Homidia apigmenta

Shi, Shi-Di, Pan, Zhi-Xiang & Zhang, Feng, 2010, A new species and a new record of the genus Homidia Börner, 1906 from East China (Collembola: Entomobryidae), Zootaxa 2351, pp. 29-38 : 30-34

Homidia apigmenta n sp.

Figs 1–22 , Table 1

Type material. Holotype, female on slide, CHINA: Fujian Province: Shaowu City, Shunchang Country, 22. x. 2008, collection number S 08102206, collected by Zhi-Xiang Pan & Xin Qi. Paratypes, 9 females and 2 males on slide and 15 in alcohol, same data as holotype. Four paratypes (2 on slide and 2 in alcohol) deposited in Nanjing University and others (9 on slide and 13 in alcohol) in School of Life Sciences, Taizhou University, China.

Description. Size. Maximum body length up to 3.7 mm.

Colour pattern. Ground colour pale in alcohol ( Figs. 1–2 ). Eye patches dark blue and with transverse band in front of eyes. Antennae pigmented and gradually darker towards tip. Lateral margin of Th. II–III and coxa slightly pigmented. No pigment on body, legs and furcula.

Head. Eyes 8+8; G and H smaller than others, and sometimes invisible under light microscope ( Fig. 3 ). Antenna 2.5–3.1 times as long as cephalic diagonal; antennal segment ratio as I:II:III:IV=1:1.3–1.7:1.3– 1.7:1.6–2.8. Basal Ant. I with 3 dorsal and 4 ventral spiny straight setae ( Fig. 4 ). Distal Ant. II with 3–4 rodlike sensory setae ( Fig. 5 ). Ant. III organ with 2 rod-like sensilla ( Fig. 6 ). Ant. IV apical bulb bilobed ( Fig. 7 ). Dorsal cephalic chaetotaxy (following Szeptycki 1973) with 3 antennal (A), 3 ocellar (O) and 5 sutural (S) macrochaetae ( Fig. 3 ). Labral papillae absent. Prelabral and labral setae as 4/5, 5, 4, all smooth. Maxillary outer lobe with 1 apical seta, 1 subapical seta and 3 sublobal hairs on sublobal plate; subapical seta subequal in length to and slightly thicker than apical one ( Fig. 8 ). Five papillae A–E on labial palp (following Fjellberg 1998) respectively with 0, 5, 0, 4, 4 guard setae; lateral process differentiated being thick as normal with tip not reaching apex of the same papilla ( Fig. 9 ). Setal formula of labial base usually as M, R, E, L1 and L2 (supplementary seta of M rarely present) (following Gisin 1964); seta E smooth and others ciliate; seta M slightly expanded; setae L1 and L2 strongly expanded and leaf-like; partial setae posterior to labium also strongly expanded ( Figs. 12 a and 12b).

Thorax. Th. II with 4 medio-medial (m1, m2, m 2i, m 2i 2), 3 medio-sublateral (m4, m 4i, m4p), 27–31 posterior setae and 3 s-chaetae; p 4i 2 sometimes absent; p6 as mesochaeta. Th. III with about 40 macrochaetae and 2 s-chaetae; macrochaeta p4 absent ( Fig. 10 ). Coxal macrochaetal formula as 3/4+1, 3/4+2 ( Fig. 11 ). Trochanteral organ with 33–43 smooth spiny setae ( Fig. 13 ). Inner differentiated tibiotarsal setae slightly ciliate, most distal smooth seta present on hind leg. Tenent hair clavate and slightly longer than inner edge of unguis. Unguis with 4 minute inner teeth and 2 lateral teeth. Unguiculus lanceolate with outer edge slightly serrate ( Fig. 14 ).

Abdomen. Abd. I with 10 (11) (a1–3, m2–4, m 2i, m 4i, m4p, a5; a1a sometimes absent) macrochaetae and 2 s-chaetae. Abd. II with 6 (a2, a3, m3, m3e, m3ea, m3ep) central, 1 (m5) lateral macrochaetae and 2 schaetae. Abd. III with 2 (a2, m3) central, 4 (am6, pm6, m7a, p6) lateral macrochaetae and 3 s-chaetae ( Fig. 15 ). Abd. IV with 6–9 macrochaetae on anterior part, arranged in irregular transverse row; posterior part with 4 (A6, Ae7, B4, B5) macrochaetae and 1 (B6) mesochaeta; Ae7 sometimes as mesochaeta ( Fig. 16 ). Abd. V with 3 s-chaetae; m3a and a 5i sometimes absent ( Fig. 17 ). Anterior face of ventral tube with many ciliate setae, including 4+4 as macrochaetae, line connecting proximal (Pr) and external-distal (Ed) (following Chen & Li 1997) macrochaetae oblique to median furrow ( Fig. 18 ); posterior face with 5–8 (mostly 5) subapical smooth and numerous ciliate setae ( Fig. 19 ); lateral flap with 6–7 smooth and 13–18 ciliate setae ( Fig. 18 ). Manubrial plaque with 3 pseudopores, 2 inner and 7–12 outer ciliate setae ( Fig. 20 ). Dentes with 18–39 spines; basal setae (following Szeptycki 1973) bs1 and bs2 spiny and multilaterally ciliate, bs1 slightly shorter than bs2; proximal-inner seta (pi) ciliate, apparently thinner, slender and longer than bs1 and bs2 ( Fig. 21 ). Mucro bidentate with subapical tooth obviously larger than apical one; basal spine short, with tip only reaching apex of subapical tooth ( Fig. 22 ). Tenaculum with 4+4 teeth and 1 large, multi-laterally ciliate basal seta. Genital plate papillate.

Ecology. In leaf litter of bamboo forest.

Etymology. Named after the unpigmented body.

Remarks. The new species is characterized by colour pattern with pigment absent on dorsal body tergites, leaf-like modified setae on ventral side of the head, presence of macrochaeta a1 on Abd. I, and absence of macrochaeta A4 and A5 on posterior side of Abd. IV.

It is most similar to H. polyseta in having expanded modified setae L1 and L2 and smooth E on ventral side of the head, claw structure, mucro, chaetotaxy on Abd. II and Abd. III, and macrochaetae on anterior face of ventral tube. It can be distinguished from the latter by absence of pigment on body, cephalic chaetotaxy, modified seta M on submentum, coxal macrochaetae formula, absence of A4 on Abd. IV, longer seta pi on dental base and fewer dental spines. It is also similar to H. latifolia , H. qimenensis , H. ziguiensis in having expanded modified setae ventrally on head, chaetotaxy of Abd. II–III, claw structure and mucro; however, it differs from them by colour pattern, having expanded modified M, L1 and L2 on labium, and in the macrochaeta A4 on Abd. IV. Differences between the new species and the other four similar species are listed in Table 1 .

Position of line connecting 4+4, oblique 3+3, oblique 3+3, oblique 3+3, oblique 4+4, subparellel

macrochaetae Pr and Ed to

median furrow of ventral tube

Distribution in China Fujian Hunan Zhejiang Anhui, Anhui Guangxi,

Jiangsu,

Zhejiang, Fujian

Figures

FIGURES 12. Homidia apigmenta n. sp. 12 a – 12 b, labium.

FIGURES 1 – 2. Homidia apigmenta n. sp. 1 – 2, colour pattern. 1, lateral view; 2, dorsal view.

FIGURES 3 – 11. Homidia apigmenta n. sp. 3, dorsal cephalic chaetotaxy; 4, basal Ant. I; 5, distal Ant. II; 6, Ant. III organ; 7, apical bulb on Ant. IV; 8, maxillary outer lobe; 9, labial palp; 10, dorsal thoracic chaetotaxy; 11, coxal macrochaetae (A, fore legs; B, mid legs; C, hind legs).

FIGURES 13 – 22. Homidia apigmenta n. sp. 13, trochanteral organ; 14, claw on hind leg; 15 – 17, dorsal abdominal chaetotaxy. 15, Abd. I – III; 16, Abd. IV; 17, Abd. V; 18 – 19, ventral tube. 18, anterior face and lateral flap; 19, posterior face; 20, manubrial plaque; 21, basal part of dens; 22, mucro.

Tables

TABLE 1. Differences between all Homidia species with modified expanded setae on ventral side of the head.

	H. apigmenta . n. sp.	H. polyseta	H. latifolia	H. qimenensis	H. ziguiensis
Labial basal seta M S Labial basal seta M	rarely present expanded	present normal	present normal	absent normal	present slightly expanded
Labial basal seta L1	expanded	expanded	normal	normal	slightly expanded
Labial basal seta L2	expanded	expanded	normal	normal	slightly expanded
Cephelic chaetotaxy	3A, 3O, 5S	4A, 3O,6S	3A, 3O, 5S	3A, 3O, 5S	3A, 3O, 6S
Macrochaeta A4 Abd. IV	absent	present	present	present	present
Dental spines	18–39	47–64	21–38	39–54	42–66
Dental basal seta pi	slender	spiny, thick	slender	spiny, thick	spiny, thick
Comparison of dental basal setae in length	pi> bs2> bs1	bs2> bs1> pi	pi> bs2> bs1	bs2> bs1> pi	pi> bs2> bs1