Pseudachorutes polychaetosus, Gao, Yan & Palacios-Vargas, José G., 2008

Gao, Yan & Palacios-Vargas, José G., 2008, A new species of genus Pseudachorutes Tullberg, 1871 (Collembola: Neanuridae: Pseudachorutinae) from China, Zootaxa 1895, pp. 53-58 : 54-55

Pseudachorutes polychaetosus sp. nov.

( Figs 1–11 )

Length of body length (n=3): 1050µm (range: 950–1130µm). Holotype, 1130µm. Colour of the body dark grey. Cuticular granulations medium and homogenous. All the body setae smooth, but of several types. Length of long macrosetae (M) from 62–100µm and short microsetae (m) 25–37µm, sensorial setae (ss) short and slender, 25–30µm ( Figs 1 and 8 ).

Antennae 0.9 as long as head. Antennal segment I with 7 setae, antennal segment II with 14 setae. Antennal segments III and IV dorsally fused. Ratio of antennal segments I:II:III+IV as 1:1:2. Sensory organ of antennal segment III with two small straight internal sensilla under a cuticular fold, two guard sensilla (the sgv is about 0.9 times shorter than sgd) and 1 microsensillum (ms) close to ventral guard sensillum. Ant. IV with trilobed apical bulb, 6 cylindrical sensilla (S), seta “i”, microsensillum and subapical organite ( Fig. 2 ); and with a distinct ventral file with about 30 short pointed setae ( Fig. 3 ).

Postantennal organ elliptical, composed of 10 simple vesicles, 1.1 times longer than the adjacent ocelli. Eye patch with 8+8 small ocelli ( Fig. 1 ), F & G 0.9 times smaller than others.

Buccal cone elongated. Mandible with three slender teeth, the middle one minute ( Fig. 4 ). Maxilla styliform, with two blades, one of them with apical tooth ( Fig. 5 ). Labrum with 11 setae arranged as 2, 4, 3, 2; 4 prelabrals. Labium with similar chaetotaxy to that of the genus ( Deharveng, 1983), but with seta B missing, and seta L on a small tubercle ( Fig. 6 ).

Dorsal chaetotaxy as in Figs 1 and 8 . Seta a0 on the head present, unpaired seta d2 present. Th. I with 4+4 dorsal setae and 1 on each subcoxa 1. Setae a2 present on Th. II, but absent from Th. III to Abd. V. Setae m4 and m6 present. Abd. IV with distinct hypertrichosis having at least three rows of setae. S setae on the body in positions p4 and m7 on Th. II and Th. III, and p5 from Abd. I to Abd. IV and p3 on Abd. V. Sensorial formula of the body 022/11111. Sensory setae subequal to ordinary microsetae but more slender. Ratio of length of longest Abd. V setae to inner unguis as 2.2. Thoracic sterna without setae, but paratergal areas of Th. II and III with four setae on each side. Ventral tube with 4+4 setae ( Fig. 10 ). Male genital plate with 3+3 pregenital setae, 21 circumgenital setae and 4+4 eugenital spine-like modified setae ( Fig. 11 ). Males bilaterally symmetrical sexually dimorphic with a pair of ventral structures present on abdominal segments IV ( Fig. 10 ), each with 9 setae.

Tibiotarsi I, II, III with 19, 19, 18 setae respectively, lacking tenent hairs. Unguis with two inner teeth (one large, one small) in basal third; 2 lateral teeth, one basal, the other in the basal third. Ratio of tibiotarsus III and unguis about 1.5. Unguiculus absent ( Fig. 7 ). Femora I, II, III with 12, 12, 11 setae respectively, two setae on each leg longer. Trochanter I, II and III with 6 setae each. Coxae I, II, III with 3, 7, 7 setae respectively. Subcoxae 2. I, II, III with 0, 3, 3 setae respectively. Subcoxae 1. I, II, III with 1, 3, 3 setae respectively.

Furcula well developed. Manubrium with 8 pairs of setae, two longer. Dens dorsally with moderate granulation and with 6 setae, ventral side with a triangular smooth area. Mucro 1.4 times shorter than dens, boatshaped with two lateral lamella and with a hook-like end ( Fig. 9 ). Tenaculum with 3+3 teeth ( Fig. 9 ). Anal spines lacking.

Etymology. The name refers to the presence of abundant setae in this species.

Variation: (encircled in Fig. 1 )

On the holotype, two microsetae between m2 and m3 present on the right side, possibly representing a rare asymmetry, and a distinctly raised anterior subtergite of the mesothorax, with two setae possibly a2 (a2') displaced anteriorly ( Fig. 1 ).

Figures

FIGURES 1 – 7. Pseudachorutes polychaetosus sp. nov. 1, dorsal chaetotaxy of the head and thorax; 2, left antennal segments III – IV, dorsal view; 3, left antennal segments III – IV, ventral view; 4, mandible; 5, maxilla; 6, labium; 7, femur and tibiotarsus III.

FIGURES 8 – 11. Pseudachorutes polychaetosus sp. nov. 8, dorsal chaetotaxy of the abdomen; 9, furcula and tenaculum; 10, ventral abdomen showing ventral organ of male; 11, male genital plate.