Arrhopalites brevicornis, Godeiro & Zhang & Bellini, 2022

Godeiro, Nerivania Nunes, Zhang, Feng & Bellini, Bruno Cavalcante, 2022, A new species of Arrhopalites Boerner (Collembola, Symphypleona, Arrhopalitidae) from China, with a key to the Asian species of the caecus group, ZooKeys 1102, pp. 163-176 : 163

publication ID	https://dx.doi.org/10.3897/zookeys.1102.81247
publication LSID	lsid:zoobank.org:pub:858E5369-0684-4DE7-AE5C-5482472191BA
persistent identifier	https://treatment.plazi.org/id/FED6DB53-B746-424D-93B0-105DA1AFA930
taxon LSID	lsid:zoobank.org:act:FED6DB53-B746-424D-93B0-105DA1AFA930
treatment provided by	ZooKeys by Pensoft
scientific name	Arrhopalites brevicornis
status	sp. nov.

Treatment

Arrhopalites brevicornis sp. nov.

Figs 1 View Figure 1 , 2 View Figure 2 , 3 View Figure 3 , 4 View Figure 4

Type material.

Holotype on slide “SNHM00001”: female, Jilin Province, China, 44°33'N, 123°31'E, 2013, in soil samples from the Ecological Research Station for Grassland Farm, July 2013, Bing Zhang leg. Paratypes on slides: 9 females on slides, same data as holotype. Besides the type material, 78 specimens are kept in 98% ethanol at the SNHM, plus several paratype slides are kept at the laboratory of Entomology, NJAU, China.

Diagnosis.

Female. Antennae short, about 1.4 times the head length. Ant IV not subdivided and short, about twice or less the length of Ant III. Eyes 1+1. Clypeal area a-f lines with 7(+1)/7/5/4-5/5/6 chaetae respectively, plus 3 central chaetae with unclear homologies, frontal area A-C lines with 1/1/2(+1) short stout spines. Small abdomen, dorsal anal valve with 2 cuticular spines per side and 4 sword-shaped smooth chaetae (ms1, mps1-3), ventral anal valves with 2 cuticular spines each and 3 sword-shaped smooth chaetae (mi3, mpi1-2), subanal appendage long, similar in length to mi3, mpi1-2, with a spatulated and apically serrated apex. Manubrium with 5 chaetae on each side, dens ventral formula from the apex to the basis as 3,2,1,1,1, dorsally with 16 chaetae. Mucro with both edges serrated, apically swollen. Ungues I slender, III broad, all with an underdeveloped tunica, unguiculus III with 2 inner teeth.

Description.

Female. Body (head + trunk) length of type series (females, N = 4) ranging between 0.71 and 0.81 mm, average 0.74 mm, holotype with 0.75 mm. Habitus as in Fig. 1 View Figure 1 . Specimens pale yellowish with brownish spots of pigment on frontal and dorsal head and dorso-lateral large abdomen. Body chaetae smooth and acuminate, with the exception of the subanal appendage.

Head (Figs 1 View Figure 1 , 2 View Figure 2 ). Antennae shorter than the body, with 0.32 mm in the holotype (Fig. 1 View Figure 1 ), ratio antennae: head length of the holotype 1.3:1, type series average 1.4:1. Holotype antennal segments ratio of Ant I:II:III:IV as 1:1.6:2.3:4.3, and of type series (N = 4) as 1:1.3-2.7:2.1-3.3:3.8-6.7. Ant IV short and stout, about twice or less the size of Ant III (in holotype, ratio Ant III:IV = 1:1.87), without subsegments, with about 87 regular chaetae of different sizes distributed in apparently 13 whorls (Fig. 2A View Figure 2 ). Ant III slightly swollen with 17 chaetae, Ape, Ae, Ap, Ai, Aa, Api, and Aai present, Api slightly reduced, Aai as the accessory microsensillum, sense rods not swollen inside separate invaginations (Fig. 2B View Figure 2 ). Ant II with 13 regular chaetae, Ant I with 7, the two more apical reduced (Fig. 2C View Figure 2 ). Eyes 1+1, head length (eyes to mouth) of holotype 0.25 mm. Clypeal area a-f lines with 7(+1)/7/5/4-5/5/6 chaetae respectively, plus 3 central chaetae of unclear homologies; interantennal area α and β lines with 2/1(+1) short chaetae respectively, plus 2+2 small oval organs (pseudopores) and 1+1 large circles lacking tegument granules near the lateral chaetae on α line; frontal area A-C lines with 1/1/2(+1) short stout spines, D line with 2 elongate thinner erect chaetae (Fig. 2D View Figure 2 ). Ventral groove with 2 surrounding chaetae from lines a and b, labial basomedian field with 4, basolateral field with 5 chaetae (Fig. 2E View Figure 2 ). Labial papilla E lateral finger-shaped, not reaching the papilla apex, other labial structures unclear. Maxillary outer lobe apical chaeta longer than the basal one, sublobal plate with three sublobal hairs (Fig. 2F View Figure 2 ). Distal margin of the clypeus with 3 prelabral chaetae, labral chaetotaxy with 2(+1) p, 2(+1) m and 2 a chaetae, all subequal (Fig. 2G View Figure 2 ).

Trunk (Fig. 3A, B View Figure 3 ). Trunk length of holotype 0.5 mm. Large abdomen: thorax continuous with abdomen, without any constrictions. Th II with 1 a and 3 m chaetae; Th III with 1 a and 3 m chaetae; Abd I with 5 a, 4 m and 1 p chaetae, respectively. Three chaetae (1-3) on the upper side of bothriotrichum A, plus accessory a1 nearby its alveolus; b1 accessory chaeta between B and C bothriotricha, c2 just under C, c1 absent; bothriotricha A-C misaligned, with B bothriotrichum closer to C than A; dorso-posterior longitudinal series dI-1, dII-1, dIII-1 with 5-7, 9-10 and 6-8 chaetae, respectively; two rows with 3 chaetae each between C and D bothriotricha; D with 4 surrounding chaetae posteriorly; parafurcal area (furcula basis) with 8 regular chaetae; ventral complex with 1 chaeta (Fig. 3A View Figure 3 ). Small abdomen of the female: dorsal anal valve with as2-4, ms1-5?, mps1-3, and ps1-2 chaetae, ms1 and mps1-3 sword-shaped and smooth, 2 cuticular spines surrounding mps2; ventral anal valves each with ai1-6, ami1-2, mi1-5, mpi1-2, and pi1-3 chaetae, mi3 and mpi1-2 sword-shaped and smooth, mi5 as the subanal appendage long (similar in length to mi3, mpi1-2) with a spatulated and apically serrated apex (sometimes one of the lateral edges is also distally serrated), curved toward the genital opening, 2 cuticular spines surrounding mpi2 (Fig. 3B View Figure 3 ). Genital plate of the female unclear.

Abdominal appendages (Fig. 3C-F View Figure 3 ) Collophore with 1 distal chaeta on each side, with a pair of a little wrinkled, almost smooth, sacs. Tenaculum with 3 teeth on each ramus plus the basal tubercle, with a single unpaired apical chaeta. Furcal size length in holotype: manubrium = 75 µm; dens = 113 µm; and mucro = 75 µm (ratio 1:1.5:1). Manubrium with 5 dorsal chaetae on each side, the most proximal thinner than the others (Fig. 3C View Figure 3 ); dens ventral (or anterior) formula from the apex to the basis as 3,2,1,1,1, all chaetae enlarged except for the most proximal one, (Fig. 3D View Figure 3 ); dens dorsally (or posteriorly) with 16 chaetae, 7 of them on the lateral edges of the more distal region more robust, almost spine-like (Fig. 3E View Figure 3 ). Mucro apically swollen with both edges serrated from the basis until almost the apex (Fig. 3F View Figure 3 ).

Legs. (Figs 3A View Figure 3 , 4 View Figure 4 ) Epicoxae, subcoxae and coxae I-III with 1,0,1/1,1,4/1,1,4 chaetae, respectively, coxae II-III with 1 long and 1 tiny chaeta each (Fig. 3A View Figure 3 ). Trochanters I-III with 4 chaetae each, II-III with 1 chaeta each modified as an anterior trochanteral organ (Fig. 4A-C View Figure 4 ). Femurs I-III with 13/13/14 chaetae respectively, of which 1/1/3 as reduced chaetae (Fig. 4A-C View Figure 4 ). Tibiotarsi without oval organs, tibiotarsus I region F with 3 chaetae (FPae, FPe, and FPpe), whorls I-V with 9,8,8,8,9 chaetae respectively, whorl I without clearly modified chaetae except for a larger dorsal one, whorl V with 2 ventro-distal chaetae (Fig. 4D View Figure 4 ). Tibiotarsus II region F with 3 chaetae (FPae, FPe, and FPpe), whorls I-V with 9,8,8,8,7 chaetae respectively, whorl I without clearly modified chaetae except for a slightly larger dorsal one, whorl V with 1 ventro-distal chaeta (Fig. 4E View Figure 4 ). Tibiotarsus III region F with 4 chaetae (FPae, FPe, FPpe, and FSa), whorls I-V with 9,8,8,8,7 chaetae respectively, whorl I without clearly modified chaetae except for a slightly larger dorsal one, whorl V with 1 ventro-distal chaeta (Fig. 4F View Figure 4 ). Foot complexes I-III with 2 pretarsal chaetae each, 1 anterior and 1 posterior; ungues (claws) without cavity or pseudonychia, but with an underdeveloped tunica covering about 2/3 up to 3/4 of the dorsal ungues, lateral lamellae apparently lacking teeth, each unguis with one internal tooth; unguis I slender, III broad (Fig. 4D-F View Figure 4 ). Unguiculi (empodia) never surpassing the ungues, unguiculus I almost reaching the apex of unguis I, unguiculi II-III clearly shorter; unguiculi I-II with one proximal internal tooth each, unguiculus III with 2 more distal teeth (Fig. 4D-F View Figure 4 ).

Male. Not found, species possibly parthenogenetic.

Etymology.

The new species was named after its short antenna (from Latin brevi - = short; cornis = “horns”, antennae).

Distribution and habitat.

The new species was collected and only recorded in Jilin Province, Changling County, at the Ecological Research Station for Grassland Farm (ERSGF). This region is characterized by a semi-arid continental monsoon climate, with cold, dry winters and warm, rainy summers. Annual mean temperature in the region ranges from 4.68 to 6.48 °C, and annual precipitation is 280 to 400 mm with about 70% falling in the June-August period (Changling County Climate Station, Jilin Province). Changling County is located at a transitional zone of cropping and grazing, with high economical potential. However, drastic environmental disturbances are happening in this region, like sand and dust storms, emergence of saline-alkali soils, and land over-utilization.

Remarks.

Arrhopalites brevicornis sp. nov. belongs to the A. caecus (Tullberg, 1871) group of species sensu Vargovitsh (2013), according to its ventral (or anterior) dental chaetotaxy (3, 2, 1, 1, 1). Currently, there are ten other Asian species of the genus which belong to this group: A. antrobius Yosii, 1954, A. abchasicus Vargovitsh, 2013, A. caecus , A. coreanus Park & Kang, 2007, A. gul Yosii, 1966, A. macronyx Vargovitsh, 2012, A. minor Park & Kang, 2007, A. minutus Yosii, 1970, A. potapovi Vargovitsh, 2015 and A. pukouensis , ( Bellinger et al. 1996-2022; Vargovitsh 2012, 2013, 2015). Arrhopalites brevicornis sp. nov. can be distinguished from all of them especially by the unguiculus III with 2 internal teeth (0-1 in all other species). Also, the combination of antennae less than 2 times the size of the head, Ant IV without annulations, 1+1 eyes, dorsal head with 9 spines, 2+2 regular spines per side on the anal valves, circumanal chaetae without basal serrations, subanal appendage long and apically serrated, similar in length to mi3, mpi1-2, manubrium with 5+5 and dorsal dens with 16 chaetae is unique among the Asian species of the Arrhopalites caecus group (see Table 1 View Table 1 ).

Concerning the species recorded from localities closer to Jilin Province, China, the South Korean A. coreanus , A. gul and A. minor share a similar color pattern, number of eyes, the presence of dorsal spines on head and number of dorsal dens chaetae with the new species. However the later differs from them by: the absence of Ant IV annulations (7 of A. gul ); antennae less than 2 times the size of the head (at least two times in A. coreanus and A. gul ); all ungues tunicate (without tunica on A. gul ); female’s subanal appendage apically serrated (pointed in A. coreanus and A. minor , and blunt in A. gul ); dorsal anal valve chaeta ms1 not forked (forked in A. coreanus ); circumanal chaetae without basal serrations (with in A. gul ) and manubrium with 5+5 chaetae (4+4 in A. gul , 9+9 in A. minor ).

The only other species of the Arrhopalites caecus group registered from China is A. pukouensis , from Nanjing, Jiangsu District, approximately 1800 km distant from the type location of the new species. Both species are vastly different as A. pukouensis is unpigmented (vs. pigmented), has no eyes and dorsal head spines (vs. 1+1 eyes and 9 spines, respectively), its ungues are devoid of tunica (vs. present); its female’s anal valves have no cuticular spines and their subanal appendage is short (vs. 2+2 spines per side and the subanal appendage is long, respectively) and its dorsal dens shows 15 chaetae (vs. 16 in the new species). A detailed comparison of the morphology and the known distribution of all the cited species is presented in Table 1 View Table 1 . We also provide a key of all Asian species of Arrhopalites caecus group below.