of COI alone (
The result of the combined phylogenetic analysis (COI and morphology) of 15 species of North American Entomobrya in addition to 6 species representing 3 closely related genera (Entomobryoides, Homidia and Willowsia) and 2 outgroup species (P. violenta and S. dowlingi), generated a highly supported phylogeny of the North American Entomobryini and Willowsia. Several interesting results were observed concerning relationships among some currently recognized Entomobrya species. Entomobrya nivalis, E. intermedia, E. multifasciata, and E. atrocincta were resolved as a monophyletic clade; all are closely related but distinct species diagnosable using morphology and COI sequences. Overlapping intraspecific variation in color pattern and chaetotaxy has caused many to consider these species synonymous (See
The resulting phylogeny also raises questions regarding the generic relationships within the tribe Entomobryini (here represented by the genera Entomobrya, Entomobryoides and Homidia) and Willowsia, a closely related genus. Research concerning the systematics of these groups is limited, and most phylogenetic studies have focused on suprageneric relationships by utilizing morphology, allozymes, and/or ribosomal markers that provided limited resolution and support of generic relationships (
This study supports
Results also indicate that the genus Willowsia may be polyphyletic. A new Willowsia species (Willowsia n. sp. 1) collected in Citrus Co., Florida, is resolved as a sister species to the Entomobrya clade, while W. buski and W. nigromaculata seem to have evolved from lineages within the Entomobrya clade. Considering their world-wide distribution, presumably spread by humans, and their similarity to Asian species (
We would like to thank Ernest Bernard, R. Edward DeWalt, Christopher Dietrich, José Marcelino, and Steven Taylor for providing specimens, and the Systematics Discussion Group at the University of Illinois for their helpful suggestions and comments. Special thanks to Juraj Cech, Monique DuBray, and Benjamin Hottel for their valuable assistance in field collections. This work was supported by the Herbert H. Ross Memorial Fund and the School of Integrative Biology Enhancement Fund from the University of Illinois; a Society of Systematic Biologists (SSB) Graduate Student Research Award; the United States Department of Agriculture (Hatch program fund to R. G.); and the National Science Foundation (0956255 to F. N. S. A.). The collection of additional material was supported by the E.D.E.N. Azorean Habitats – Environmental Defense of Endangered Native Azorean Habitats (financed by The Luso-American Foundation and the Fundo Regional Ciencia e Tecnologia, Azores, PT, to José Marcelino); and the United States Department of Agriculture, Forest Service (Southern Illinois cave ecosystems: bioinventories, microbial communities & management plans grant to F. N. S. A.). We would also like to thank the Department of Entomology at the University of Illinois Urbana-Champaign and the Department of Biology at the University of Puerto Rico.
Morphology matrix
Data type: Nexus file optimized for Mesquite
Explanation note: Alignment nexus file for all morphological characters used for phylogentic analysis. This file is optimized for viewing in mesquite and includes all character state information.
Distribution maps
Data type: PDF file
Explanation note: Distribution maps: A, Entomobrya assuta; B, Entomobrya atrocincta; C, Entomobrya bicolor; D, Entomobrya citrensis sp. n.; E, Entomobrya clitellaria; F, Entomobrya decemfasciata; G, Entomobrya intermedia; H, Entomobrya jubata sp. n.; I, Entomobrya ligata; J, Entomobrya multifasciata; K, Entomobrya neotenica sp. n.; L, Entomobrya nivalis; M, Entomobrya quadrilineata; N, Entomobrya unifasciata sp. n.; O, Entomobrya unostrigata.
Photographs of type specimens
Data type: PDF file
Explanation note: Photographs of type specimens stored at the Illinois Natural History Survey, Champaign, IL. Lateral (A) and dorsal (B) views of a neo-paratype specimen of Entomobrya quadrilineata Bueker, 1939, Fountain Bluff, IL., V.15.1932, Ross & Mohr. Lateral view of a co- type specimen of Entomobrya decemfasciata