Aggressopygus, Potapov & Babenko, 2014

Potapov, Mikhail & Babenko, Anatoly, 2014, About some unusual Asiatic taxa of Isotomidae (Collembola), Journal of Natural History (J. Nat. Hist.) 48 (29 - 30), pp. 1835-1851 : 1841-1842

Aggressopygus gen. nov.

Type species: Aggressopygus sibiricus sp. nov.

Diagnosis

Blind Anurophorinae of ‘ Cryptopygus complex’ with simple postantennal organ, sensilla situated in p-row of setae, and well-developed foil setae.

Description

Without pigment and eyes, Abd.V and VI fused. With primary granulation only. Maxillary palp bifurcate, with 4 sublobal hairs. Labium as common for the family. Maxillary head without considerable modifications. PAO simple. Tergal sensilla on abdomen situated in p-row of chaetae with their number 4,3/2,2,2,3,5. Sensilla of Abd.V form the ‘3 + 1 + 1’ pattern (for the terminology see Potapov and Greenslade 2010). Body macrochaetae well differentiated. Tenaculum with 4 + 4 teeth. Furca slender, manubrium with a few pairs of chaetae on anterior side, dens with crenulation, mucro bidentate.

Representatives

Aggressopygus sibiricus sp. nov., Aggressopygus armatus sp. nov.

Remarks

Because of the fusion of two last abdominal segments, the new genus belongs to the ‘ Cryptopygus complex’ as defined by Potapov et al. (2013). Aggressopygus gen. nov. has 3 sensilla on each side of Abd.IV and 5 + 5 sensilla on Abd.V, a feature shared with the most genera of the complex: Cryptopygus Willem s.str, Hemisotoma Bagnall , Mucrosomia Bagnall and others. In its general appearance, specifically the shape of the body, the absence of pigmentation and ommatidia, and moderately short and slender furca, two species of Aggressopygus gen. nov. appear as do many other unrelated representatives of the ‘ Cryptopygus complex’. For instance, Proisotomodes debilis (Cassagnau) , several European species of Cryptopygus (С. exilis (Gisin), C. scapelliferus (Gisin) , C. albaredai (Selga) , C. delamarei (Poinsot)) , species of the genera Pauropygus Potapov, Gao et Deharveng , Isotominella Delamare Deboutteville , and Mucrosomia Bagnall are also characterized by the same set of characters. The new genus is even more similar to a few genera with a posterior position of sensilla which were combined in an identification key by Potapov et al. (2013). Among these genera, Appendisotoma Stach is morphologically very different to Aggressopygus gen. nov. because of its particular furca and weakly differentiated sensillary chaetotaxy. Other genera with a posterior position of sensilla are probably closer to the new genus, which especially resembles Micrisotoma Bellinger because of the well-developed foil setae (absent in other genera of the group). Several characters of lower taxonomic value, e.g., the shape of furca, specific posterior chaetotaxy of ventral tube, arrangement of postlabial chaetae, also indicate the relationship between the Micrisotoma and Aggressopygus gen. nov. The complex PAO, a unique apomorphy of Micrisotoma , was not present in the new genus and so distinguishes the two genera. The new genus also differs having conical foil setae (vs. cylindrical) and lacks several peculiar characters given below in the redescription of M. achromata .

Etymology

The suffix (pygus) reflects the membership of ‘ Cryptopygus complex’, the prefix (aggresso) points to somewhat aggressive appearance of the animal due to welldeveloped foil setae on the end of abdomen and a pair of strong teeth on labrum in the type species of the genus ( A. sibiricus sp. nov.)