Entomobryinae Schäffer, 1896 sensu Zhang & Deharveng 2015

Viana, Stéphanie Dos Santos, Morais, José Wellington De & Cipola, Nikolas Gioia, 2024, Taxonomic revision of Entomobrya Rondani, 1861 (Collembola: Entomobryidae: Entomobryinae) from the Brazilian Amazon, Zootaxa 5452 (1), pp. 1-110 : 8-18

Subfamily Entomobryinae Schäffer, 1896 sensu Zhang & Deharveng 2015

Genus Entomobrya Rondani, 1861

Type species. Entomobrya muscorum (Nicolet, 1842) : 75, pl. 8, Fig. 10, Europe, probably Switzerland ( Jordana 2012: 147). Distribution of the type species. Holarctic ( Jordana 2012; Mari-Mutt et al. 1997 –2021; Bellinger et al. 1996 –2024).

Diagnosis of genus. Body unscaled with mic and mes abruptly ciliate; mac and mes finely ciliate, apically acuminate or foot-shaped, short or elongated ( Fig. 2); Ant I without subdivisions; Ant IV apical bulb present or absent ( Fig. 4B); prelabral chaetae smooth or ciliate, simple or rarely bifurcate ( Figs 6A, 49D); four labral papillae ( Fig. 6B); eyes 8 per side ( Fig. 5); dorsal macrochaetotaxy dense or reduced ( Figs 25, 51); intersegmental membranes smooth, lacking chaetae; tibiotarsus I–III outer sides with a row of mac finely ciliate ( Fig. 33E); dens distally crenulate and eventually with one to two rows of modified chaetae ( Fig. 19D), inner side without spines; mucro laterally flattened and with 2 teeth (proximal and distal) projected dorsally, plus 1 proximal spine ( Fig. 11B) (adapted and updated from Rondani 1861; Christiansen 1958b; South 1961; Jordana & Baquero 2005; Jordana 2012; Bellini et al. 2015; Santos et al. 2020; Viana et al. 2022).

Remarks. All Entomobrya species from the Brazilian Amazon herein studied (except E. linda and E. bicyana sp. nov.) resemble at some extent two other Entomobryinae genera, Entomobryoides Maynard, 1951 and Amazhomidia Cipola & Bellini, 2016 in Cipola et al. 2016a ( Maynard 1951; Cipola et al. 2016a, 2018b). They are more similar to Entomobryoides by Ant IV apical bulb absent ( Fig. 4B), labial papilla E l.p. exceeding the base of a.a. (only in E. uambae ), and tibiotarsus inner side with two rows of modified chaetae. However, we believe these characteristics do not clearly support Entomobryoides , since there are at least five species of Entomobrya with the apical bulb on Ant IV, but also with modified chaetae on the tibiotarsus, like: Entomobrya murreensis Yosii & Ashraf, 1965 , E. nigritella Yosii & Ashraf, 1965 , E. arborea ( Tullberg, 1871) , E. caesarea Latzel, 1917 and E. tristriata Ma & Chang, 2020 (see Yosii & Ashraf 1965: 156–157; Jordana 2012: 209; Chang et al. 2020: 336). Furthermore, considering that the tibiotarsal modified chaetae are present in many Entomobryoidea genera ( Cipola et al. 2017, 2018a, 2020, 2022; Cipola & Greenslade 2023), if not in the majority, it is more likely that this characteristic is homoplastic or even plesiomorphic when compared between the taxa.

Other features, including the presence or absence of an apical bulb on Ant IV, are not sufficient for separating taxa at the generic or subgeneric level, at least to some taxa of Entomobryinae and Lepidocyrtinae ( Cipola et al. 2017, 2018b, 2018c). This is also the case of the size of labial papilla E l.p., whose morphology changes in different species, as observed in some genera of Entomobryidae ( Jordana 2012; Cipola et al. 2017, 2018b). This is the case of E. uambae compared to other Entomobrya spp. in the present study. Furthermore, it is necessary to consider that Entomobryoides does not have an annulated Ant IV and smooth and bifurcate prelabral chaetae, like the specimens studied here, so we believe it is inconsistent to include E. paroara , E. egleri , E. uambae , E. acreanenis sp. nov., E. albitrigona sp. nov., E. bicyana sp. nov., E. elizeuli sp. nov., E. idenilzae sp. nov. and E. pseudomaculata sp. nov. in Entomobryoides . Such characteristics are also present in Amazhomidia , a genus which differs from Entomobrya by scaled body, cephalic groove without scale-like chaetae, and dens with dorsal spines ( Cipola et al. 2016a).

The presence of smooth and bifurcate prelabral chaetae is an atypical feature within Entomobrya ( Jordana 2012; Katz et al. 2015; Viana et al. 2022), but we find it more coherent to keep E. paroara , E. egleri , E. uambae , E. acreanenis sp. nov., E. albitrigona sp. nov., E. bicyana sp. nov., E. elizeuli sp. nov., E. idenilzae sp. nov. and E. pseudomaculata sp. nov. in Entomobrya , at least until these species can be studied in a phylogenetic perspective. To date, the phylogenetic relationships of most species of Entomobrya and Entomobryoides have yet to be properly tested ( Zhang & Deharveng 2015; Zhang et al. 2019), including of course the species studied here.

Morphological description of Entomobrya species from the Brazilian Amazon

The following characters are shared by the Entomobrya species herein studied and are not repeated in the descriptions:

Dorsal chaetae and structure. Bothriotricha ( Fig. 3B).Thin and densely ciliated by elongated cilia, short on head (1 post-ocellar) and elongated on Abd II–IV, with formula 2 (a5, m2), 3 (a5, m2, m5), 2 (T2, T4) respectively.

Mac ( Fig. 5). Finely ciliate and apically foot-shaped (strongly or weakly), present on Ant I–II, dorsal head, Th II to Abd V and subcoxae outer side.

Mes ( Fig. 2). Finely ciliate and apically acuminate, present often on body laterally.

Mic ( Fig. 2). Heavily ciliate, apically acuminate and with similar sizes present on all body ( Fig. 3B).

S-chaetae. Ordinary sens ( Figs 2, 3B), smooth and apically rounded with similar sizes (type I), present on dorsal Th II – III (al), Abd I (acc.p6), Abd II – III (as, acc.p6), Abd IV (as, ps) and Abd V (as, acc.p4, acc.p5), and longer (type II), present on Abd IV; ms ( Figs 2, 3C), small, smooth and distally with rounded apex present on dorsal Th II, Abd I and III. Th II – Abd V with ms and sens formulae as 1, 0| 1, 0, 1, 0, 0, and 2, 2 | 1, 2, 2, +, 3, respectively .

Psp ( Figs 2, 4C, 10A, 11A, 17). Small, circular, smooth concavities with a narrow opening in the edges, always present centrally on Ant IV, 1+1 on Th II–Abd IV centrally, subcoxa I–III outer sides with 2, 2–4 and 2 respectively, dorsal manubrium with 3 proximal (1 unpaired) and manubrial plate with 2–3 psp ( Figs 10A, 11A, 18A–C, 19A, 26A–C, 27C, 33A–C, 34C, 40A–C, 41C, 46A–C, 47C, 52A–B, 53C, 58A–C, 65A–B, 70A–B).

Head. Antennae length variable, all segments with elongate sens, finger-shaped and s-blunt sens of different sizes and weakly to heavily ciliated chaetae ( Fig. 4); Ant IV weakly annulated ( Fig. 4C); Ant III distally typically with 2 apical sens and 3 guard sens ( Fig. 4D); Ant I with at least 2 smooth mic at the base ( Fig. 4F).

Eyes 8+8, with 4–6 interocular (IO) chaetae (q, v, s, p, r, t) ( Figs 5, 15D). Head dorsal macrochaetotaxy ( Fig. 5) with 12 series: ‘ An ’, ‘ A ’, ‘ M ’, ‘ S ’, ‘ Ps ’, ‘ Pa ’, ‘ Pi ’, ‘ Pm ’, ‘ Pmp ’, ‘ Pp ’, ‘ Ppe ’ and ‘ Pe ’ ( Fig. 15D); Clypeus with f and pf series of chaetae, f with a variable number, l1–2 chaetae generally apically acuminate (15C).

Four prelabral chaetae (pl1–pl2) with similar sizes, weakly ciliated or smooth, simple or distally bifurcated equally or unequally ( Figs 6A, 23C, 37C, 49D). Labral formula with 4 (a1–2), 5 (m0–2), 5 (p0–2) smooth chaetae, a1 not thicker than the others, p0–2 longer than the others, others subequal ( Fig. 43C). Four labral papillae (inner and outer) variable in shape and size. Labial palp with five main papillae (A–E) plus a hypostomal one (H), respectively with 0, 5, 0, 4, 4, 2 guard appendages ( Fig. 7B), papilla E with l.p. slightly striate and variable in shape or size ( Figs 7C, 31B, 38B, 56B); labium with five smooth proximal chaetae ( Figs 7A, 16C, 24C, 31D). Maxillary palp with t.a. and b.c. smooth; sublobal plate internally with bs1–3 smooth, plus 1 small smooth appendage distally ( Figs 7A, 31C). Basolateral and basomedian labial fields with chaetae a1–5 smooth, M1–2, R, E and L1–2 ciliated ( Figs 7A, 16C, 24C). Head ventrally with numerous ciliate chaetae of different sizes; postlabial G, X and H series present, and some chaetae surrounding the cephalic groove ( Figs 16D, 24D, 31E, 38C).

Dorsal chaetotaxy. All segments with primary and secondary chaetae in a, m and p transversal series, except Abd IV with longitudinal series (A–Fe) ( Fig. 17C). Always with numerous polymorphic chaetae (mac or mes present or absent) and sometimes with atypical or infrequent variations (eg. m5 and m5a on Th II) ( Figs 17A, 25A).

Thoracic morphology and chaetotaxy. Th II longer than Th III. Th II a series (excluding the anterior collar) posteriorly formed by some mac (e.g. a1p, a2a– a2e, a5p–a5i2) and specific to each species; m series with some polymorphic mac (m1i, m2i, m2ip, m2p, m4i, m4p), which are generally used in the diagnosis of Entomobrya species (e.g. Baquero et al. 2010; Jordana & Baquero 2010; Jordana & Greenslade 2020); p series with p1–3 extra secondary mac. Th III a series with a1–7 as mac, a1–2 and a7 present or absent; m series with m1 rarely present and m5i, m6–6p mac present or absent; p series with p1–6 mac, p1 and p2 (including secondary chaetae) rarely absent, p1i–1ip, p1p–1p2, p2a–2p, p3 and p6e polymorphic ( Figs 17A, 25A, 32A, 39A, 45A, 51A).

Abdominal chaetotaxy. Abd I–III with a series variable, as a2 and a3 polymorphic on Abd I–II; m series generally with 5 stable mac on Abd I (m2, m4, m4i, m4, m5), and 4 on Abd II (m3, m3e, m3ep, m5); Abd III devoid of m3 mac, except in E. bicyana sp. nov. ( Figs 17B, 25B, 32B, 39B, 45A, 51A, 57B, 64B, 69B). Abd IV with inner mac series (A–C) and outer (T–Fe), rarely with unpaired chaetae present centrally; inner region with two irregular rows of transverse mac, posteriorly with some clustered mac; outer region with a dense macrochaetotaxy, usually with extra mac; all series often with polymorphic mac ( Figs 17C, 25C, 32C, 39C, 45C, 57C, 64C, 69C). Entomobrya bicyana sp. nov. with a reduced number of macrochaetae, differing from other species patterns ( Fig. 51A–C). Abd IV number of sens (type I and II) and posterior mes specific to each species; with a, m, pa, p series, usually with two groups of 4 mac, inner (m2, m3, p1, p3) and outer (a5, m5, p4, p5), other extra mac species-specific ( Figs 17C, 25C, 32C, 39C, 45C, 51C).

Trunk appendages. Legs. Trochanteral organ with smooth spine-like chaetae apically pointed and of different sizes, organized in anterior, posterior, internal, apical, and distal series ( Fig. 18D). Femur I – III with ciliated chaetae. Tibiotarsus I – III inner side with a row of finely ciliate mac, distally with 1 “smooth” chaeta (discretly striated) on tibiotarsus III; outer side with 1 outer apically acuminate mac at the base, distally with 1 finely ciliated and apically capitate tenent hair ( Figs 8B–C). Pretarsus with one minute anterior and one posterior smooth chaeta ( Fig. 18E). Unguis inner side with 4 teeth, b.t. paired (anterior and posterior), 1 m. t. and 1 a.t. unpaired; outer side with multiple parallel lines with 3 teeth apically truncate, 2 paired large laterobasal teeth with linear striations and one unpaired minute proximal tooth slightly striated ( Fig. 8C). Unguiculus with 4 lamellae, 2 anterior (ai, ae) and 2 posterior (pi, pe) ( Figs 8C–D) .

Collophore. Anterior side with ciliated chaetae of different sizes and widely distributed on corpus, distally with elongated finely ciliate mac (with a variable number of these mac among species) ( Figs 9B, 19A, 27A). Posterior side with thin ciliated chaetae widely distributed distal half always with 1 elongated unpaired apically acuminate mac; distally with 1 smooth chaetae ( Fig. 9C). Lateral flap with some distal smooth chaetae and proximal ciliated chaetae, with a variable number on each species ( Figs 9A, 19A, 27A, 34A, 41A). Eversible sacs with an inner row (proximal to distal) with numerous papillae of different shapes ( Fig. 9B).

Tenaculum. Basal corpus with 1 chaeta weakly striated and a pair of lateral rami with 4 teeth ( Fig. 9D).

Genital plate. Papillate in males, with about 14 smooth circumgenital sickle-shaped chaetae and 3+3 small smooth eugenital chaetae ( Fig. 10A). Females with two pairs (superior and inferior) of small smooth chaetae, without other clear modifications ( Fig. 10B).

Furcula. Manubrium shorter or subequal to the dens; ventral side with heavily or slightly ciliated chaetae of different sizes, subapical and apical chaetae ciliated with different sizes and always present ( Fig. 19B); dorsal side densely covered by ciliated chaetae of different sizes, manubrial plate distally with ciliated chaetae of different sizes, inner chaetae generally as mac ( Fig. 11A). Dens proximally with 2 (bs1 and bs2) thick ciliate chaetae subequal to each other. Dens dorsally crenulated (distally variable among the species), with numerous ciliated chaetae of different sizes; sometimes distally with an inner and/or outer rows of robust modified chaetae, weakly ciliated and apically acuminate ( Figs 11A–B). Mucro bidentate, teeth finely striated, except for the outer side of the distal tooth, inner margin of distal tooth serrated; proximal spine enterily striated on the outer side, internally with a protruding ridge, posteriorly concave and anteriorly striated ( Fig. 11C).