Collembola, Symphypleona, Sminthuridae): a New Species from Australia with Comments on the Genus and on the Sminthurinae
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insects Article The Rare Richardsitas Betsch (Collembola, Symphypleona, Sminthuridae): A New Species from Australia with Comments on the Genus and on the Sminthurinae Gleyce da S. Medeiros 1,* , Penelope Greenslade 2,3 and Bruno C. Bellini 1,* 1 Departamento de Botânica e Zoologia, Laboratório de Collembola, Centro de Biociências, Universidade Federal do Rio Grande do Norte—UFRN. BR 101, Lagoa Nova, Campus Universitário, Natal 59072-970, Brazil 2 School of Science, Psychology and Sports, Federation University, Ballarat, VIC 3353, Australia; [email protected] 3 Department of Biology, Australian National University, GPO Box, Canberra ACT 0200, Australia * Correspondence: [email protected] (G.d.S.M.); [email protected] (B.C.B.) Received: 26 June 2020; Accepted: 20 July 2020; Published: 11 August 2020 Abstract: Richardsitas Betsch is a small genus of Sminthurinae with only two species described so far, both from Madagascar. It resembles other Sminthurinae with long antennae, especially Temeritas Richards. Here we provide the first record of Richardsitas from Australia, Richardsitas subferoleum sp. nov., which is similar to R. najtae Betsch and R. griveaudi Betsch in males’ large abdomen chaetotaxy and presence of tenent-hairs on tibiotarsi II–III, but lacks mucronal chaeta and has 28 segments on the fourth antennal segment plus a unique pair of sensilla on the second. We also provide an updated genus diagnosis to Richardsitas, a key to its species, a discussion of the affinities of Temeritas and Richardsitas to other Sminthurinae, and an updated key to this subfamily. Keywords: chaetotaxy; Oceania; Sminthuroidea; survey; Temeritas-group 1. Introduction The family Sminthuridae Lubbock, 1862 [1] has about 260 nominal species in 32 genera and represents one of the most common and widespread groups of Symphypleona [2–4]. It comprises three subfamilies of which the Sminthurinae, Lubbock, 1862 is the largest, with about 180 species described in 12 extant and seven extinct genera [2,4–9]. The diagnosis of Sminthurinae was recently updated by Zeppelini et al. [9] and its main features are long antennae, mostly longer than the body; fourth antennal segment with well-marked subsegments; tibiotarsi with more than six chaetae on distal whorl; ungues without cavity; absence of neosminthuroid chaetae on the parafurcal area except in Keratosminthurus Zeppelini, 2020 in Zeppelini et al. 2020 [9]; dens ventrally usually with more than 9 chaetae [2,5,9]. The Sminthurinae fauna is poorly understood in Oceania and there are only four recorded species from Australia in two different genera: Sminthurus viridis (Linnæus, 1758) [10], Temeritas denisii (Womersley, 1934) [11], T. regalis (Womersley, 1939) [12]; T. isabellae Greenslade, 2013 [13,14]. Richardsitas Betsch, 1975 [15] is a small genus of Sminthurinae with only two described species, both from Madagascar: R. griveaudi Betsch, 1977 [16] and R. najtae Betsch, 1975 [15]. It is similar to Temeritas Richards, 1963 in Delamare Deboutteville and Massoud, 1963 [17], Galeriella Curˇci´cand´ Luˇci´c, 2007 in Curˇci´cet´ al. 2007 [18] and Keratosminthurus, as well as species with long antennae of Sminthurus Latreille, 1802 [19], Novokatianna Salmon, 1944 [20], Spatulosminthurus Betsch and Betsch-Pinot, 1984 [21] and Pararrhopalites Bonet and Tellez, 1947 [22]. Such taxa have several subsegments (mostly 18 or Insects 2020, 11, 519; doi:10.3390/insects11080519 www.mdpi.com/journal/insects Insects 2020, 11, 519 2 of 16 more) on Ant IV, a metatrochanteral spine (except for Sminthurus and Spatulosminthurus), and mainly share a similar dental chaetotaxy [2,5,9,18,20,22–24]. However, Richardsitas is unique in its strong sexual dimorphism regarding the dorsal chaetotaxy of the large abdomen of the males, combined with capitate tenent-hairs on second and third pairs of legs [5,15,16]. Among the Sminthurinae, Richardsitas appears most similar to Temeritas as noted by Betsch [5,15], and females of both genera can be only clearly distinguished by presence/absence of capitate tenent-hairs. Herein we describe in detail the first species of Richardsitas from Australia and update the generic diagnosis. We also provide a key to Richardsitas species and discuss its affinities with other Sminthurinae genera. Finally, based on our survey of the Sminthurinae, we provide an updated key to the extant genera. 2. Materials and Methods The specimens were preserved in ethanol, cleared in Nesbitt’s solution, and mounted in glass slides using Berlese’s medium. Morphological studies and raw drawings were made with a Leica DM750 microscope with an attached drawing tube. Photographs were taken with the same microscope, with a Leica MC170 HD camera using LAS V. 4.12 software. Final figures were improved and organized in plates using CorelDraw X8 software. Type series was deposited at the South Australian Museum, Adelaide, Australia, under the acronym of SAMA. The terminology used in descriptions follows Betsch and Waller [25] for head and large abdomen chaetotaxy and Betsch [26] for small abdomen chaetotaxy, using as a model the species in Medeiros and Bellini [24]; Fjellberg [27] for labial palp papillae and Cipola et al. [28] for labral chaetotaxy. The abbreviations and symbols used are: Abd—abdominal segment; Ant—antennal segment; Th—thoracic segment. Chaetae present or absent are marked with white arrows, unpaired chaetae on frontal head and trunk are marked with a ‘*’ on drawings, extra chaetae on head without clear homologies are circled. Head, trunk (thorax + abdomen), and furcal chaetotaxy are given by half body in the text description. The chaetal labels are marked in bold in the text. 3. Results 3.1. Taxonomic Summary and Genus Diagnosis Order Symphyleona Börner, 1901 [29] Superfamily Sminthuroidea Bretfeld, 1994 [30] Family Sminthuridae Lubbock, 1862 [1] Subfamily Sminthurinae Lubbock, 1862 [1] Genus Richardsitas Betsch, 1975 [15] Diagnosis. Specimens pigmented. Antennae longer than body length; Ant IV longer than Ant I–III combined, with 28–30 subsegments; Ant III apical organ sensory rods apart, in independent shallow invaginations. Eyes 8 + 8. Head frontal area with at least 3 pairs of spine-like chaetae; post antennal chaeta absent. Trochanter III with five normal chaetae plus one posterior spine. Tibiotarsi I–III with normal smooth or slightly serrated chaetae, tibial oval organs absent; capitate tenent-hairs present on tibiotarsi II–III; posterior and anterior pretarsal chaetae present. Ungues lanceolate without cavity or tunica, unguiculi with the apical filament. Large abdomen with anterior and posterior dorsal spines, with typical smooth or slightly serrated chaetae plus slender spines in females, and with 3–4 fields of peculiar short candle-shaped or spine-like chaetae in males. Bothriotrichia A–D present, A–C misaligned. Neosminthuroid chaetae absent on parafurcal area (furcal basis). Dens with 13 ventral chaetae, their formula as 1:1:2:2:2:2:3 from the basis to the apex. Mucro slender, with narrow apex, with both edges serrated. Mucronal chaeta present or absent (adapted from Betsch [5,15,16]). Type species. Richardsitas najtae Betsch, 1975 [15]. Insects 2020, 11, 519 3 of 16 3.2. Richardsitas subferoleum sp. Nov. Figures1–5, Table1. Insects 2020, 11, x 6 of 16 Figure 1. Richardsitas subferoleum sp. nov. head: (A) left Ant IV, arrow points to apical curved chaeta; Figure(B 1.) leftRichardsitas Ant I–III, arrow subferoleum on Ant II sp.points nov. to two head: modified (A) left apical Ant sensilla, IV, arrow arrow pointson Ant III to points apical to curved chaeta; (B) leftapical Ant organ I–III, of arrow Ant III; on(C) Antfrontal II head points chaetotaxy, to two circles modified = extra apicalchaetae sensilla,without clear arrow homologies, on Ant III points to apical*organ = unpaired of Ant chaetae, III; (whiteC) frontal arrows headpoint to chaetotaxy, chaetae present circles or absent;= extra (D) chaetaeventral head without chaetotaxy, clear homologies, arrows point to cuticular spines; (E) right maxillary outer lobe and sublobal plate; (F) labial palp * = unpaired chaetae, white arrows point to chaetae present or absent; (D) ventral head chaetotaxy, papillae (left side) and proximal chaetae (circles), lateral process in black; (G) prelabral and labral arrowschaetae; point (H to) left cuticular maxilla capitulum; spines; (EI) )right right and maxillary left apices of outer mandibles lobe (incisive and sublobal teeth). plate; (F) labial palp papillae (left side) and proximal chaetae (circles), lateral process in black; (G) prelabral and labral chaetae; (H) left maxilla capitulum; (I) right and left apices of mandibles (incisive teeth). Insects 2020, 11, 519 4 of 16 Insects 2020, 11, x 7 of 16 FigureFigure 2. Richardsitas2. Richardsitas subferoleum subferoleum sp. nov. nov. legs: legs: (A) ( Aleg) legI; (B I;) (legB) II; leg (C II;) leg (C )III; leg (D III;) foot (D )complex foot complex I; (E) I; (E) foot complex II; II; (F (F) )foot foot complex complex III. III. Insects 2020, 11, 519 5 of 16 Insects 2020, 11, x 8 of 16 FigureFigure 3. 3.Richardsitas Richardsitas subferoleum subferoleum sp.sp. nov.nov. large abdomen: (A (A) )male male,, squares squares highlight highlight fields fields of ofshort short candle-shapedcandle-shaped chaetae chaetae on on dorsum; dorsum; ((BB)) female.female. Insects 2020, 11, 519 6 of 16 Insects 2020, 11, x 9 of 16 FigureFigure 4. 4.Richardsitas Richardsitas subferoleum subferoleumsp. sp. nov.nov. smallsmall abdomen and and furca: furca: (A (A) )chaetotaxy chaetotaxy