Sinoncopodura, Yu & Zhang & Deharveng, 2014

Yu, Daoyuan, Zhang, Feng & Deharveng, Louis, 2014, A remarkable new genus of Oncopoduridae (Collembola) from China, Journal of Natural History (J. Nat. Hist.) 48 (33 - 34), pp. 2069-2082 : 2070-2071

Sinoncopodura gen. nov.

Type species: Sinoncopodura nana sp. nov.

Diagnosis

Body size small, about 0.6 mm; antenna about as long as head, with four segments, not subsegmented; antennal sensory chaetae of various morphology, including a row of four thickened S-chaetae dorsally and several bifurcate chaetae ventrally on Ant. IV, no apical bulb on Ant. IV; PAO moruliform, large for Oncopoduridae ; eyes absent; labral chaetae with strong papillae, distal labral chaetae thick and trifurcated; tibiotarsus II without thick clavate chaeta; unguis without baso-external tooth; dens with only ordinary chaetae; mucro elongated with one smooth chaeta; scales hyaline, with discontinuous longitudinal ribs.

Etymology

Named after another genus Oncopodura in the same family, preceded by the Greek stem Sin - for China.

Relationships of Sinoncopodura gen. nov.

Sinoncopodura gen. nov. strongly differs from other oncopodurids by the absence of scales, spines or crooks on dens, while the presence of these modified chaetae were one of the most significant familial characters of Oncopoduridae . Dental chaetotaxic patterns are quite different of those of Sinoncopodura gen. nov. and Oncopodura- Harlomillsia ( Bonet 1943; Szeptycki 1977a), and we have not been able to detect homologies between the arrangement of chaetae in Sinoncopodura gen. nov. and that of spines and crooks in the later genera. Besides, the highly modified mandible, labrum and distal labral chaetae as well as moruliform PAO were found exclusive to our new genus. Despite these unique morphological traits, Sinoncopodura gen. nov. is similar to Oncopodura in the types and the arrangement of antennal chaetae, the absence of eyes, the texture of scales and the shape of furcula; while the morphology of the PAO and the absence of a clavate chaeta on the mid tibiotarsus are more alike those of Harlomillsia .

Patterns of tergal chaetotaxy of Oncopoduridae have been studied by Szeptycki (1977b). In Harlomillsia oculata the chaetotaxy is well developed, chaetae on Abd. I and Abd. II arranged in three transversal rows, macrochaetae present on each tergites except on Th. II and bothriotricha absent; whereas in Oncopodura the chaetotaxy is remarkably reduced, only one row of chaetae is present on each of the first two abdominal segments, macrochaetae are absent from Th. II to Abd. II and bothriotricha are present on thoracic tergites and Abd. II. The chaetotaxy of Sinoncopodura gen. nov. resembles that of Harlomillsia oculata in the presence of macrochaetae on each tergite but it has the same reduced general pattern as Oncopodura ; in addition, the differentiation of anterior chaetae on Abd. V is observed in both Sinoncopodura gen. nov. and Oncopodura but not in Harlomillsia .

Morphologically Sinoncopodura gen. nov. is therefore intermediate between the other two genera by several important characters, but overall appears to be more close to Oncopodura .