Hypogastrura quadritenenta, Jiang, Jigang & Chen, Jian-Xiu, 2008

Jiang, Jigang & Chen, Jian-Xiu, 2008, A new species and a new species record of Hypogastrura (Collembola: Hypogastruridae) from China, Zootaxa 1846, pp. 47-54 : 49-53

Hypogastrura quadritenenta , sp. nov.

( Figures 1–22 , Table 1–2 )

Type material. Holotype, male, China: Jiangsu Province: Nanjing: Nanjing Arboretum, 13.x.2005, collection number C9311, coll. Jigang Jiang. Paratypes, three females and two males, the same data as Holotype. All types deposited in the Department of Biology, Nanjing University.

Description. Body length 1.7–2.0mm, female 1.9–2.0mm, male 1.7–1.8mm.

Body colour blackish violet.

Integumentary granules fine and uniform. Dorsum of Abd. V with 10–15 granules between p1 setae.

Head. Tubercles and spines absent. Eyes 8+8, eye patch with three setae, Oc2 longer than Oc1 and Oc3 ( Fig. 10 ). Antennae short, Ratio of length of antenna:cephalic diagonal:body = 1:1.5–1.8:8.5–10.0. Ratio of length of antennal segments as I:II:III:IV = 1.0:0.7–1.4:0.7–1.7:1.3–1.8. Ant. I with seven setae and without p seta. Ant. II with 11–16 (mostly13) setae. Ant. III with microsensillum on ventral side, Ant. III organ with two short rods in separate foveae and two guard setae. Antennal eversible sac absent between Ant. III and IV. Ant. IV with simple subapical bulb and four (three outer and one inner) dorsolateral sensilla and two ventral sensilla near the subapical bulb; microsensillum and subapical organite also present ( Figs. 4 and 5 ). Postantennal organ composed of four lobes, about 0.7–0.9 times as large as the nearest eye in diameter, accessory tubercle present ( Fig. 10 ). Dorsal cephalic chaetotaxy (after Yosii 1960 ) shown in Fig. 1 . Microsetae and macrosetae weakly differentiated, v2 larger than v1, p3 and p5 larger than p1, p2 and p4. Labrum with four distinct rounded papillae on distal margin, setal formula as 4 (rarely 2 or 3)/5, 5, 4 ( Fig. 13 ). Ventral cephalic chaetotaxy (after Fjellberg, 1998/99) with six proximal (px), four basomedian (bm), five basolateral (bl), and three postlabial (plb) setae ( Fig. 14 ). Labial palp with five papillae (A–E) (after Fjellberg, 1998/99), guard setae a1, b1–4, d2–4, e1–6 present; d1, e7 and lateral process absent ( Fig. 11 ). Maxilla of the H. tullbergi type. Lamella 1 with denticles and subequal to maxillary teeth in length; lamellae 2 and 3 with marginal filaments and no denticles; lamellae 4, 5 and 6 with denticles, lamella 4 with rough ventral marginal denticles, lamella 5 with dorsal marginal filaments ( Fig. 9 ). Maxillary outer lobe with two sublobal setae ( Fig. 15 ).

Thorax. Dorsal chaetotaxy shown in Fig. 2 . Th. I with 3+3 setae in p row, p5 slightly longer than p1 and p4. Th. II with three rows of setae; each row having 6+6 setae, respectively as a1-6, m1-5 and m7, and p1-6, m6 absent, m7 and p4 as sensilla. Th. III with three rows of setae, 6+6 setae in a row, as a1-6; 4+4 setae in m row, m2, m4 and m6 absent, m7 as sensillum; 6+6 setae in p row, as p1-6, p4 as sensillum, length ratio of p4 (s) to p5 as 1.6–1.8:1. No setae on sternum. Unguis developed, with one tiny inner tooth at 2/3 distance of its inner edge from base, and without lateral teeth. Unguiculus with basal lamella broad and bow-shaped, tip of apical filament reaching 2/3–4/5 distance of inner edge of unguis. Foot complex of fore leg and mid leg shown in Fig. 20 and Fig. 21 respectively; hind leg shown in Fig. 22 . Number of setae on each segment of legs see Table 1 .

Abdomen. Dorsal setae weakly differentiated into macrosetae and microsetae ( Fig. 3 ). Abd. I with three rows of setae, 5+5 setae in a row, as a1-2 and a4-6, a3 absent; 3+3 setae in m row, as m3-4 and m7; 7+7 setae in p row, as p1-7, p5 as sensillum. Abd. II and III respectively with three rows of setae, 6+6 setae in a row, as a1-2 and a4-7, a3 absent; 3+3 setae in m row; as m3-4 and m6;7+7 setae in p row, p5 as sensillum. Abd. IV with three rows of setae, each row having 6+6 setae, as a1-2 and a4-7, m1-6 and p1-6, a3 absent, p5 as sensillum, Ratio of length of p5 (s):p6 = 2.0–2.1:1. Abd. V with two rows of setae, each row having 5+5 setae, as a1-5 and p1-5, p3 as sensillum. Abd. IV and V without knobbed macrosetae. Abd. VI with two rows of setae, 3+3 setae in a row, 2+ 2 in p row; macrosetae lateral to anal spines pointed to weakly knobbed ( Figs. 3 and 12 ). Ventral tube short, with 4+4 setae ( Fig. 16 ). Tenaculum with 3+3 teeth, no seta on corpus ( Fig. 17 ). Manubrium with 11–13 posterior setae on each side ( Fig. 6 ). Dens with six posterior setae, ratio of length of subbasal seta to basal seta as 2.0– 3.4:1. Mucro slightly curved, without inner and outer lamellae, with distinct carina, apex hook-like ( Figs. 6, 7 and 8 ). Ratio of length of dens:mucro = 3.2–3.8 (mostly 3.5):1; ratio of length of dens plus mucro:unguis III = 2.4–2.6:1. Genital plates of male and female respectively with 35–42 and 26–28 setae ( Figs. 18 and 19 ). Anal lobes with 13–19 setae. Two anal spines on Abd. VI short and curved, longer than their basal papillae ( Figs. 3 and 12 ).

Ecology. Found in soil under decaying leaves and sticks in deciduous forest.

Etymology. The name refers to the four tenent hairs present on the tibiotarsi of middle and hind legs.

Remarks. The new species, Hypogastrura quadritenenta , belongs to the H. viatica group because it possesses all the characters of the species group. It can be separated from other members, except the Polish species H. brevifurca Skarzynski, 2000 , by the number of tenent hairs. In the viatica -group, only the new species and H. brevifurca have 2, 4, 4 knobbed tenent hairs on tibiotarsi I–III. The new species is also similar to H. brevifurca in having body setae weakly differentiated into macrosetae and microsetae, body granulation fine and uniform, Ant. I with seven setae and no p seta, Ant. IV with four dorsal and two ventral sensilla, unguis with inner tooth and no lateral teeth. However, it can be distinguished from H. brevifurca by the setae on dens, dorsal abdominal chaetotaxy, labral marginal papillae, knobbed macrosetae on Abd. IV–V, and shape of basal lamella on unguiculus. The new species is also similar to the Mexican species H. leo Palacios-Vargas, 1986 in having body setae weakly differentiated into macrosetae and microsetae, body granulation fine and uniform, Ant. I with seven setae and no p seta, Ant. IV with four dorsal sensilla, labrum with four rounded marginal papillae, dens with six setae, and unguis with inner tooth and no lateral teeth. However, it can be separated from H. leo by the tenent hairs on tibiotarsi I–III, basal lamella of unguiculus, lateral sensilla on Abd. I–II and knobbed macrosetae on Abd. IV–V. A comparison of the characters of the new species, H. brevifurca and H. leo is given in Table 2 .

* information offered by Prof. José Palacios-Vargas after re-examining the type specimens.

Figures

FIGURES 1 – 12. Hypogastrura quadritenenta, sp. nov. 1, dorsal cephalic chaetotaxy. 2, dorsal thoracic chaetotaxy. 3, dorsal abdominal chaetotaxy. 4, Ant. III – IV, dorsal view. 5, Ant. IV, ventral view. 6, furcula. 7, mucro and dens. 8, mucro, dorsal view. 9, maxilla. 10, postantennal organ and eyes. 11, labial palp. 12, Abd. VI.

FIGURES 13 – 22. Hypogastrura quadritenenta, sp. nov. 13, labral setae and papillae. 14, ventral cephalic chaetotaxy. 15, maxillary outer lobe. 16, ventral tube. 17, tenaculum. 18, male genital plate. 19, female genital plate. 20, tibiotarsus, and foot complex of fore leg. 21, tibiotarsus and foot complex of mid leg. 22, hind leg.

Tables

TABLE 1. Number of setae on each segment of legs.

Leg	subcoxa I subcoxa II coax	Trochanter	Femur	tibiotarsus (including tenent hairs)	tenent hairs
fore leg	1 0 3	7	14 (13)	19	2
mid leg	2 3 8 (7)	7	13 (12)	19	4
hind leg	3 3 7 (8)	7	12	18	4

TABLE 2. Comparison of Hypogastrura quadritenenta, sp. nov. with two similar species.

Character	quadritenenta , sp. nov.	brevifurca	leo
dorsal setae on dens	6	5	6*
seta a3 on Abd. IV	absent	present	absent
seta m2 on Abd. IV	present	absent	present
lateral sensillum on Abd. I–II	absent	absent	present
tenent hairs on tibiotarsi I–III	2, 4, 4	2, 4, 4	3, 3, 4*
rounded papillae on labrum	4	6	4*
length ratio of dens + mucro / unguis III	2.4–2.6:1	1.15–1.35:1	?
m row setae on Abd. V	absent	present	absent
knobbed macrosetae on Abd. IV–V	absent	present in male	present
macrosetae lateral to anal spines	pointed or weakly knobbed	distinctly knobbed	distinctly knobbed
unguiculus basal lamella	broad	narrow	very narrow*