Thalassaphorura guangxiensis, Sun & Bedos & Deharveng, 2017

Sun, Xin, Bedos, Anne & Deharveng, Louis, 2017, Two new species of the genus Thalassaphorura Bagnall, 1949 (Collembola: Onychiuridae) from South China, with an updated key to world species of the genus, Zootaxa 4338 (2), pp. 319-332 : 324-326

Thalassaphorura guangxiensis sp. nov.

Figs 14–21

Diagnosis. Pseudocellar formula as 32/122/33343 dorsally and 11/000/01110 ventrally, one pso on each subcoxae 1, five guard papillae on AIIIO, 4+4 p-chaetae between inner posterior pso on head, 5+5 chaetae on Th. I tergum, unguiculus without basal lamella and the unguiculus/unguis ratio is 0.4–0.5, Th. I–III sterna with 0+0, 1+1, 1+1 chaetae, AS set on small papillae and the AS /unguis ratio is 0.3, and small body size.

Type material. holotype female and 7 paratypes (4 females and 3 males). China: Guangxi: Hechi: Huangjiang Xian: Xiazhai village : near Mashan Dong , 19 May 2007, secondary forest, litter, berlese extraction after sifting, Louis Deharveng & Anne Bedos leg. (sample CHIgx 07-19-03, long. 108.05865°, lat. 25.15855°, alt. 335 m). Type specimens (holotype, 2 females paratypes and 2 males paratypes) are deposited in CAS-IGA, Changchun and 2 females and 1 male paratypes in MNHN, Paris.

Other material. Ibidem, numerous specimens in alcohol.

Description. Holotype length 0.78 mm, length of paratypes: 0.76–0.92 mm in female and 0.62–0.71 mm in male. Shape of body cylindrical, Abd. III–IV parallel ( Fig. 14 ). Color in alcohol white. AS set on small papillae, and the AS /unguis ratio is 0.3 ( Figs 14 & 21 ).

Granulation fine and homogenous, without coarse granules even around dorsal pseudocelli, on dorsal part of antennae, and on Th. I–III. Antennae almost as long as head. Ant. I with 9 chaetae, Ant. II with 13 chaetae. AIIIO consisting of five guard chaetae, five papillae, two smooth sensory rods, and two smooth and spherical sense clubs ( Figs 15 & 16 ), ventro-lateral ms present. Ant. IV with subapical organite, without differentiated S-chaetae; basolateral ms above the second proximal row of chaetae ( Fig. 15 ).

PAO with 14–16 simple vesicles arranged in two rows perpendicularly to long axis of organ ( Fig. 14 ). Dorsal chaeta d0 on head present. 4+4 p-chaetae between inner posterior pso on head, p1 anterior to others ( Fig. 14 ). Labral formula of chaetae: 4/1,4,2. Maxillary palp simple with one basal chaeta and two sublobal hairs. Labial palp of type AC, papillae A to E with 1, 4, 0, 3 and 2 guard chaetae respectively ( Fig. 17 ). Labium with 6 proximal, 4 baso-median (E, F, G, and f) and 6 baso-lateral (a, b, c, d, e, e') chaetae ( Fig. 19 ). Postlabial chaetae 4+4 along ventral groove ( Fig. 19 ).

Dorsal pso formula as 32/122/33343, and ventral as 11/000/01110 ( Figs 14 & 18 ). Subcoxa 1 of legs I, II and III with 1, 1 and 1 pso respectively. Parapseudocelli only visible on Abd. I sternum at the base of VT as 1+1. Pseudopore formula: 00/011/11110 dorsally and 00/111/0001m0 ventrally ( Figs 14 & 18 ).

Ordinary chaetae differentiated in micro-, meso- and macrochaetae. S-chaetae weakly thickened but distinguishable from ordinary chaetae, S-chaetae formula: 11/011/222121 dorsally and 11/000/000100 ventrally ( Figs 14 & 18 ). Th. I tergum with 5+5 chaetae ( Fig. 14 ). Th. II–III with lateral ms. Th. II to Abd. III terga each with 3+3 paired axial chaetae each ( Fig. 14 ). Abd. IV tergum with unpaired axial chaeta m0, Abd. V tergum with a0, Abd. VI tergum with a0 and m0 ( Fig. 14 ). Th. I–III sterna with 0+0, 1+1, 1+1 chaetae.

Subcoxae 1 of legs I–III with 3, 4, 4 chaetae, and subcoxae 2 with 1, 4, 4 chaetae respectively. Coxae of legs I, II and III with 3, 10 and 13 chaetae, trochanters with 9 chaetae and femora with 14 chaetae each. Tibiotarsi I, II and III with 18 (1, 8, 9) chaetae each ( Fig. 20 ). Chaeta M present. Unguis without inner or lateral denticles. Unguiculus without basal lamella and the unguiculus/unguis ratio is 0.4–0.5 ( Fig. 20 ). Ventral tube with 6+6 distal and 1+1 proximal chaetae, without anterior chaetae. Modified chaetae in males ventrally absent. Furca reduced to finely granulated area, with 4 small dental chaetae arranged in two rows posteriorly; one manubrial row of chaetae present ( Fig. 18 ). Genital plate with 11–18 ante-genital and 2 genital chaetae in females, 12–20 circum-genital and 8 genital chaetae in males. Anal valves with numerous acuminate chaetae; each lateral valve with chaetae a0 and 2a1; upper valve with chaetae a0, 2a1, 2b1, c0, 2c1, 2c2.

Etymology. The species is named after type locality, province Guangxi in China.

Distribution. Only known from the type locality.

Discussion. The new species is most similar to the Guangxi species T. reducta in having small body size and anal spines, dorsal pso formula as 32/122/33343, 1 pso on subcoxae 1, 9 chaetae in the distal whorl of tibiotarsi, 4+4 p-chaetae between inner posterior pso on head; but they could be differentiated by the ventral pso formula (11/ 000/01110 in the new species versus 11/000/01000 in T. reducta ), the number of chaetae on subcoxae 1 of leg I (3 in the new species versus 2 in T. reducta ), the number of anterior chaetae on ventral tube (absent in the new species versus 1+ 1 in T. reducta ). The new species possesses the same dorsal pso formula as T. bapen and T. guangdongensis ; however, they can be recognized easily by the ventral pso formula, the number of pso on subcoxae 1 and other combined characters ( Table 2).

Figures

FIGURES 14 – 18. Thalassaphorura guangxiensis sp. nov. 14, dorsal side of body; 15, antenna; 16, clubs, and papillae of AIIIO; 17, labium; 18, ventral side of Abd. II – IV. Scales: 0.1 mm (14, 15, 18), 0.01 mm (16 – 17).

FIGURES 19 – 21. Thalassaphorura guangxiensis sp. nov. 19, ventral side of head; 20, tibiotarsus of leg II; 21, AS. Scales: 0.1 mm (19), 0.01 mm (20 – 21).