Schaefferia bermani Babenko 2019, sp. nov.

Schaefferia bermani sp. nov.

Figs 1–2, 5–8, 11

Diagnosis. Species of the genus Schaefferia having 5+5 subequal ocelli, a complete set of labial papillae, short but complete furca with 4–5 dental chaetae and only 2+2 microchaetae along midline of Abd.4.

Type material. Holotype, female, Russia, North-East, Chukchi Peninsula, Lavrentiya [N 65.58°, E 171.00°], Salix spp. shrubs, pit-traps, July 2013. O. Makarova & A. Babenko leg.

Paratypes (all from same location), 2 males, zoogenic meadow on shore slope, 05.07.2013; 15 females and 7 males, organic substrata from Ochotona hyperborea nest, 07.07.2013; 5 females, Lemmus trimucronatus colony, 30.07.2013; 3 females, 1 male and 1 juvenile, peatland, 30.07.2013; 4 males and 1 female, lichen tundra on hill top, 07.07.2013; 3 females, 1 male and 1 juvenile, wet slope with Petasites sp., 16.07.2013; 4 females and 5 males, Benneta Island, ornithogenic substrata, 26.07.2013. O. Makarova & A. Babenko leg. Types deposited in MSPU.

Additional material: more than 500 specimens (alcohol) from different sites within the same area.

Description. Length of males 0.9–1.3 mm, females 1.0– 1.5 mm, holotype— 1.08 mm. Colour live light, brownish-grey and spotted, ventrally almost uncoloured. Granulation rather uniform, slightly coarser only on abdominal tip, with 10–14 granules between chaetae p 1 on Abd.5. Ant.4 with simple apical bulb and usual set of differentiated sensory chaetae (5 dorsal [S 0– S 4] and 2 external [S 7 and S 8]), subapical organite and microsensillum present as normal (see D’Haese 2003). Ventral file on Ant.4 poorly developed with about 8–12 short erect chaetae around curved sensillum. Eversible integumental sac between Ant.3 and Ant.4 invisible. Ant.3 organ typical, with all usual sensorial elements: two outer and two inner sensilla, lateral microsensillum also present. Ant.1–2 with 7 and 13 chaetae, respectively, dorsal ones clearly coarser and thicker. Head with 5 + 5 practically equal dark ocelli. PAO typical, with four lobes, anterior pair much longer, accessory boss usually developed. Labrum typical for genus with 4/554 chaetae. Labium with all normal papillae (A–E), 14 guards (a 1, b 1, b 2, d 2 and e 2 shorter and set on low papillae, a 1 thick and blunt, others pointed) and six proximal chaetae, lateral process rudimentary (Figs 2 and 2a). Basomedial field of labium (submentum) with four chaetae, basolateral field (mentum) with 5 chaetae as normal. Ventral side of head with 3+3 postlabial chaetae along ventral line. Maxillary head unmodified, of general denticulata - type (Fig. 5), outer lobe simple with one sublobal hair typical for genus.

Dorsal chaetotaxy generally of A - type as in Fig. 1. Dorsal chaetae clearly differentiated into macro- and microchaetae. Dorsal macrochaetae (and some midtergal microchaetae) almost of same thickness over entire length due to hyaline “cover”. Most of dorsal chaetae smooth but few on abdominal tip (Abd.5–6) finely serrated. Lateral microsensillum on Th.2 present as usual. Main characteristics: Abd.1–3 with a 2’ (with 4+4 axial microchaetae between p 2-macrochaetae) but only one m 3-chaeta present on all specimens checked. Only 2+2 midtergal microchaetae present on Abd.4, i.e. chaetae a 1 always absent. Chaetotaxic variability low; only m 3-chaeta in dorsolateral group on Th.2 terga frequently and usually asymmetrically absent although always present on Th.3.

Legs 1–3 chaetotaxy as follows: upper subcoxae—1, 3, 3 (among them one macrochaeta on each subcoxa); lower subcoxae—0, 3, 3; coxae—3, 7, 8; trochanters—7, 7, 7; femora—(13)14, 13, 12(13); tibiotarsi—19, 19, 18 chaetae, respectively. Tenent tibiotarsal chaetae not differentiated, chaeta A 1 pointed, only slightly longer than other chaetae of A -whorl and about as long as 1.0–1.1 of inner unguis edge. Unguis slender with strong inner tooth and a pair of lateral ones; unguiculus with clear basal lamella, its apical filament reaching inner tooth on unguis (Fig. 8). Ventral tube with 4+4 distal chaetae. Retinaculum with 3 + 3, rarely 3 + 4 teeth. Furca short (Figs 6–7), mucro with distinguishable lateral lamella of rather variable shape; dens usually with 4–5 posterior chaetae (whole range seen - 3–5), one of which about as long as dens+mucro (ratio 0.9–1.0: 1). Mucro + dens slightly longer than inner edge of hind unguis (1.1–1.2). Anal spines curved, rather long and on high cuticular papillae.

Etymology. The new species is named after an outstanding northern ecologist and ecophisiologist, Professor D.I. Berman, thanks to whose activity our team could spend a fruitful field season on Chukotka.

Affinities. This species was recorded by Babenko (2017) as Schaefferia sp. aff. czernovi noting that it “ differs from S. czernovi in the presence of only 2 + 2 axial setae on Abd.4, and from S. cheoha Wray 1963, in the number of ocelli and the presence of setae of m-row on Abd.1–3”. It is similar to the former species having almost identical diagnostic characters and inhabiting analogous communities in the northeastern Palaearctic. However the chaetotaxic pattern noted above does not permit S. bermani sp. nov. to be unambiguously distinguished from S. czernovi, because a frequent absence of a 1-chaetae at least on one side of Abd.4 (Fig. 9) is also characteristic of the available material of S. czernovi (see below). Actually these species reliably differ only in the labial palpi (cf. Figs 2 and 3), as true S. czernovi has no labial papilla C (Fjellberg 1999).

Thibaud et al. (2004) recorded five other Schaefferia species with 5+5 ocelli in the Palaearctic. Four of them, S. canigouensis Deharveng et Thibaud, 1980, S. decemoculata (Stach, 1939), S. bidentata (Cassagnau, 1953) and S. maxima Deharveng et Thibaud, 1980, are known only from Europe and S. quinqueoculata (Yosii, 1956) is said to be widespread in Asia (from Japan to the Eastern Caucasus). Unlike S. bermani sp. nov., all these species are characterised by the presence of 3+3 axial microchaetae on Abd.4. The wide distributional range of S. quinqueoculata in Thibaud et al. (2004) is based on its synonymy with northern S. czernovi and Typhlogastrura shtanchaevae, described from the Caucasus. This synonymy appears to be dubious (Babenko & Fjellberg 2006, p. 25).

Two similar congeners, however having 6+6 ocelli, are known from more southern regions on the other side of the Bering Strait, namely S. duodecimocellata Bonet, 1945 and S. cheoha. The former was described from mountainous region of the Pacific coast of Mexico based on a single subadult specimen. Later it was definitively recorded only from Alaska (Alaska Range and Juneau Mountains, 1.000 m) and Washington (Mt. Rainier, 2.500 m) by Fjellberg (1985). Nevertheless, Thibaud et al. (2004) synonymised S. duodecimocellata with European S. vandalica and considered it as a part of the Palaearctic fauna. In my view, such formal synonymisation of geographically separated forms without morphological justification is hardly reasonable. I have checked specimens from the Northern Ossetia on which my redescription of S. vandalica was based (Babenko et al. 1994) and found that the labial palp of this form is identical to that of S. czernovi, i.e. papilla C is absent, whereas specimens of S. duodecimocellata from North America have a complete labial palp (A. Fjellberg, pers. com.). The identification of specimens from the Northern Caucasus as S. vandalica described from Spain is also questionable (Jordana et al. 2012).

Schaefferia cheoha recently redescribed based on Wray’s types from Tennessee (Bernard 2015) can be reliably compared with S. bermani sp. nov. Apart from different number of ocelli, S. cheoha differs from S. bermani sp. nov. in many firm chaetotic characters: weak differentiation of dorsal chaetae on head— all dorsal head setae… of similar length except setae p4 and g4 longer than other setae (vs clear differentiation in S. bermani sp. nov.), chaetae p 3 on Th.2–3 as microchaetae significantly shorter than macrochaetae p 2 (vs subequal in S. bermani sp. nov.), the absence of chaetae a 2’ and chaetae of m -row on Abd.1–3 (vs chaetae a 2’ and m 3 always present in S. bermani sp. nov.), only two rows of chaetae present on Abd.4 (vs three rows in dorsolateral part of this tergum in S. bermani sp. nov.), Abd.2–4 without chaetae p 3 and chaetae p 2 are absent on Abd.5 (both chaetae present in S. bermani sp. nov.). There are also other differences, for instance, two blunt labial guards a 1 and b 1 (vs only one, whereas b 1 is pointed in S. bermani sp. nov.) and the absence of lateral teeth on unguis (always present in S. bermani sp. nov.).

Distribution and ecology. Schaefferia bermani sp. nov. is known only from the region of the type locality (Fig. 11) where it inhabits a wide range of different plant communities clearly preferring zoogenically enriched substrata.