Figs 1–21, Tab. 1
Type material. Holotype, female, China: Jiangsu Province, Yancheng, Sheyang County, National Nature Reserve of Red-Crowned Cranes, 26.iv. 2006, collection number C 9465, coll. Ji-Qiang Qu et al. Paratypes: 7 females and 9 males, 12 in alcohol, same data as holotype. Deposited in the Department of Biology, Nanjing University, China.
Description.
Size. Maximum body length: up to 1.5 mm.
Colour. Dorsum of body, antennae and legs violet-black, ventral side paler. Eye patches dark.
Vestiture. Tegumentary granulation: coarse, dorsal of Abd. V with 5–7 (usually 6) granules between p 1 setae.
Antennae. Antennae short, 0.55–0.75 and 0.09–0.16 times as long as cephalic diagonal and body length respectively. Ratio of length of antennal segments as I: II: III: IV = 1: 0.7–1.3: 1.0– 1.4: 1.4–1.8. Ant. IV with simple apical bulb; dorsally with 10 differentiated sensilla, subapical vesicle (os) and microsensillum (ms); ventrally with 3 short and pointed setae inserted in papillae (Figs 10 and 11). Ant. III organ with 2 small rod-like sensilla in separate foveae and two guard sensilla. Ventral microsensillum also present on Ant. III. Ant. II with 13 setae. Ant. I with 8 setae including p seta (Fig. 10).
Head. Tubercles and spines absent. Eyes 8 + 8; eye patch with three setae, Oc 2 longer than Oc 1 and Oc 3 (Fig. 8). Postantennal organ 1.2–2.5 times as large as nearest eye in diameter, composed of 4 lobes, without accessory tubercle (Fig. 8).Labral setal formula 4 /5, 5, 4, lateral setae of anterior row slightly thickened with tip bent inwards, labral margin without papillae (Fig. 5). Ventral cephalic chaetotaxy (after Fjellberg 1998 / 99) with 6 setae in px, 4 in bm, 5 in bl, and 3 in plb (Fig. 2). Labial palp with 5 papillae (A–E) (after Fjellberg 1998 / 99), guard setae a 1, d 1, e 7 and lateral process absent (Fig. 20). Maxilla with 6 lamellae, lamella 1 with long filaments, lamellae 1 and 2 longer than maxillary teeth, lamella 6 obviously longer than lamellae 3 and 5 (Fig. 12). Maxillary outer lobe with 2 sublobal hairs (Fig. 3). Dorsal cephalic chaetotaxy (after Yosii 1960) shown in Fig. 4. Differentiation between microsetae and macrosetae indistinct. Dorsal setae on thoracic and abdominal segments generally arranged in one row (p row), two (a and p rows) or three rows (a, m and p rows). All setae divided into three types: 1) macrosetae on Abd. V–VI (Fig. 6 c, A 1, A 2 … and P 1, P 2 …); 2) microsetae (Fig. 6 b, a 1, a 2 …, m 1, m 2 … and p 1, p 2 …); 3) long, smooth and curved sensilla (Fig. 6 a: s).
Thorax. Dorsal chaetotaxy shown in Fig. 1. Th. I with 3 + 3 setae in p row, usually p 5 longer than p 1 and p 4. Th. II with 3 rows of setae, 6 + 6 setae in a row, as a 1-6; usually 4 + 4 setae in m row, as m 1, m 4-5 and m 7, occasionally m 6 present, m 2 and m 3 absent, m 7 as s; 6 + 6 setae in p row, as p 1–6, p 4 as s. Th. III with 3 rows of setae, 6 + 6 setae in a row, as a 1-2 and a 4–7; 4 + 4 setae in m row, as m 1, m 4-5 and m 7, m 2 and m 3 absent, m 7 as s; 6 + 6 setae in p row, as p 1–6, p 4 as s. No seta on thoracic sterna II–III. Legs with unguis well-developed, with one inner tooth at 3 / 5 distance of its inner edge from base. Unguiculus lance-shaped, with tip of apical filament reaching 1 / 2 distance of inner edge of unguis. Tibiotarsus with one weakly knobbed tenent hair (Fig. 13). Hind leg with 3 setae on subcoxa, 7 (rarely 8) setae on coxa, 7 setae on trochanter, 12 setae on femur, 18 setae on tibiotarsus including tenent hair (Fig. 19).
Abdomen. Dorsal chaetotaxy showed in Fig. 9. Abd. I with three rows of setae, 5 + 5 setae in a row, as a 1-2 and a 4-6; 3 + 3 setae in m row, as m 3-4 and m 7; 7 + 7 setae in p row, as p 1–7, p 5 as s. Abd. II with three rows of setae, 6 + 6 setae in a row, as a 1-2 and a 4-7; 3 + 3 setae in m row, as m 3-4 and m 7; 7 + 7 setae in p row, as p 1–7, p 5 as s. Abd. III with three rows of setae, 7 + 7 setae in a row, as a 1–7; 3 + 3 setae in m row, as m 3-4 and m 7; 7 + 7 setae in p row, as p 1–7, p 5 as s. Abd. IV with three rows of setae, 5 + 5 setae in a row, as a 1–5; 4 + 4 setae in m row, as m 1 and m 3– 5; 5 + 5 setae in p row, as p 1–5, p 4 as s, length ratio of p 4 (s): p 5 = 1.9–2.3: 1. Abd. V with two rows of setae, 5 + 5 setae in a row, as A 1–5; 5 + 5 setae in p row, as P 1–5, P 3 as seta s. Abd. VI with 2 rows of setae, 3 + 3 setae in a row, Note: * the same seta respectively in figs. 10 & 11.
as A 1-3; 2 + 2 setae in p row (Fig. 18). Ventral tube short, with 4 + 4 setae (Fig. 17). Tenaculum with 4 teeth on each ramus, no seta on corpus (Fig. 7). Manubrium (posterior) usually with 14 (rarely 13 or 15) setae on each side. Dens posteriorly with coarse granules (Fig. 21) and 7 setae, ratio of length of subbasal seta to basal seta as 2.0– 2.7: 1. Mucro with apex slightly curved, outer lamella long and slender, without inner lamella (Fig. 14). Length ratio of dens to mucro = 1.8–2.5 (mean 2.2): 1.
Two short, straight anal spines on Abd. VI, slightly longer than their basal papillae (Fig. 18). Male and female genital plates respectively with 20–34 and 16–22 setae (Figs. 15 and 16).
Ecology. In soil under the salt–tolerant plant, Suaeda salsa (L.), in the salt marsh at intertidal zone.
Etymology. The new species is named after the type locality of Sheyang County.
Remarks. The new species is characterised by p 4 seta on Abd. IV as sensillum (p 4 = s), which can distinguish it from all known species in the manubrialis group of the genus Hypogastrura except H. matura (Folsom) (sensu Christiansen & Bellinger, 1998). However, the new species has 10 dorsal sensilla on Ant. IV and coarse granules on dens whereas H. matura possess 8 sensilla on Ant. IV and fine granules on dens. The North American species H. utahensis (Wray) (sensu Christiansen & Bellinger, 1998) may be another species with the character (p 4 = s) similar to the new species; however, it differs from the new species in the presence of trilobed postantennal organ, one or two setae in m row on Abd. V, 6–8 weakly differentiated sensilla on Ant. IV, the absence of p seta on Ant. I.
The new species is similar to H. manubrialis (Tullberg) (sensu Babenko et al. 1994, Thibaud et al. 2004) in the following characters: 1) Th. II and Abd. IV without m 2, Abd. V without m seta; 2) claw with a single inner tooth; 3) tibiotarsus with a single weakly knobbed tenent hair; 4) dens with 7 setae. The new species is also close to H. arctandria Fjellberg, 1988 and H. assimilis (Krausbauer) (sensu Babenko et al. 1994, Thibaud et al. 2004). However, the new species could be easily distinguished from the above mentioned three species by the characters showed in Tab. 1.
Among the five Chinese species described in the genus Hypogastrura, only H. yosii Stach, 1964 is the member of H. manubrialis group. However, it differs from the new species in the presence of 6 dorsal sensilla on Ant. IV, the absence of p seta on Ant. I and inner tooth on claw.
TABLE 1. Differences between H. sheyangensis sp. nov. and the most similar three species in H. manubrialis – group.