Sinhomidia uniseta, Pan, Zhi-Xiang, Si, Chen-Chong & Zhang, Shu-Sheng, 2019

Pan, Zhi-Xiang, Si, Chen-Chong & Zhang, Shu-Sheng, 2019, Close relationship between the genera Sinhomidia and Homidia (Collembola, Entomobryidae) revealed by adult and first instar characters, with description of a new Sinhomidia species, ZooKeys 872, pp. 41-55 : 41

Sinhomidia uniseta sp. nov. Figs 1-9 , 10-20 , 21-24 , 25-32 , 33-42 , 43-45

Description

(adult and subadult). Size. Body length up to 2.51 mm. Scales. Scales pointed and coarsely striated, present on dorsal side of head, thorax and abdomen ( Figs 6 , 7 ), with fewer scales present on antennae and legs. Ventral side of manubrium with longer and narrower scales than those of dorsal side of body ( Fig. 8 ). Colour pattern. Ground colour whitish in ethanol. Eye patches dark blue. Antennae with dark pigmentation, gradually darker from Ant. I to Ant. IV. A dark band between basal antennae. Lateral and anterior margin of Th. II, posterior half of Abd. II, whole Abd. III, posterior Abd. IV and femurs of the hind leg pigmented ( Figs 1-3 ). Ventral side of body and VT without pigment ( Fig. 3 ). Subadults with the same colour pattern as adults, but Th. II laterally and Abd. IV posteriorly lighter ( Fig. 4 ). Head. Eyes 8+8, G and H smaller than others and always difficult to observe using a light microscope; three chaetae (p, r, and t) within eye patches, with p largest ( Fig. 10 ). Antenna 2.10-2.45 times as long as cephalic diagonal; antennal segments ratio as I:II:III:IV = 1:1.48-1.91: 1.28 –1.56:2.51– 3.34. Ant. I basally with 3 dorsal and 4 ventral smooth mic ( Fig. 11 ). Ant. II with 5 basal smooth mic ( Fig. 12 ), and 1 longer (rarely 3) and 1 shorter rod-like distal S-chaetae ( Fig. 13 ). Ant. III organ with 2 rod-like and 3 short guard S-chaetae ( Fig. 14 ). Bulb on apical Ant. IV bilobed ( Fig. 15 ). Prelabral and labral chaetae as 4/5, 5, 4, all smooth; labral papillae absent ( Fig. 16 ). Clypeus with 15 mac in four lines, arranged as 3, 5, 4, 3 ( Fig. 17 ). Cephalic chaetotaxy on dorsal side with 3 antennal (A), 3 ocellar (O) and 5 sutural (S) mac, Gr. II with 3 mac ( Fig. 10 ). Chaetae on labium basis as MRel1L2, with e and l1 smooth; postlabial chaetae not expanded ( Fig. 18 ). Five papillae A–E on labial palp with 0, 5, 0, 4, 3 guard chaetae, respectively; lateral process (l.p.) normal, with tip reaching apex of papilla E; hypostoma with 2 guard chaetae; proximal chaetae 5 ( Fig. 19 ). Maxillary outer lobe with 1 apical chaeta, 1 subapical chaeta and 3 sublobal hairs on sublobal plate, subapical chaeta slightly larger than apical one ( Fig. 20 ). Thorax. Complete body sens as 2, 2/1, 2, 2, 33, 3, ms as 1, 0/1, 0, 1, 0, 0. Th. II with 4 medio-medial (m1, m2, m2i and m2i2), 3 medio-sublateral (m4, m4i and m4p) mac and 3 S-chaetae (ms antero-internal to sens); posterior with 17-19 mac; p6 as mic. Th. III with 17-19 mac and 2 sens; p5, p6 and m6 as mac, p4 as mic ( Fig. 21 ). Coxal macrochaetal formula as 3 (1 pseudopore)/4+1, 3 (3 pseudopores)/ 4+2 (pseudopore(s) unclear) mac ( Fig. 22 ). Trochanteral organ with 24-34 smooth chaetae, 5-6 in ventral and 3-4 in posterior line ( Fig. 23 ). Inner tibiotarsus with slightly ciliated chaetae. Tenent hairs clavate, slightly shorter than inner edge of unguis in length. Unguis with 3 inner and 2 lateral teeth, tooth on outer edge unclear. Unguiculus lanceolate with outer edge slightly serrate and the most basal tooth larger ( Fig. 24 ). Abdomen. Abd. IV 11-15 times longer than Abd. III along the dorsal axis. Abd. I with 3 mac (m2-4) and 2 S-chaetae (ms antero-external to sens). Abd. II with 5 central (a2, m3, m3e, m3ea and m3ep) and 1 lateral (m5) mac. Abd. III with 1 central (m3) and 4 lateral (am6, pm6, p6 and m7) mac, 2 sens and 1 ms. Abd. IV with 31 elongated and 2 normal length sens, and 10-14 mac arranged in anterior eyebrow-like line; postero-central area with 5 (7) mac (A4, A6, B4-6; Ae6 and Ae7 sometimes present). Abd. V with 3 sens, the middle one posterior to m3, the lateral one between chaetae a5 and m5 but shifted from anterior to posterior of a5 among the examined specimens; a1, a3, m3, m5, a5, m5, and a6 as mac, m3a sometimes as mac ( Fig. 25 ). Anterior face of VT with many ciliated chaetae, 3+3 of them as mac, in a line connecting proximal (Pr) and external-distal (Ed) mac obliquely to median furrow ( Fig. 26 ); lateral flap with 6-9 smooth and 10-11 ciliated chaetae on each side ( Fig. 27 ); apical smooth chaetae on posterior face variable, five of examined specimens have 5 (2+1+2), one has 7, and another one has 9 ( Fig. 28 ). Tenaculum with 4+4 teeth and 1 large, multi-laterally basally ciliated chaeta ( Fig. 29 ). Manubrial plaque with 3 pseudopores and 8-10 ciliated chaetae ( Fig. 30 ). Dens with 31-39 inner spines, basal chaetae (bs) spiny and multi-laterally ciliate, bs1 shorter than bs2, the morphology of chaeta pi unclear ( Figs 9 , 31 ). Mucro bidentate with subapical tooth larger than apical one; basal spine short, with tip reaching subapical tooth; distal smooth part of dens slightly shorter than mucro ( Fig. 32 ).

Description of the first instar larva.

Size. Body length up to 0.79 mm. Colour pattern. Ground colour whitish, eye patches dark, antennae and femurs of hind legs with weak pigments, posterior half of Abd. II and whole Abd. III pigmented. The colour pattern is similar to that of adults, but paler overall ( Fig. 5 ). Body. Body without scales. Complete tergal sens as 2, 2/1, 2, 2, 33, 3, ms as 1, 0/1, 0, 1, 0, 0. Cephalic chaetotaxy on dorsal side with 2 antennal (A), 2 ocellar (O) and 3 sutural (S) mac; eyes 8+8, eye patches with 3 chaetae (p, r, and t; p largest) ( Fig. 33 ). Labium with 3 proximal chaetae, 4 chaetae (M, e, a1 and a2) in basomedial field and 5 chaetae (a3-a5, l1 and L2) in basolateral field, chaetae M and L2 ciliate, and others smooth; posterior area of labium with 9 ciliated mac ( Fig. 38 ). Th. II with 7 anterior (a1-7), 6 median (m1-2, m4-7), and 6 posterior (p1-6) primary chaetae arranged in 3 rows; chaetae a7, m2, m5, m7 and p4-6 as mic, others as mac, and with 3 S-chaetae (ms antero-internal to sens). Th. III with 7 anterior (a1-7), 5 median (m1, m4-7), and 6 posterior (p1-6) primary chaetae arranged in 3 rows, and 2 S-chaetae; chaetae a7, m1, m4, m7, and p4-6 as mic, others as mac. Abd. I with 5 anterior (a1-3, a5-6), 5 median (m2-6), and 2 posterior (p5-6) primary chaetae arranged in 3 rows and 2 S-chaetae (ms antero-external to sens); chaetae m2-m4 as mac, others as mic. Abd. II with 6 anterior (a1-3, a5-7), 6 median (m2-7), and 4 posterior(p4-7) primary chaetae arranged in 3 rows, an additional chaeta external to p7 and 2 S-chaetae; chaetae a2, m3 and m5 as mac, a5 and m2 as bothriotricha, others as mic. Abd. III with 6 anterior (a1-3, a5-7), 7 median (m2-5, am6, pm6, m7), and 4 posterior (p4-7) primary chaetae arranged in 3 rows, 4 additional chaetae in lateral region, and 3 S-chaetae (1 ms and 2 sens); chaeta m3, am6 and pm6 as mac, m2, a5 and m5 as bothriotricha, others as mic ( Fig. 34 ). Abd. IV with 5 (A1-4, A6), 6 (B1-6), 4 (C1-4), 7 (T1-7), 3 (D1-3), 3 (E1-3), and 3 (F1-3) primary ciliated chaetae arranged in 7 longitudinal lines, an additional ciliated chaeta between B1 and B2 (shown by arrow in Fig. 35 ), and 31 elongated and 2 normal sens; T2 and T4 as bothriotricha. Abd. V with 13 primary chaetae (m2, m3 and m5 as mac; a1, a3, a5, a6, p1, p3, p4, p5, ap6 and pp6 as mic) and 3 sens, the median sens posterior to m3. Abd. VI with 16 ciliated chaetae on one side and 2 along the median axis ( Fig. 35 ). Appendages. Ant. I with 11 ciliated chaetae arranged in one ring and 1 basal smooth chaeta. Ant. II with 26 ciliated chaetae, arranged in 3 rings (8/8/9), basis without smooth spiny chaetae. Ant. III with 38 ciliated chaetae arranged in 4 rings (from basis to apex of Ant. III as 11/12/13/2) and 5 S-chaetae (Ant. III organ). Ant. IV with many S-chaetae (more than two types) and ciliated chaetae, apical bulb bilobed ( Fig. 37 ). Ventral tube with 2 smooth chaetae on the posterior face and on each lateral flap anterior face without chaetae ( Fig. 39 ). Manubrium with 42 ciliated chaetae, dens with numerous ciliated chaetae, without inner dental spines; chaetae bs2 longer than bs1, pi ciliated and similar in length to that of other ciliated chaetae; mucro with subapical tooth larger than apical one, basal spine absent ( Fig. 41 ). Tenaculum with 4+4 teeth and without chaetae ( Fig. 42 ). Four segments of fore, middle and hind leg with numerous chaetae, coxae with 1, 1, 1 chaetae, pseudopore unclear; trochanters with 6 (2 smooth), 6 (2 smooth), 5 (1 smooth and 1 spine like) chaetae; femurs with 13 (1 smooth), 17 (2 smooth), 17 (at least 1 smooth) ciliated chaetae; tibiotarsus with 39 (10/8/8/8/4 ciliated and 1 tenent hair), 41 (10/8/8/8/6 ciliated and 1 tenent hair), 48 (10/8/8/8/8/4, 1 tenent hair and 1 inner smooth chaetae) ciliated chaetae ( Figs 43-45 ).

Ecology.

Found in leaf litter of Calamus thysanolepis .

Holotype.

1♀ on slide, China, Guangdong Province, Guangzhou city, Tianhe District, Longdong reservoir, 23°14.134'N, 113°23.94'E, altitude 127 ± 5 m, sample number 4661, collected by Z-X PAN and S-S ZHANG, 24-III-2018. Paratypes. 4♀1♂adults, 1 subadult and 1 first instar larva on slides and 3 adults in ethanol, same data as holotype. All types were deposited at the School of Life Sciences, Taizhou University.

Etymology.

Specific epithet refers to the single chaeta M on labial basis (uni + seta).

Remarks.

Sinhomidia uniseta sp. nov. can be easily distinguished from the other two species of the genus by the dark pigment present on the lateral and anterior margins of Th. II, posterior margin of Abd. II and whole Abd. III, labial single M chaeta, three mac and ms external to sens on dorsal side of Abd. I, 5 (7) mac in postero-median area of Abd. IV, middle sens posterior to m3 on Abd. V, and three teeth on inner side of unguis. Detailed differences between the three species of Sinhomidia are listed in Table 1.

Figures

Figures 1 - 9. Sinhomidia uniseta sp. nov. 1 - 5 Habitus: 1 dorsal view of adult 2 lateral view of adult 3 ventral view of adult 4 dorsal view of subadult 5 lateral view of 1 st instar larva 6 postero-median scales on Abd. IV 7 scales and bothriotrichal complex on Abd. III 8 scales on manubrium 9 dental spines.

Figures 10 - 20. Sinhomidia uniseta sp. nov. 10 Cephalic chaetotaxy on dorsal side 11 basis of Ant. I 12 basis of Ant. II 13 distal part of Ant. II 14 Ant. III organ 15 distal part of Ant. IV 16 labrum 17 clypeal chaetotaxy 18 labium 19 labial palp 20 maxillary outer lobe 10 - 16 dorsal view 17 - 19 ventral view 20 lateral view. Scale bars: 50 μm.

Figures 21 - 24. Sinhomidia uniseta sp. nov. 21 Chaetotaxy of Th. II-III tergites 22 Coxae (A fore leg B middle leg C hind leg) 23 Trochanteral organ 24 Distal part of tibiotarsus and claw of hind leg 21, 24 dorsal view 22, 23 lateral view. Scale bars: 50 μm.

Figures 25 - 32. Sinhomidia uniseta sp. nov. 25 Dorsal chaetotaxy of Abd. I-Abd. V tergites 26 anterior face of ventral tube 27 lateral flap of ventral tube 28 posterior face of ventral tube 29 tenaculum 30 manubrial plaque 31 basal part of dens 32 distal part of dens and mucro 25, 26, 31, 32 dorsal view 28 - 30 ventral view 27 lateral view. Scale bars: 50 μm.

Figures 33 - 42. The first instar larvae of Sinhomidia uniseta sp. nov. 33 Dorsal cephalic chaetotaxy 34 chaetotaxy of Th. II-Abd. III tergites 35 chaetotaxy of Abd. IV-VI tergites 36 chaetotaxy of Ant. I-III 37 distal part of Ant. IV 38 labium 39 ventral tube 40 manubrium 41 dens 42 tenaculum 33 - 37, 39 - 42 dorsal view 38 ventral view. Scale bars: 50 μm.

Figures 43 - 45. Left legs of the first instar of Sinhomidia uniseta sp. nov. 43 - 45 Anterior view of fore leg (43), mid leg (44) and hind leg (45). Scale bars: 50 μm.