Antennal sexual dimorphism weak, Ant II and III in males only with b1 and c3 modified elements, respectively, antennal bothriotricha absent, long sensilla present in both segments. Ant IV undivided in both sexes. Head chaetae usually uniform, sometimes short, and thick. Eyes 5+5 to 8+8, ommatidia C and D small if present. Th III in males without vesicles. Large abdomen bothriotricha ABC misaligned. Posterior large abdomen with long chaetae. Ventral tube corpus of males usually modified, with 1+1 extra vesicles (other than the sacs) and/or several complex processes; corpus of females mostly with 1+1 extra vesicles; ventral tube with 0+0 or 1+1 chaetae in both sexes. Tibiotarsi I–II without any clear modifications in both sexes; tibiotarsus III of males usually with modified chaetae IIpe, IIIpi and IVpi; tibiotarsus III of females usually with modified chaetae IIIpi and IVpi; distal tibiotarsal organ of leg III absent. Ungues I and II usually more slender than the unguis III. Unguiculi I–II with a narrow lamella and a long distal filament, unguiculus III with or without the distal filament, if present, short. Dens dorsally with or without the basal appendage, chaetae E1 and J1–3 usually spiniform. Dens ventral chaetotaxy following the formula 2,3,2…1 (rarely 2,2…1 or 2,2,1…1) from the apex to the basis. Mucro narrow, inner edge serrated, outer smooth, without the chaeta (adapted and revised from Krausbauer 1898; Linnaniemi 1912; Salmon 1951; Massoud and Delamare-Deboutteville 1964; Murphy 1965; Richards 1968; Massoud and Betsch 1972; Betsch 1980; Arlé 1984; Mari Mutt 1987; Bretfeld and Gauer 1994; Bretfeld 1995, 1997, 1999, 2002; Bretfeld and Trinklein 2000; Bretfeld and Schulz 2012).

Sminthurus pumilis Krausbauer, 1898.

Worldwide (Bretfeld 1999).

Here we surveyed and compared the 46 Neotropical species of Sphaeridia (Table 1). Many species of the genus are described based mainly in the male ventral tube morphology and leg III modified chaetae, characteristics which are variable and useful for the separation of species (Bretfeld and Gauer 1994; Bretfeld 1997, 1999, 2002; Bretfeld and Trinklein 2000; Bretfeld and Schulz 2012). However, such descriptions lack further data, especially on the antennal, large and small abdomen morphology/chaetotaxy, features which may be useful alone or at least are complementary to distinguish the species.

According to Bretfeld and Gauer (1994), Sphaeridia holds four groups of species separated by the male ventral tube morphology (Table 1, Figs 1–5). The pumilis group is characterized by species usually with only 1+1 small posterior vesicles or rarely lacking such structures, without further modifications on the ventral tube (Figs 1A, 2E, 3G, 4C, 4E–F, 5E); the brevipila group is characterized by taxa with a posterior median process (usually with extra processes as well) on the ventral tube (Figs 1B–L, 2C, D, 2F, 2I–L, 3A, B, 3D–F, 3H–J, 4D, 4K, 5A–D, 5F–I); the irmleri group is represented by species with posterior and lateral complex symmetrical processes on the ventral tube (Figs 2G, H, 3C, 4A, B); and the spira group is characterized by taxa with complicated asymmetrical structures on the ventral tube (Fig. 4G–J), combined with extra modified chaetae on male tibiotarsus III.

Figure 1. 

Morphology of the ventral tube of males of Sphaeridia spp. A apex in S. aserrata Mari-Mutt, 1987 B posterior side in S. aspinosa Bretfeld & Trinklein, 2000 C posterior side in S. biclava Bretfeld & Trinklein, 2000 D posterior side in S. bivirgata Bretfeld, 2002 E posterior side in S. boettgeri Bretfeld & Gauer, 1994 F Detailed view of the anterior mandible-like processes of S. boettgeri G anterior side (apex) in S. boettgeri H apex in S. cardosi Arlé, 1984 I apex in S. cardosi (specimens from a different locality) J apex in S. carioca Arlé, 1984 K posterior side in S. catapulta L anterior side in S. cerastes Bretfeld & Gauer, 1994. Figures adapted from species’ original descriptions.

Figure 2. 

Morphology of the ventral tube of males of Sphaeridia spp. (cont.) A posterior side in S. cerastes B apex in S. cerastes C anterior side in S. chisacae Bretfeld & Gauer, 1994 D posterior side in S. chisacae E posterior side in S. coronata Bretfeld & Gauer, 1994 F posterior side in S. decemdigitata Bretfeld & Schulz, 2012 G apex in S. fibulifera Bretfeld & Gauer, 1994 H anterior side in S. fibulifera I apex in S. fluminensis Arlé, 1984 J apex in S. fluminensis (another view) K apex in S. franklinae Bretfeld & Gauer, 1994 L posterior side in S. franklinae. Figures adapted from species’ original descriptions.

Figure 3. 

Morphology of the ventral tube of males of Sphaeridia spp. (cont.) A apex in S. heloisae Arlé, 1984 B apex in S. heloisae (another specimen) C posterior side in S. irmleri Bretfeld & Gauer, 1994 D posterior side in S. lobata Bretfeld & Gauer, 1994 E posterior side in S. mandibulata Bretfeld & Gauer, 1994 F anterior side in S. mandibulata G posterior side in S. multispina Bretfeld & Schulz, 2012 H posterior side in S. panguanae Bretfeld & Schulz, 2012 I posterior side in S. paroara Arlé, 1984 J apex in S. paroara. Figures adapted from species’ original descriptions.

Figure 4. 

Morphology of the ventral tube of males of Sphaeridia spp. (cont.) A posterior side in S. peruensis Bretfeld & Schulz, 2012 B apex in S. peruensis C posterior side in S. pilleata Bretfeld & Gauer, 1994 D posterior side in S. schalleri Massoud & Delamare-Deboutteville, 1964 E posterior side in S. squamifera Bretfeld & Gauer, 1994 F anterior side in S. squamifera G apex in S. spira Bretfeld & Gauer, 1994 H apex in S. spira, detailed view of the two asymmetrical lobes I posterior side in S. sturmi Bretfeld & Gauer, 1994 J apex in S. sturmi K posterior side in S. torifera Bretfeld & Schulz, 2012. Figures adapted from species’ original descriptions, with the exception of S. schalleri which was adapted from Bretfeld (1997).

Figure 5. 

Morphology of the ventral tube of males of Sphaeridia spp. (cont.) A apex in S. torifera B posterior side in S. tropica Bretfeld & Schulz, 2012 C detail of the apex of the posterior side in S. tropica D detail of the apical lobes in S. tropica E posterior side in S. tschirnhausi Bretfeld & Schulz, 2012 F posterior side in S. vampyra Bretfeld & Schulz, 2012 G lateral side in S. vampyra, detail of the posterior median plane H lateral side in S. vampyra, detail of the posterior lateral plane I posterior side in S. winteri Massoud & Delamare-Deboutteville, 1964. Figures adapted from species’ original descriptions, with the exception of S. winteri which was adapted from Bretfeld (1997).

In our survey of the Neotropical Sphaeridia we noticed that at least eight species do not have enough characters to clearly differ them from other congeners or to keep them in the genus, and so we are considering them as species inquerendae. These taxa are S. aspinosa Bretfeld & Trinklein, 2000, S. biniserrata (Salmon, 1951) sensu Massoud & Delamare-Deboutteville (1964), S. delamarei Bretfeld, 1997, S. duckei Bretfeld, 2002, S. gladiolifer Delamare-Deboutteville & Massoud, 1964, S. martii Bretfeld & Gauer, 1994, S. multispina Bretfeld & Schulz, 2012 and S. serrata (Folsom & Mills, 1938). Sphaeridia aspinosa and S. multispina males do not present the typical clasper organ with modified Ant II and III chaetae seen in all other Sminthurididae. Bretfeld and Trinklein (2000: 190) and Bretfeld and Schulz (2012: 515) suggested these specimens could be anomalous, but they had few specimens of both species to confirm such condition as abnormal. Also Bretfeld and Trinklein (2000: 190) suggested the absence of the clasper could imply that S. aspinosa, and consequently S. multispina, may belong to an undescribed different basal genus of the family, which makes these species not comparable with the other taxa of Sphaeridia and their descriptions in need for a revision. Sphaeridia duckei was described based on a single female with different features from those seen in all other Sminthurididae, like capitate tenent hairs in all pairs of legs and trunk bothriotricha ABC aligned, which may indicate this specimen may be a subadult of another family, like Bourletiellidae. It is worth noting that Bretfeld (1999:52) suggested that the records of the type species of Sphaeridia must be confirmed with males, because the females do not show differences in many species, supporting our view of S. duckei. On the other hand, S. biniserrata, S. delamarei, S. gladiolifer and S. serrata likely belong to Sphaeridia, but their descriptions lack sufficient information about the antennae, legs and/or ventral tube to clearly separated them from other taxa, which makes comparisons with other species arbitrary (see Table 1). Finally, S. martii does not fit in Sphaeridia since the morphology of its male antennae is more complex compared to other taxa, presenting modified chaetae b1–b3 on Ant II and c1–c3 on Ant III. Even with this observation, its placement among the Sminthurididae is still unclear. So we believe all these species need redescriptions and a revision of their placement within the family.

Holotype male on slide, Brazil, Piauí state, Piracuruca municipality, Sete Cidades National Park, ‘Primeira Cidade’ (4°05'42.53"S, 41°40'50.7"W), 168 m, in sandy soil, ecotonal zone between Caatinga and Cerrado biomes, 14/V/2021, A.M.N. Silva col., pitfall traps. Paratypes on slides: one male, one female, and one juvenile, with the same data of the holotype.

Male specimens with a pale purple body, antennae dark purple (Fig. 6A). Males Ant II with two spiniform microsensilla plus six long chaetae other than b1, Ant III with two or three spiniform microsensilla plus four long chaetae other than c3. Head without any medial chaeta, with 1+1 zones without cuticular granulation between the antennae. Medial prelabral chaetae longer than others in both sexes. Femur I and III with two and one curved chaetae, respectively. Tibiotarsus III of males with a IIpe chaeta leaf-shaped inserted in a large papilla (Fig. 6B), tibiotarsus III of females with Ipi, IIpi, IIIpi, and IVpi chaetae serrated. Ungues I–III without tunica or pseudonychia. Dorsal anal valve with three unpaired chaetae (as1, ms1, and ps1). Parafurcal area with seven chaetae. Tenaculum with 1+1 chaetae. Ventral tube in males highly modified with several apical processes, two of them in the posterior region lamellated (striated), with 1+1 chaetae (Fig. 6C), female ventral tube with 1+1 apical vesicles plus 1+1 chaetae (Fig. 6D). Dorsal dens with a basal appendage (Fig. 6E), J1–3 and E1 chaetae spiniform, ventral formula as 2,3,2...1 from the apex to the basis.

Figure 6. 

Sphaeridia piauiensis sp. nov. A habitus of a male in ethanol (dorsal view) B leaf-shaped chaeta on dorsal tibiotarsus III of a male C male ventral tube (apex) D female ventral tube (apex), arrow points to a vesicle E female dens, arrow points to the basal appendage.

Body (head + trunk) length of the type series ranging between 228 and 571 µm, holotype with 269 µm, male average size = 248 µm, female average size = 280 µm, entire type series average size = 259 µm. Male specimens with a pale purple body, antennae dark purple (Fig. 6A). Female color pattern unknown (studied specimen already on a glass slide).

Head (Figs 7, 8). Antennae length 202 µm in the holotype. Holotype antennal segment ratio I:II:III:IV as 1:2.3:1.7:5.9. Males’ antenna: Ant I with six chaetae (Fig. 7A). Ant II with element b1 as a thick spine in a large papilla, plus 16 regular chaetae, six of them longer than others (three of them on basal half and three of them on distal half), plus two spiniform microsensilla (Fig. 7A). Ant III with element c3 present as a thick spine in a papilla, plus 12 regular chaetae, four of them longer than others (two on basal half and two on distal half), plus two or three spiniform microsensilla; apical organ sensory rods in two independent shallow invaginations (Fig. 7A). Ant IV longer than Ant III, undivided, with ~ 61 chaetae, ~ 8 of them as a curved subapical sensilla (Fig. 7B). Females’ antenna: Ant I with six chaetae (Fig. 7C). Ant II with 10 chaetae (Fig. 7C). Ant III with 10 chaetae, plus one apical spiniform microsensilla; apical organ sensory rods in two independent shallow invaginations (Fig. 7C). Ant IV longer than Ant III and undivided, with ~ 54 chaetae, ~ 7 of them as curved subapical sensilla (Fig. 7D). Head capsule (both sexes): Eyes 8+8 plus one interocular chaeta, head capsule normal (not elongated) (Fig. 8A). Clypeal area a–f lines with 3/6/3–4/4/4/5 dorsal + ventral chaetae, respectively (Fig. 8A, B). Interantennal area α and β lines with 2/2 chaetae, respectively; frontal area A–E lines with 1/1/1–2/1/2 chaetae, respectively; 1+1 interocular chaetae present; 1+1 zones without cuticular granulation present between the antennae (Fig. 8A). Labial basomedian and basolateral fields with three chaetae each (Fig. 8C). Six prelabral chaetae present, medial chaetae longer and thicker than the others (Fig. 8C); labral p, m, and a lines with 4, 5, 4 chaetae, respectively; each chaeta of a line in an individual papilla (Fig. 8D). Mandibles normal (not elongated), with 4+5 incisive apical teeth (Fig. 8E). Maxillae and labial palp papillae unclear. Anterior head, labrum, labium, and visible mouthparts without any clear sexual dimorphism.

Figure 7. 

Sphaeridia piauiensis sp. nov. antenna (dorsal view) A, B male antenna A Ant I–III B Ant IV C, D female antenna C Ant I–III D Ant IV.

Figure 8. 

Sphaeridia piauiensis sp. nov. head A male anterior head chaetotaxy (eyes omitted), arrow points to a chaeta which can be present or absent B male labial and post-labial (ventral) chaetotaxy C male labral chaetotaxy D male mandibles apexes (incisive teeth).

Trunk (Figs 9, 10). Large abdomen: thorax continuous with the abdomen, without clear segmentations in both sexes. Males: Th II with one a chaeta inside a cavity and two m chaetae; Th III with two a and two m chaetae; Abd I without chaetae, Abd II with bothriotricha A, B, and C slightly misaligned, with two a, three m, and three p regular chaetae near the bothriotricha; Abd III–IV with three main lines of chaetae above the bothriotrichum C: dII-1 with five, dIII-1 with five, dV-1 with three, plus two lateral chaetae under the bothriotrichum C (Fig. 9A). Parafurcal area with four rows of chaetae with two, two, one, and two (total of seven) chaetae, neosminthuroid chaetae absent (Fig. 10A). Females: Th II with one a chaeta inside a cavity and two m chaetae; Th III with two a and two m chaetae; Abd I without chaetae, Abd II with bothriotricha A, B, and C slightly misaligned, with two a, three m, and three p regular chaetae near the bothriotricha; Abd III–IV with four main lines of chaetae above the bothriotrichum C: dI-1 with seven, dII-1 with five, dIII–1 with five, dV–1 with three, plus two lateral chaetae under the bothriotrichum C (Fig. 9B). Parafurcal area with four rows of chaetae with two, two, one, and two (total of seven) chaetae, neosminthuroid chaetae absent (Fig. 10C). Small abdomen: including Abd V–VI in both sexes. Males: Abd V with bothriotricha D and E present, plus two regular chaetae. Dorsal anal valve with as1–3, ms1–3, and ps1–2 chaetae, as1, ms1, and ps1 unpaired; each ventral anal valve with aai1, ai1–3, ami1 (as an oval organ lacking any inner sensillum), mi1–2, mpi1, and pi1–3 chaetae (Fig. 10B). Females: Abd V with bothriotricha D and E present, plus two regular chaetae. Dorsal anal valve with as1–3, ms1–3, and ps1–2 chaetae, as1, ms1, and ps1 unpaired; each ventral anal valve with aai1, ai1–3, ami1 (as an oval organ lacking any inner sensillum), mi1–3, mpi1, and pi1–3 chaetae (Fig. 10C). Genital plate chaetotaxy unclear in both sexes.

Figure 9. 

Sphaeridia piauiensis sp. nov. large abdomen A male B female.

Figure 10. 

Sphaeridia piauiensis sp. nov. parafurcal area and small abdomen A male parafurcal area B male small abdomen C female parafurcal area and small abdomen.

Abdominal appendages (Fig. 11). Ventral tube in males symmetrical, with at least three anterior projections and at least eight posterior projections, two of them lamellated (striated), with 1+1 distal chaetae on lateral flaps (Fig. 11A), females with 1+1 vesicles and 1+1 distal chaetae (Fig. 6D). Tenaculum ramus with three teeth, each plus an apically rounded basal appendix, corpus with 1+1 chaetae. Manubrium with four dorsal chaetae (Fig. 11B); dens with a basal appendage and 15 dorsal (posterior) chaetae, lines E/P/PJ/J with 2/2/8/3 chaetae, respectively; J line and E1 chaeta as thick acuminated spiniform chaetae (Fig. 11D); dens ventrally (anteriorly) with eight chaetae, following the formula from the apex to the basis: 2,3,2...1 (Fig. 11C). Mucro narrow with a broad apex, with an external lamella smooth and an internal lamella serrated with ~ 22 teeth; mucronal chaeta absent (Fig. 11D). Furca without any clear sexual dimorphism. Manubrium:dens:mucro ratio of the holotype = 3.3:6.4:1.

Figure 11. 

Sphaeridia piauiensis sp. nov. male abdominal appendages A ventral tube (lateral view) B manubrial chaetotaxy (lateral view) C ventral dens chaetotaxy D dorsal dens chaetotaxy and mucro.

Legs (Fig. 12). Leg I: coxa with one chaeta; trochanter with two chaetae; femur with 11 chaetae, two of them as curved chaetae; tibiotarsus with 34 chaetae and two oval organs (O2pe, O2ae), whorls I/II/III/IV/V with 9/8/7/5/5 chaetae respectively (Fig. 12A, B). Leg II: coxa with one chaeta; trochanter with two chaetae; femur with 10 chaetae; tibiotarsus with 34 chaetae and two oval organs (O2pe, O2ae), whorls I/II/III/IV/V with 9/8/7/5/5 chaetae, respectively (Fig. 12C, D). Leg III: coxa with two chaetae; trochanter with four chaetae; femur with 11 chaetae, one as a short curved chaeta; tibiotarsus in males with 36 chaetae and two oval organs (O2pe, O2ae), chaeta IIpe leaf-shaped in a papilla plus two regular chaetae, whorls I/II/III/IV/V with 9/9/7/6/5 chaetae respectively (Fig. 12E, F); tibiotarsus in females with 35 chaetae and two oval organs (O2pe, O2ae), chaetae Ipi, IIpi, IIIpi and IVpi serrated, whorls I/II/III/IV/V with 9/8/7/6/5 chaetae respectively (Fig. 12G). Oval organs of all tibiotarsi in both sexes with a tiny inner sensillum, each (not represented in the figures). Foot complexes: pretarsi I–III with anterior and posterior chaetae each; ungues I–II more slender than the unguis III, with one dorsal unpaired tooth and one internal unpaired tooth, ungues without tunica and pseudonychia; unguiculi I–III without teeth, with all lamellae smooth, unguiculi filament pre-apical and reaching the apex of the ungues in legs I and II, absent in leg III; ratio of ungues I–III in the holotype = 1:0.97:0.96.

Figure 12. 

Sphaeridia piauiensis sp. nov. male legs A coxa, femur, and trochanter of leg I B tibiotarsus and empodial complex of leg I C coxa, femur, and trochanter of leg II D tibiotarsus and empodial complex of leg II E coxa, femur and trochanter of leg III F tibiotarsus and empodial complex of leg III G tibiotarsus and empodial complex of leg III of the female.

The species was named after its type locality, Piauí State, Brazil.

Sphaeridia piauiensis sp. nov. belongs to the irmleri group sensu Bretfeld and Gauer (1994) due to its complex male ventral tube without asymmetrical structures or medial processes. The irmleri group holds only three Neotropical species: S. irmleri Bretfeld & Gauer, 1994, S. fibulifera Bretfeld & Gauer, 1994, and S. peruensis Bretfeld & Schulz, 2012. Although they resemble S. piauiensis sp. nov. by the complex male ventral tube, S. irmleri and S. fibulifera males have a smooth and long chaeta IIpe on tibiotarsus III, while males of S. piauiensis sp. nov. and S. peruensis have a leaf-shaped IIpe chaeta. Regarding the tibiotarsal chaetotaxy, S. piauiensis sp. nov. differs from S. peruensis by presenting the tibiotarsus III IIIpi chaeta of normal shape in males and ventral tube with 1+1 chaetae, while S. peruensis presents tibiotarsus III IIIpi chaeta forked in males and the absence of ventral tube chaeta. Also S. peruensis presents two pairs of hooks on the furca (a pair on the manubrium and another on the dens), while they are absent in S. piauiensis sp. nov. The leaf-shaped chaeta on the tibiotarsus III of the male is also seen in the Brazilian species S. heloisae Arlé, 1984, but this species belongs to the brevipila group due to the presence of a posterior medial process on the male ventral tube, absent in S. piauiensis sp. nov. The female of S. piauiensis sp. nov. presents the tibiotarsus III chaeta Ipi toothed, which makes it the sole species from the Neotropical Region with such recorded morphology. Additionally, the new species does not present the chaeta p0 in the labral region (Fig. 8C), something unusual to other Symphypleona genera. However, this information is mostly undescribed for other species of Sphaeridia, so it is not clear if it has any value as a specific diagnostic trait.

Males with highly dimorphic antennae, Ant II with Tra1–2, b1–b7 elements, b1–b6 together, b7 isolated, Ant III with Tra3 as a bothriotrichum or a regular chaeta, elements c1 and c3 always present. Ant IV undivided in both sexes, usually with blunt sensilla. Eyes 6+6 to 8+8. Th III and large abdomen in males without vesicles. Bothriotricha ABC misaligned. Posterior large abdomen with or without long chaetae. Ventral tube without modifications. Each anal valve with 0–2 barbulated spines in both sexes. Tibiotarsus I proximal organ usually present in males, formed by four modified sensilla. Tibiotarsus II with or without a polycarinate chaeta. Tibiotarsus III with 0–5 serrated spines in both sexes. Distal tibiotarsal organ on leg III absent. Dens lacking spine-like chaetae. Mucro narrow, inner edge serrated, outer smooth, mucronal chaeta present (adapted and revised from Börner 1908; Denis 1925; Denis 1931; Folsom 1932; Snider 1988; Palacios-Vargas 1995; Palacios-Vargas and Bernava 1999; Palacios-Vargas 2007; Ospina and Palacios-Vargas 2009; Schulz and van Harten 2013; Palacios-Vargas et al. 2018).

Sminthurides seurati Denis, 1925.

Americas, Africa, and Indo-Asia (Bellinger et al. 1996–2023).

Denisiella species arguably have the most sexually dimorphic antennae among all the Sminthurididae, with several modified elements on the male claspers (Massoud and Betsch 1972; Betsch 1980; Medeiros et al. 2022). The morphology of such elements varies between the species (Fig. 13), but even so, most of them are present, with the exception of the c2 element on Ant III, which may be absent in some species (Börner 1908; Denis 1931; Palacios-Vargas and Bernava 1999; Schulz and van Harten 2013), and Tra3 on Ant III, which interchanges between a regular chaeta or a bothriotrichum (Denis 1925; Palacios-Vargas 1995; Palacios-Vargas et al. 2018) (Table 2).

Figure 13. 

Chaetotaxy of Ant II and III of males of Denisiella A D. betschi Palacios-Vargas, Ferreira & Zeppelini, 2018 B D. caatingae Palacios-Vargas, Ferreira & Zeppelini, 2018 C D. colombiana Ospina & Palacios-Vargas, 2009 D D. diomedesi Palacios-Vargas, 2007 E D. lithophila Snider, 1988 F D. maesorum Palacios-Vargas, 1995 G D. ramosa (Folsom, 1932) H D. rhizophorae Palacios-Vargas, Ferreira & Zeppelini, 2018 I D. seurati (Denis, 1925) (ventral view). Figures adapted from species’ original descriptions.

In the same way as to many other Sminthurididae, including Sphaeridia, the diagnosis and comparisons between Denisiella taxa is mostly based on males’ morphology. Because of this, some Denisiella descriptions lack data on the females’ morphology, especially regarding the antennal and abdominal chaetotaxy (Börner 1908; Denis 1931; Palacios-Vargas 2007; Schulz and van Harten 2013; Palacios-Vargas et al. 2018). In our survey we observed D. nayarita Palacios-Vargas and Bernava, 1999 and D. sexpinnata (Denis, 1931) were described based only on females, while their males’ morphology is completely unknown. So, we suggest both taxa as species inquirendae, as their identities are not fully clear and it is not possible to clearly distinguish them from other taxa, especially from those described based only on male morphology. In a similar way, D. serroseta (Börner, 1908) description lacks information about the male antennae, small and large abdomen of both sexes, and shows unclear data on the chaetotaxy of legs and furca. In this scenario this description does not fit the current taxonomy of Sminthurididae and does not allow us to clearly separate the species from its congeners; therefore, we also suggest D. serroseta as a species inquirenda.

Some species of Denisiella can be readily distinguished from several others by the presence/absence of a unique feature located between de clypeal and interantennal areas of male head, the nasal organ (Palacios-Vargas et al. 2018). Since this structure is formed by strongly modified projections, we believe it may have a phylogenetical significance and probably points to different lineages within the genus. So here we tentatively separate the genus in two distinct groups: the seurati group, for the species without the nasal organ, holding: D. betschi Palacios-Vargas, Ferreira & Zeppelini, 2018, D. colombiana Ospina & Palacios-Vargas, 2009, D. lithophila Snider, 1988, D. maesorum Palacios-Vargas, 1995, D. ramosa Folsom, 1932, D. rhizophorae Palacios-Vargas, Ferreira & Zeppelini, 2018, D. seurati Denis, 1925, D. serroseta Börner, 1908 and D. piracurucaensis sp. nov.; and the diomedesi group, for the species with the nasal organ, with the species: D. bretfeldi, Schulz & van Harten, 2013, D. caatingae Palacios-Vargas, Ferreira & Zeppelini, 2018 and D. diomedesi Palacios-Vargas, 2007.

Holotype : male on slide, Brazil, Piauí state, Piracuruca municipality, Sete Cidades National Park, ‘Primeira Cidade’ (4°05'42.53"S, 41°40'50.7"W), 168 m, in sandy soil, ecotonal zone between Caatinga and Cerrado biomes, 14/V/2021, A.M.N. Silva col., pitfall traps. Paratypes three males and four females on slides.

Male head and trunk uniformly dark purplish, legs, furca and antennal bases pale, distal Ant I and Ant II–IV purplish (Fig. 14A). Male Ant II with 11, Ant III with seven long blunt sensilla, respectively, Tra3 as a regular chaeta, Ant IV with 19 sensilla. Female Ant II and Ant III with spiniform chaetae, Ant IV with eight sensilla. Eyes 8+8. Frontal head with acuminate spiniform chaetae, longer in the females (Fig. 14B). Nasal organ absent. Female anal valves with ps2, pi1 and pi3 as barbulated chaetae (Fig. 14C). Parafurcal area with 10 chaetae in both sexes. Each tenaculum ramus with three teeth, corpus with 1+1 chaetae (Fig. 14D). Males with four campaniform chaetae on the proximal tibiotarsal organ in leg I. Polycarinate chaeta on tibiotarsus II absent. Tibiotarsus III chaetae IIpi, IIIpi, IVpi, and Vpi serrated (Fig. 14E). Dorsal dens J chaetae enlarged at their bases, somewhat spiniform, ventral chaetotaxy formula from the apex to the basis as 3,3,3,3,2,1,1,1 or 3,3,3,3,2,1…1.

Figure 14. 

Denisiella piracurucaensis sp. nov. photographs A habitus of a male in ethanol (dorsal view) B habitus of a female in slide (lateral view) C barbulate chaeta in the small abdomen of a female D tenaculum of a female E serrate chaeta on the tibiotarsus III of a male.

Body (head + trunk) length of the type series ranging between 0.41 and 1.4 µm, holotype with 0.5 µm, male average size = 0.52 µm, females average size = 1.1 µm, entire type series average size = 0.85 µm. Male head and trunk uniformly dark purplish, legs, furca and antennal bases pale, distal Ant I and Ant II–IV purplish (Fig. 14A). Female color pattern unknown (studied specimens already on glass slides).

Head (Figs 15–16). Antennae length: 0.32 µm in the holotype. Holotype antennal segments ratio I:II:III:IV as 1.0:1.1:0.5:1.6. Male antenna: Ant I elongated with seven chaetae, two smaller at the apex, two other apical chaetae thicker than the others (Fig. 15A). Ant II with 11 regular chaetae, 11 long blunt sensilla, two bothriotricha (Tra1, Tra2), one microsensillum, modified chaetae b1, b3 and b6 on the anterior tubercle, b2, b4 and b5 on the posterior tubercle, b7 thick, apically flattened and granulated (Fig. 15B). Ant III with eight regular chaetae, one of them as a bifurcated chaeta in one antenna of a single specimen, seven long blunt sensilla, three microsensilla, Tra3 as a regular chaeta, apical organ sensory rods in one single shallow invagination, modified chaetae c1–3 present, c1 thick, apically flattened, and grainy, c2 as a small blunt projection and c3 as a thick smooth spine in a papilla with at least one cuticular spine between c1 and c3 (Fig. 15C). Ant IV with ~ 58 regular chaetae, plus 19 blunt sensilla (Fig. 15D). Female antenna: Ant I short with seven chaetae, two smaller at the apex, two other apical chaetae thicker than the others (Fig. 15E). Ant II with 12 chaetae (Fig. 15F), five of them regular, seven somewhat spiniform. Ant III with 13 chaetae, six of them somewhat spiniform, plus one apical microsensillum; apical organ sensory rods in a single invagination (Fig. 15G). Ant IV longer than Ant III, with ~ 52 regular chaetae, plus eight blunt sensilla (Fig. 15H). Head capsule (both sexes): Eyes 8+8, with two interocular chaetae, head capsule normal (not elongated) (Fig. 16A, B). Clypeal area a–f lines with 8/6/5/4–5/6/6 chaetae, respectively. Interantennal area α and β lines with 2/1 chaetae, respectively; frontal area A–E lines with 2/1/1/1/2 chaetae, respectively, frontal spiniform chaetae of females longer than in the males (Fig. 16A–C). Labial basomedian field with four chaetae, basolateral field with five (Fig. 16C). Six prelabral chaetae long and thick (Fig. 16A, B); labral p, m, and a lines with 5/5/4 thick chaetae, respectively; each a line chaeta in a single papilla; labral papillae present as small spines, labral apex cuticle with six pointed projections (Fig. 16D). Mandibles normal (not elongated), with 4+4 incisive apical teeth (Fig. 16E). Maxillae normal (not elongated) (Fig. 16F). Labrum, labium, and mouthparts without any clear sexual dimorphism.

Figure 15. 

Denisiella piracurucaensis sp. nov. antenna (dorsal view) A–D male antenna A Ant I B Ant II C Ant III D Ant IV E–H female antenna E Ant I F Ant II G Ant III H Ant IV.

Figure 16. 

Denisiella piracurucaensis sp. nov. head A male anterior head cheatotaxy (eyes omitted) B female anterior head cheatotaxy, arrow indicates a chaeta which can be present or absent C male labial and post-labial (ventral) chaetotaxy D male labral chaetotaxy E female mandibles apexes (incisive teeth) F female left maxilla capitulum.

Trunk (Fig. 17). Large abdomen: thorax continuous with the abdomen, without clear segmentations in both sexes (Fig. 17A, B). Male: Th II with one a and one m chaetae; Th III with two a and three m chaetae; Abd I without chaetae; Abd II with bothriotricha A, B, and C misaligned, with two a, two m, and two p regular chaetae; Abd III–IV with three main lines of chaetae above the bothriotrichum B: dI–1 with four, dII–1 with two, dIII–1 with three chaetae respectively, plus seven chaetae below the bothriotrichum B (Fig. 17A). Parafurcal area in males with 10 chaetae in four rows of chaetae, with three, two, three, and two chaetae, respectively, neosminthuroid chaetae absent (Fig. 17B). Female: Th II with one a and one m chaetae; Th III with two a and two m chaetae; Abd I without chaetae; Abd II with bothriotricha A, B, and C misaligned, with two a, three m, and two p regular chaetae; Abd III–IV with four main lines of chaetae above the bothriotrichum B: dI–1 with eight, dII–1 with seven, dIII–1 with three and dIV–1 with three respectively, plus seven chaetae below the bothriotrichum B. Dorsal chaetae longer than in the males (Figs 14B, 17C). Parafurcal area in females with 10 chaetae in four rows, with three, two, three, and two chaetae, respectively, three internal somewhat spiniform (Fig. 17D). Small abdomen: including Abd V–VI in both sexes (Fig. 17E, F). Male: Abd V with bothriotricha D and E. Dorsal anal valve with as1–3, ms1–3, mps1, and ps1–2 chaetae, ps2 barbulated; as1, ms1, and ps1 unpaired; each ventral anal valve with aai1–2, ai1–3, ami1 (as an oval organ lacking any inner sensillum), mi1–5, mpi1 and pi1–3 chaetae, pi1 barbulated (Fig. 17E). Female: Abd V with bothriotricha D and E present. Dorsal anal valve with as1–3, ms1–4, mps1, and ps1–2 chaetae, ps2 barbulated (Fig. 17F); as1, ms1, and ps1 unpaired; each ventral anal valve with aai1–5, ai1–3, ami1 (as an oval organ lacking any inner sensillum), mi1–5, mpi1 and pi1–3 chaetae present, pi1 and pi3 barbulated (Figs 14C, 17F). Genital plate unclear in both sexes.

Figure 17. 

Denisiella piracurucaensis sp. nov. trunk A male large abdomen B male parafurcal area C female large abdomen D female parafurcal area E male small abdomen F female small abdomen.

Abdominal appendages (Fig. 18A, B). Ventral tube with 1+1 chaetae. Each tenaculum ramus with three teeth plus an apically rounded basal appendix, corpus with 1+1 chaetae (Fig. 14D). Manubrium with 8+8 dorsal chaetae. Dens with a basal appendage and 46 dorsal (posterior) chaetae, lines E/PE/P/JP/JPJ/J with 4/9/10/12/5/6 chaetae, respectively; J line chaetae enlarged at their bases, somewhat spiniform (Fig. 18A); dens ventrally (anteriorly) with 17 chaetae, following the formula from the apex to the basis: 3,3,3,3,2,1,1,1 or 3,3,3,3,2,1…1 (Fig. 18B). Mucro narrow, with an external lamella smooth and an internal lamella serrated with ~ 22 teeth, mucronal chaeta present (Fig. 18A). Furca without any clear sexual dimorphism. Manubrium:dens:mucro ratio of the holotype = 1.0:2.5:0.76.

Figure 18. 

Denisiella piracurucaensis sp. nov. trunk appendages A female dorsal dens chaetotaxy and mucro B female dorsal dens chaetotaxy, arrow indicates a chaeta which can be present or absent C female coxa, trochanter, femur, tibiotarsus and empodial complex of leg I, detail shows the campaniform sensilla of males D female coxa, trochanter, femur, tibiotarsus and empodial complex of leg II E female coxa, trochanter, femur, tibiotarsus and empodial complex of leg III, detail shows the unguiculus filament (present or absent) of males.

Legs (Fig. 18C–E). Leg I: epicoxa and subcoxa without chaetae, coxa with one chaeta; trochanter with three chaetae; femur with 11 chaetae, two of them curved; tibiotarsus with 36 chaetae and two oval organs (O2pe, O2ae), whorls I/II/III/IV/V with 9/8/7/7/5 chaetae respectively, chaeta IIpi serrated; male proximal four chaetae IVe, IVae, Ve, and Vae modified into campaniform sensilla (Fig. 18C). Leg II: epicoxa with one chaeta, subcoxa without chaetae, coxa with one chaeta; trochanter with three chaetae; femur with 12 chaetae; tibiotarsus with 37 chaetae and two oval organs (O2pe, O2ae), whorls I/II/III/IV/V with 9/8/7/7/6 chaetae respectively (Fig. 18D). Leg III: epicoxa with one chaeta, subcoxa with one chaeta, coxa with three chaetae (two regular and one small); trochanter with three chaetae; femur with 11 chaetae, one of them curved; tibiotarsus with 38 chaetae and two oval organs (O2pe, O2ae), whorls I/II/III/IV/V with 9/8/8/7/6 chaetae respectively; chaetae IIpi, IIIpi, IVpi, and Vpi serrated (Figs 14E, 18E). Oval organs of all tibiotarsi in both sexes with a tiny inner sensillum, each (not represented in the figures). Foot complexes: pretarsi I–III with an anterior and a posterior chaetae each; ungues I–III subequal in shape, with one dorsal unpaired tooth, a pair of basal lateral teeth and one medial internal tooth; unguiculi I–III somewhat truncate, without teeth, with all lamellae smooth. Female unguiculi apical filament surpassing the apex of the ungues in legs I–III; male unguiculi apical filament surpassing the apex of the ungues in legs I and II, unguiculus III apical filament absent or reduced in leg III; ratio of ungues I–III in the holotype = 1.0:0.9:0.8.

The species was named after its type locality, Piracuruca municipality, Piauí state, Brazil.

As said before, D. piracurucaensis sp. nov. belongs to the seurati group due to the absence of the nasal organ on males. Within this group, it is more similar to D. betschi, D. colombiana, D. maesorum and D. rhizophorae due to the presence four serrated spines on the tibiotarsus III. It looks more similar to D. colombiana by the presence of spiniform chaetae at least on Ant II of the female and a similar ventral dens chaetotaxy. Even so, the new species can be separated from all of these taxa especially by the presence of 8+8 eyes (6+6 in the other species), ps1 and pi1 as barbulated chaetae on the male anal valves (both regular chaetae in D. betschi and D. rhizophorae, only pi1 and pi3 as barbulated chaetae in D. colombiana), and the absence of a polycarinate chaeta on the male tibiotarsus II (present in D. betschi, D. colombiana, and D. rhizophorae). Further comparisons are presented in Table 2.