Ceratophysella brevisensillata Yosii 1961

Ceratophysella brevisensillata Yosii, 1961

Figs 1-9

MATERIAL EXAMINED: 10 paratypes (?) on slides, formerly in alcoholic vial labeled: „ Hypogastrura (Ceratophysella) pseudarmata (Folsom) det. Yoshii, USA (Massachusetts), Arlington 15.XI.1950, leg. Bonet, on rain pools” (MNHG).

REDESCRIPTION: Body length 1-1.3 mm. Color in alcohol grey to dark grey. Eye patches black, anal spines light. Granulation fine and uniform, with 14-22 granules between setae p 1 on abd. V. Dorsal chaetotaxy of B type, macrosetae p 2 on th. II-III set nearly in line with setae p 1, setae m 3 and m 4 on th. II usually present, setae a 2 longer than a 3, setae m 6 absent, setae p 1 and p 2 on abd. IV macro- and microsetae respectively, setae p 3 present (Figs 1-2). Arrangement of setae on head typical for the genus. Differentiation of dorsal setae into micro- and macrosetae distinct. Setae long, pointed, slightly curved and serrated (Fig. 3). Body sensilla (s) p 4 on th. II-III and p 5 on abd. I short, about 1/3-1/2 of microsetae. Body sensilla on abd. II-V and lateral parts of th. II-III long, but shorter than macrosetae (Fig. 3). Microsensilla (ms) on th. II present. Subcoxae I-III with 1, 2, 3 setae respectively.

Ant. IV with simple apical vesicle, subapical organite (or), microsensillum (ms), 7 cylindrical sensilla (2 lateral and 5 dorsal), about 15-20 short curved flattened at tips sensilla in ventral file (Fig. 4). Ant. III-organ with two long (lateral) and two short (internal) curved sensilla. Microsensillum on ant. III present. Eversible sac between ant. III-IV present. Ant. I with 7 setae.

Ocelli 8 + 8. Postantennal organ about twice as large as single ocellus, with four lobes of which the anterior pair larger than the posterior. Accessory boss present (Fig. 5).

Labrum with 5, 5, 4 setae and without apical papillae. 4 prelabrals present. Labium and head of maxilla (Fig. 6) of the C. armata type. Outer lobe with 2 sublobal hairs.

Tibiotarsi I, II, III with 19, 19, 18 setae respectively, tibiotarsal tenent hairs slightly longer than inner edge of claws and pointed. Claws with inner tooth and pair of indistinct lateral teeth. Empodial appendage with broad basal lamella and apical filament reaching inner tooth or slightly beyond (Fig. 9).

Ventral tube with 4 + 4 setae.

Furca well developed (Fig. 8). Dens/mucro ratio = ca. 2. Dens with 7 setae (2-4 inner modified). Mucro boat-like. Retinaculum with 4 + 4 teeth.

Anal spines short, half as long as inner edge of claws III, situated on basal papillae (Figs 2, 7).

REMARKS: The species was originally described from the north-eastern part of the USA. Later it was recorded from several localities within the same region (Christiansen & Bellinger, 1980), from Alaska and Chukotka (Fjellberg, 1985) and Siberia (Babenko et al., 1994). Alaskan and East Palaearctic specimens treated as C. brevisensillata clearly differ from the above redescription of Yosii’s types by having longer anal spines and coarser integument granulation. They could be considered as a separate species if their morphology was homogeneous within the area. Unfortunately it is not so and many important diagnostic characters vary in different parts of the distributional range without forming clear geographical pattern. Thus, inner margin of claw III/anal spine ratio varies in Palaearctic specimens from 1.8: 1 to 0.9: 1, being usually about 1: 1. Yosii’s “a” measure is usually 10-12, but the whole range is 9-16. Chaetom differentiation into macro and microsetae is strong in most Palaearctic regions but specimens from Kemerovo Province and eastern Tuva are characterized by weak differences in seta length with a 2 on th. II almost as long as a 1 and a 3. Intermediary conditions have been also seen. The single available specimen from the Kyrgyz mountains has rather short but strong (almost spine-like) macrosetae. Alaskan and Chukotka specimens have 2 sublobals on maxillary outer lobe and p 3 setae on abd. IV are usually absent. Populations from more western parts of Palaearctic differ by having only 1 sublobal hair and both p 2 and p 3 microsetae present on abd. IV. Nevertheless, two sublobals have been also seen in populations from Buryatia, eastern Tuva, north-eastern Altai and Kyrgyzstan and specimens without p 3 on one or both sides on abd. IV can be found within many studied populations. Just now we prefer to treat all these forms as a single polymorphic species with a wide Siberian-American distributional range being sure that more work and material are needed to clear up their status. However the existing distributional gap (see Fig. 21) between east and west American populations raises some doubts that they are conspecific.