Hypogastrura hexasetata, Jiang & Yin, 2010

Jiang, Jigang & Yin, Wenying, 2010, Two new Hypogastrura species (Hypogastruridae, Collembola) from China, Zootaxa 2542 (1), pp. 48-60 : 49-53

Hypogastrura hexasetata sp. nov.

Figs 1–18 , Tab. 1 and 3

Type material. Holotype male, China, Hubei Province, Xianfeng County, Laoliba Village . 1000 m alt. 23.ix.1997, collector unknown, mounted on slide . Paratypes, three females (subadult, mounted on slides) and one specimen in alcohol, the same data as holotype. All types deposited in Institute of Plant Physiology & Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences .

Description. Body length 1.4–1.6mm. Body color in alcohol grey. Integumentary granules fine and uniform. 8–10 granules between setae p 1 on Abd. V.

Dorsal chaetotaxy of head, thorax and abdomen as in Figs 1, 3 and 4 . Ventral cephalic chaetotaxy (after Fjellberg, 1999) with 6 proximal, 4 basomedian, 5 basolateral, and 3 postlabial setae ( Fig. 10 ). Th. I with 3+3 setae. Th. II with m 2 and m 6. Th. III without m 2 and with m 6. Sternal setae absent. Abd. IV plurichaetotic, ratio p 5 (s): p 6 as 1.7–1.9: 1.

Ant. I with 7 setae, without p seta. Ant. II with 13 setae. Ant. III with microsensillum (ms) on ventral side, Ant. III organ with 2 short rods in separate foveae and 2 guard sensilla. Ant. IV with simple subapical bulb and 8–10 (mostly nine, three outer and six inner) dorsolateral sensilla, microsensillum (ms), i seta and subapical organite (os), ventral file with 30–55 short and pointed setae ( Figs 7–9 ).

Eyes 8+8 ( Figs 1–2 ). Postantennal organ with 4 lobes, subequal in diameter (about 0.85–0.95) to nearest eye, accessory tubercle absent ( Fig. 2 ).

Labrum without papillae on distal margin, setal formula as 4 /5, 5, 4, setae in anterior row considerably longer than other setae ( Fig. 12 ). Labial palp with 5 papillae (A–E) (after Fjellberg, 1998/99), guard setae a 1, b 1–4, d 2–4, e 1–6 present; lateral process developed ( Fig. 15 ). Maxilla with lamellae 1, 2, 4 and 5 distinctly longer than maxillary teeth, lamella 1 with denticles on inner side and knobbed denticles on the middle part of outer side; lamella 2 with long marginal filaments and no denticles, lamella 3 distinctly shorter than maxillary teeth, with short marginal filaments; lamella 4 with denticles on inner side and knobbed denticles on outer side, dorsally with marginal filaments; lamella 5 with small marginal denticles on basal half of inner side, with marginal filaments on ventral side and on apical half of dorsal side; lamella 6 shorter than maxillary teeth, without denticles and filaments ( Figs 13–14 ). Maxillary outer lobe with one sublobal hair ( Fig. 5 ).

Unguis with 1 inner tooth at 1/2 distance of its inner edge and 2 pairs of lateral teeth. Unguiculus with broad basal lamella, tip of apical filament reaching 1/2 distance of inner edge of unguis. Tibiotarsus without distinctly differentiated tenent hair, foot complex of hind leg shown in Fig. 18 . Number of setae on each segment of legs as in Table 1.

Ventral tube short, with 4+4 lateral setae ( Fig. 16 ). Tenaculum with 4+4 teeth ( Fig. 17 ).

Manubrium with 9–10 (mostly 9) posterior setae on each side ( Fig. 6 ). Dens with 6 posterior setae. Mucro distinctly carinated, with small apical outer lamellae, without inner lamellae, apex up-turned ( Fig. 6 ). Ratio dens: mucro as 2.8 (2.5–3.0): 1. Anal lobes with 12–19 setae. Two anal spines on Abd. VI short and curved, subequal to their basal papillae ( Figs 4 and 11 ).

Ecology. Found in soil under decaying leaves.

Etymology. The name refers to having six dental setae.

Remarks. Though the new species H. hexasetata has no differentiated tenent hair on tibiotarsus, it possesses most characters of the trybomi group. The new species is very close to H. hargrovei Skarży ṅski, 2007. They share highly modified mouthparts, postantennal organ slightly smaller than neighboring eyes, maxillary outer lobe with only one sublobal hair and dens with 6. The new species can be discriminated from the latter as follows: head ventrally with 3+3 axial setae, Ant. IV with a strong ventral file (30–55 setae), Th. II with m 2 setae, tibiotarsus without differentiated tenent hair. In H. hargrovei , head ventrally has 2+2 axial setae, Ant. IV has a weak ventrally file (about 10 setae), Th. II has not m 2 setae, tibiotarsus with differentiated tenent hair. The new species is also close to H. maxillosa Babenko, 1994 . They share maxillary lamellae 1, 2, 4, 5 prominently longer than maxillary teeth, unguis with an inner tooth and 2 pairs of lateral teeth, mucro with outer lamella. H. hexasetata sp.nov. can be separated from the latter by tibiotarsi I–III having not differentiated tenent hairs, 6 setae on dens, m 2 seta on Th. II present, Ant. IV usually having 9 dorsal sensilla. In H. maxillosa , tibiotarsi I–III each has one differentiated pointed tenent hair, 7 setae on dens, no m 2 setae on Th. II, Ant. IV dorsally with eight sensilla. The new species differs from other members of the trybomi group by having highly modified mouthparts and by having only 1 sublobal hair on the maxillary outer lobe. Though the information of mouthparts of H. ireneae and H. maynardi is unavailable, H. hexasetata sp. nov. is easy to be distinguished due to small postantennal organ (slightly smaller than nearest eye), while H. ireneae and H. maynardi have large ones (about twice as large as nearest eye) (Skarżyṅski, 2007). The new species is also similar to H. coprophila Stach, 1960 from Afghanistan in having body setae hardly differentiated, tibiotarsi without differentiated tenent hairs, mucro with outer lamella. It differs from H. coprophila by having 6 setae on dens, 8–10 sensilla on Ant. IV and 2 pairs of lateral teeth on unguis (versus seven setae on dens, 5 sensilla on Ant. IV and no lateral tooth on unguis in H. coprophila ). For difference from other species of the group see the key and Table 3.

Figures

FIGURES 1–6. Hypogastrura hexasetata sp. nov.: 1, dorsal cephalic chaetotaxy; 2, postantennal organ and eyes; 3, dorsal thoracic chaetotaxy; 4, dorsal abdominal chaetotaxy; 5, maxillary outer lobe; 6, furcula.

FIGURES 7–10. Hypogastrura hexasetata sp. nov.: 7, Ant. III–IV, dorsal view; 8, Ant. I–II; 9, Ant. III–IV, ventral view; 10, ventral cephalic chaetotaxy.

FIGURES 11–18. Hypogastrura hexasetata sp. nov.: 11, anal spines on Abd. VI; 12, labrum; 13, maxilla, inner view; 14, maxilla, dorsal view; 15, labial palp; 16, ventral tube; 17, tenaculum; 18, femur, tibiotarsus and claw of hind leg.