Pseudachorutes cheni, Shi, Shidi, Jiang, Jigang & Pan, Zhi-Xiang, 2008

Shi, Shidi, Jiang, Jigang & Pan, Zhi-Xiang, 2008, A new species of Pseudachorutes Tullberg (Collembola, Neanuridae) from China, Zootaxa 1755, pp. 57-60 : 57-60

Pseudachorutes cheni sp. nov.

Figs 1–14

Type material. Holotype, female. China: Zhejiang Province, Taizhou City, Shanmen County, in a grove of orange trees at Mountain Qiushui, 20.xi.2005, collection number S1034, coll. Zhi-Xiang Pan. Paratypes: 3 females, 2 males, 4 juveniles, the same data as holotype. Deposited in the Department of Biological Science, Taizhou College, China.

Description. Body length 1.0– 2.15 mm, (holotype, female: 1.5 mm; paratypes, three females: 1.5–2.15 mm, two males: 1.75–1.9mm, four juveniles: 1.0– 1.65mm). Body color gray to dark gray (in alcohol). Tegumentary granulation uniform, granules conical.

Head. Cephalic setae smooth, short ( Fig. 1 ). Eyes 8+8. Postantennal organ 2.4–2.7 times as large as nearest eye, composed of 14–17 lobes arranged in an ellipse ( Fig. 8 ). Antenna short, respectively 0.6–0.7 and 0.14–0.18 times as long as cephalic length and body length, dorsal side of third and fourth segments fused ( Fig. 4 ). Antennal segment length ratio as I: II: III + IV = 1: 0.9–1.1: 2.5–2.7. Ant. IV with trilobed apical bulb; dorsally with 6 differentiated sensilla, subapical organite (os) and microsensillum (ms); ventrally with some pointed setae ( Figs 4 and 7 ). Ant. III sensory organ with two small internal rod-like sensilla in separate foveae and two guard sensilla; ventral microsensillum (ms) present. Ant. II with 12 setae, Ant. I with 7 setae ( Fig. 4 ). Mandible distinctly tridentate, middle tooth smaller than the basal and apical teeth ( Fig. 5 ). Maxilla with crochet-like apical part, without denticle ( Fig. 6 ). Labral chaetotaxy as 4/3, 5, 2; outer prelabral setae longer than labral setae ( Fig. 9 ). Labium elongated apically, apex narrowly rounded, without spine-like setae and short sensilla ( Fig. 11 ).

Thorax. All setae (except setae s) short and smooth ( Fig. 1 ). Pronotum with 3+3 setae in one row. Mesonotum and metanotum each with 2+2 smooth setae s, 3–4 times as long as common seta. Mesonotum with seta a2 and microsensillum (ms). Metanotum without seta a2 and microsensillum ( Fig. 1 ). Thoracic sterna without setae. Unguis with one inner tooth in the basal one fourth to one third of its length ( Fig. 13 ). Lateral teeth absent ( Fig. 14 ). Unguiculus absent. Tibiotarsi without differentiated tenent hairs. Fore leg with 1 seta on 1.subcoxa, no seta on 2.subcoxa, 3 setae on coxa, 6 on trochanter, 11 (rarely 10 or 12) on femur, 19 on tibiotarsus. Middle leg with 2 setae on 1.subcoxa, 2 on 2.subcoxa, 3 on coxa, 6 on trochanter, 11 on femur, 19 on tibiotarsus. Hind leg with 3 setae on 1.subcoxa, 2 on 2.subcoxa, 8 on coxa, 6 on trochanter, 11 on femur, 18 on tibiotarsus ( Fig. 13 ).

Abdomen. Abd. I–III dorsally each with 2 +2 setae s, Abd. IV dorsally with 1+1 setae s, Abd. V with 1+1 setae s in p3 position ( Fig. 2 ). Seta a2 absent on Abd. I–V, setae s 3-4 times as long as common setae. Abdomen sternum I without setae, abdomen sternum II with 5+5 setae, abdomen sternum III with 8+8 setae ( Fig. 12 ). Ventral tube with 4+4 (sometimes 4+5) setae ( Fig. 12 ). Tenaculum with 3+3 teeth, no setae on corpus. Manubrium usually with 9–10+9–10 posterior setae. Dens granulated, with 6 setae ( Fig. 3 ). Mucro without outer and inner lamellae ( Fig. 3 ). Length ratio of manubrium: dens: mucro = 4.0–4.5: 3.0–3.1: 1. Female genital plate with about 30 setae ( Fig. 10 ).

Ecology. In soil under a stack of decayed grass in the orange grove.

Etymology. The new species is named after Prof. Jian–Xiu Chen from Nanjing University, China. His assistance was helpful for our research.

Remarks. The new species is very similar to P. andrei Weiner & Najt, 1985 . Both species have Ant. IV with 6 differentiated sensilla and trilobed apical bulb, Ant. I with 7 setae, Ant. II with 12 setae; unguis with one inner tooth, without lateral teeth; dens with 6 setae, mucro without lamellae; postantennal organ 2.4–2.7 times as large as nearest eye, composed of 14–17 lobes; tibiotarsi I–III with 19, 19, 18 setae respectively, without tenent hairs; setae s on thoracic and abdominal terga 3–4 times as long as ordinary setae; ventral tube with 4+4 setae; tenaculum with 3+3 teeth. However, P. cheni has 2+2 setae s on Abd. I–III, a distinctly tridentate mandible, and a crochet-like maxilla without denticles; whereas, P. andrei has only 1+1 setae s on Abd. I–III, possesses a minute middle tooth close to the apical tooth on the mandible, and two denticles on the maxilla. The new species resembles the poorly described Himalayan species P. anomalus Imms, 1912 by the presence of a postantennal organ of approximately 17 lobes, trilobed apical antennal bulb, mucro without inner and outer lamellae, tibiotarsus without differentiated tenent hair, and unguis without lateral teeth. Pseudachorutes cheni differs from P. anomalus in having a toothed unguis (teeth absent in P. anomalus ) and a manubrium longer than the dens (ratio 4.3: 3 in the new species and equal size in P. anomalus ). Pseudachorutes cheni can be separated from all other known Pseudachorutes spp. by combination of the following characters: mandible tridentate; maxilla crochet-like without denticles; oval postantennal organ with 14–17 lobes; 6 differentiated sensilla on the dorsal part of Ant. IV; one inner tooth and no lateral teeth present on unguis and Abd. I–III with 2+2 setae s.

Figures

FIGURES 1 – 4. Pseudachorutes cheni sp. nov.: 1, dorsal chaetotaxy of head and thorax; 2, dorsal chaetotaxy of abdomen; 3, furcula; 4, Ant. I – IV, dorsal view.

FIGURES 5 – 14. Pseudachorutes cheni sp. nov.: 5, mandible; 6, maxilla; 7, Ant. IV, ventral view; 8, postantennal organ and eyes; 9, labrum; 10, female genital plate; 11, labium; 12, abdomen, ventral view; 13, hind leg; 14, unguis III, dorsal view.