Homidia chroma, Pan & Yang, 2019

Pan, Zhi-Xiang & Yang, Wan-Qin, 2019, Reports of two peculiar pigmented new species of genus Homidia (Collembola: Entomobyridae) from Southern China, with description of subadults chaetotaxy, Zootaxa 4671 (3), pp. 369-380 : 370-373

Homidia chroma sp. nov.

Figs 1–32 , table 1

Type material. Holotype: female on slide, China, Guangdong Province, Guangzhou City, Tianhe District, Longdong Reservoir , 23.235566N 113.399017E, alt. 127± 5 m, sample number 4661, 25.III.2018, collected by Z-X Pan and S-S Zhang.

Paratypes. Six adults (male and five females) and two first instar larvae on slide, four in ethanol. Same date as holotype. All types deposited in the School of Life Sciences, Taizhou University ( TZU) .

Etymology. Named after chrome yellow pigment on lateral terga.

Description. Adults. Size: body lengths up to 2.64 mm. Colour pattern. Ground colour pale white. Eye patches dark blue. Ant. I–III with distal dark rings and narrower on Ant. I; whole Ant. IV slight pigment. Lateral Th. II–Abd. III, postero-lateral part of Abd. IV with chrome yellow to slightly brown pigment. Medial and posterior margin of Abd. IV with narrow transverse chrome to brown pigmented bands, and medial one interrupted in median. Coxae and anterior face of VT with slight pigment. Ventral side unpigmented ( Figs 1–3 ).

Head. Eyes 8+8, G and H smaller than others; eye patches with three chaetae ( Fig. 10 ). Antennal length 1.70– 1.93 times as long as head. Antennal segment ratio as I: II: III: IV=1: 1.48–1.86: 1.18–1.45: 2.17–2.52. Ant. I with three dorsal five ventral basal smooth mic ( Fig. 5 ). Ant. II with five basal smooth mic ( Fig. 6 ), two distal rodlike S-chaetae ( Fig. 7 ). Ant. III organ with two rod-like and three short guard S-chaetae ( Fig. 8 ). Apical bulb of Ant. IV bilobed ( Fig. 9 ). Dorsal cephalic chaetotaxy with three antennal (A), three ocellar (O) and five sutural (S) mac, Gr. II with five mac ( Fig. 10 ). Prelabral and labral chaetae as 4/5, 5, 4, all smooth. Chaetotaxic formula of labial base as MRel 1 L 2, e and l 1 smooth and others ciliate; postlabial chaetae not expanded with G 1–4, H 1–4, X, X 3 ciliate, and the morphology of X 2 unclear ( Fig. 11 ). Five papillae A–E on labial palp with 0, 5, 0, 4, 4 guard chaetae, respectively; lateral process (l.p.) thin with tip reaching apex of papilla E; hypostoma with two guard chaetae; proximal chaetae five ( Fig. 12 ). Maxillary outer lobe with one apical, one subapical chaetae and three sublobal hairs on sublobal plate, subapical chaeta longer than apical one ( Fig. 13 ).

Thorax. Complete body sens as 2, 2/1, 2, 2, (68), 3, ms as 1, 0/1, 0, 1, 0, 0. Th. II with four centro-medial mac (m1, m2, m 2i and m 2i 2), three centro-sublateral mac (m4, m 4i and m4p) and three S-chaetae (ms antero-internal to sens); posterior part with 27–28 mac; p4, p 4i, p5 and p6 as mac. Th. III with 36–43 mac and two sens; a5 without secondary chaetae; p5 and p6 as mac, p4 as mic ( Fig. 19 ). Coxal macrochaetal formula as 3 (one pseudopore) / 4+1, 3 (three pseudopores) / 4+2 (pseudopore unclear) ( Figs 14–16 ). Trochanteral organ with 25–41 smooth chaetae ( Fig. 17 ). Inner tibiotarsus with 2–3 lines of slightly ciliate chaetae. Tenent hair clavate, subequal to inner edge of unguis in length. Unguis with three inner, two lateral and one outer teeth. Unguiculus lanceolate with outer edge smooth ( Fig. 18 ).

Abdomen. Abd. IV length 7.18–8.01 times as long as Abd. III. Abd. I with 11 mac (a1–3, a 1i, m2–4, m 2i, m 4i, m4p and a5) and two S-chaetae (ms antero-external to sens). Abd. II with six central mac (a2, a3, m3, m3e, m3ea and m3ep) and one lateral mac (m5). Abd. III with two central mac (a2 and m3) and four lateral mac (am6, pm6, p6 and m7a) ( Fig. 19 ). Abd. IV with 66 elongate and two normal length sens (with sens present anterior to “eyebrow”); “eyebrow” with 9–12 mac; posteriorly central with six mac (A4, A6, Ae7, B4–5) ( Fig. 20 ). Abd. V with three sens, middle one postero-external to m3; a1, a3, a 5i, m3a, m5a and a6a as mac ( Fig. 20 ). Anterior face of VT with many ciliate chaetae, 3+3 of them as mac, line connecting proximal (Pr) and external-distal (Ed) mac parallel to median furrow ( Fig. 21 ); posterior face with five (2+1+2) apical smooth chaetae; lateral flap with 5–7 smooth and 11–12 ciliate chaetae on each side ( Figs 22–23 ). Tenaculum with 4+4 teeth and one large, multi-laterally basal ciliate chaeta ( Fig. 24 ). Manubrial plaque with three pseudopores and 9–12 ciliate chaetae ( Fig. 25 ). Dens with 44–57 spines ( Fig. 26 ). Mucro bidentate with subapical tooth larger than apical one; basal spine short, with tip reaching subapical tooth; distal smooth part of dens shorter than mucro in length ( Fig. 27 ).

First instar larvae. Size. Body length up to 0.7 mm. Colour pattern. Body without pigment except eye patches dark blue ( Fig. 4 ).

Chaetotaxy. Chaetotaxic formula of labial base as Mel 1 L 2 chaetae; proximal chaetae three ( Fig. 30 ). Th. II with 20 primary chaetae arranged in three rows (7/7/6), and three S-chaetae (ms antero-internal to sens); a7, m2, m5, m7, p4 and p6 as mic, others as mac. Th. III with 18 primary chaetae arranged in three rows (7/5/6), and two S-chaetae; a7, m1, m4, m5, m7, p4–6 as mic, other as mac. Abd. I with 12 primary chaetae and two S-chaetae (ms antero-external to sens); m2–4 as mac, others as mic. Abd. II with 16 primary chaetae, m3 and m5 as mac, others as mic, two trichobothria (m2 and a5), and two S-chaetae. Abd. III with 19 primary chaetae (m3 as mac, others as mic), three trichobothria (m2, a5, m5), and three S-chaetae ( Fig. 28 ). Abd. IV with 28 primary chaetae (A3 and A5 absent), three trichobothria (T2 and T4), 68 S-chaetae (66 elongate and 2 in normal length). Abd. V with 14 primary chaetae (m2, m3, m5 as mac) and three S-chaetae (medial one posterior to m3) ( Fig. 29 ).

Appendages. Anterior face of VT without chaetae, lateral flap and posterior face with two smooth chaetae ( Fig. 30 ). Tenaculum with 4+4 teeth and without basal chaeta ( Fig. 32 ). Trochanter of leg III with one spine.

Ecology. Specimens were found in leaf litter of Calamus thysanolepis .

Remarks. This new species is characterized by chrome yellow to slightly brown pigment on lateral terga and medial transverse band on Abd. IV interrupted by middle line, distal Ant. II–III with dark rings, six mac on posterocentral Abd. IV and five smooth chaetae on posterior VT. It is mostly similar to Homidia insularis ( Carpenter, 1904) by pale chrome yellow pigment, prominent tenent hairs and structure of claw. However, it can be discriminated from the latter by without paired stripes on posterior eye patches and with narrow transverse band on medial Abd. IV. Also, this new species is similar to Homidia sotoi Jordana & Baquero, 2010 in colour pattern and dorsal chaetotaxy of Th. II–Abd. III, but differ from the latter by medially transverse band and without mac A5 on Abd. IV. Detailed differences between these three similar species are listed in table 1.

Figures

FIGURES 1–4. Colour pattern of Homidia chroma sp. nov.: 1–3, adults; 1, lateral view; 2, dorsal view; 3, ventral view; 4, first instar larvae.

FIGURES 5–13. Adults Homidia chroma sp. nov.: 5, basal part of Ant. I; 6, smooth chaetae on basal Ant. II; 7, distal part of Ant. II; 8, Ant. III organ; 9, apical bulb and distal part of Ant. IV; 10, cephalic macrochaetotaxy; 11, labial and postlabial chaetal formula; 12, labial palp; 13, maxillary outer lobe. Scale bar=50 μm. (5, 6, 9, 10, dorsal view; 7, 11, 12, ventral view; 8, 13, lateral view).

FIGURES 14–19. Adults Homidia chroma sp. nov.: 14–16, coxal macrochaetal formula. 14, fore leg; 15, mid leg; 16, hind leg; 17, trochanteral organ; 18, distal part of tibiotarsus and claw of hind leg; 19, chaetotaxy of Th. II–Abd. III tergites. Scale bar=50 μm. (14–16, 18, lateral view; 17, ventral view; 19, dorsal view).

FIGURES 20–27. Adults Homidia chroma sp. nov.: 20, chaetotaxy of Abd. IV–V tergites; 21–23, ventral tube; 21, anterior face; 22, posteriorly distal face; 23, lateral flap; 24. tenaculum; 25, manubrial plaque; 26, basal dens; 27, distal dens and mucro. Scale bar=50 μm. (20, dorsal view; 21, anterior view; 22, 24, 25–27, posterior view).

FIGURES 28–32. First instar larvae of Homidia chroma sp. nov.: 28, chaetotaxy of Th. II–Abd. III tergites; 29, chaetotaxy of Abd. IV–VI tergites; 30, labial and postlabial chaetotaxy; 31, ventral tube; 32, tenaculum. Scale bar=50 μm. (28–29, dorsal view; 30, ventral view; 31–32, posterior view).