Sahacanthella saoriae Nakamori & Potapov, 2017

Babenko, Anatoly, 2017, New or little-known taxa of Anurophorinae (Collembola) with anal spines from East Asia with notes on DNA barcode, Zootaxa 4318 (2), pp. 312-324 : 314-317

Sahacanthella saoriae Nakamori & Potapov , sp.nov.

Figs 2, 3, 5–8

Syn: Sahacanthella kele: Suma, 2008

Sahacanthella cf. kele: Niijima & Hasegawa, 2011

Material. Holotype: adult female on slide. Japan, Hokkaido Island , Shiretoko Peninsula , trail to Rausu Mountain, mosses and lichen on open rock, 19.viii.2016, ca. 400 m alt., N44.10°, E145.10°, coll. M. Potapov, N. Kuznetsova. Kept in Tottori Prefectural Museum (voucher number TRPM-AAr-0000705).

Paratypes: 10 specimens from the same place (5 kept in Tottori Prefectural Museum (propylene glycol, voucher numbers TRPM-AAr-0000686–TRPM-AAr-0000690), 5—in Moscow State Pedagogical University, slides with Gisin's medium). Two sequenced specimens from same area, mixed forest, lichens on rocks and trees, ca. 600 m alt. (voucher numbers TRPM-AAr-0000684 and TRPM-AAr-0000685). Kept in Tottori Prefectural Museum.

Description. Size of adult females 0.9–1.1 mm (adult males not seen). Color greyish-blue. Body moderately elongated ( Fig. 2 ). Cuticular polygons roundish and small, smaller than diameter of microseta bases. Smooth fields absent, polygons well developed on medial conical protuberance of Abd. IV ( Fig. 7 ). 8+8 ommatidia, G and H smaller ( Fig. 6 ). PAO narrowly elliptical, with weak constriction, 2.3–3.5 times longer than nearest ocellus and shorter than Ant. I width (0.7–0.8). Maxillary outer lobe with bifurcate palp and 4 sublobal hairs. Labral formula as 4/554. Labium with all five papillae and complete set of guards (16), 3 and 4 setae on proximal and basomedian fields of labium, respectively. Ventral side of head with 4+4 postlabial setae. Ant. I with 11 setae, 2 bms, dorsal and ventral, and 2 latero-ventral s. Ant. II with 3 bms and one s. Ant. III with one bms and with 5 (rarely 6) s, inner pair of s -setae of AO as long as outer ( Fig. 10 ). Ant. 4 with small subapical organite and weakly differentiated s -setae. Apical papillae undeveloped.

Arrangement of ms -, s -setae and macrosetae shown on Fig. 2 . S -setae thin and short. Sensillary formula as common for the group: 33/22224 (s), 11/111 (ms). Medial s -setae on Abd. I–III set behind Mdl-macrosetae. Microsetae of normal size, dorsal axial chaetom of Th. II–Abd. IV as 8(7–9),6–7/5,5,5,7–8 (for one side).

Macrochaetotaxy 1,1/1,1,1(2): only Ml-macrosetae well developed. Mdl-macrosetae on Abd. I–II rudimentary but erect and recognizable, those on Abd. III stronger. Medial microsetae on Abd. V anterior to nearest macrosetae, Md -macroseta of Abd. IV 1.2–1.6 as long as p l-seta ( Fig. 8 ). Thoracic sternites without setae.

Coxa of first pair of legs with seta. Claw with inner tooth ( Fig. 9 ), unguiculus half as long as inner side of claw. Dorsal tenent hairs 1,2,2, slightly clavate and short, 1.2–1.4 times longer than inner side of claw on Leg 3, second clavate hair on hind leg shorter. Ti. 1–2 without additional setae (21 setae on each), Ti. 3 with 25–28 setae ( Fig. 9 ). Ventral tube with 4–5+4–5 laterodistal and 7–8 postero-basal setae. Tenaculum with 4+4 teeth and one seta. Furca present, manubrium with a pair of anterior setae, posterior side with 10–12+10–12 setae on main part and 3+3 on latero-basal lobes ( Fig. 5 ). Dens with 5–6 (rarely 4) posterior and 2 anterior setae ( Figs 3, 5 ). Mucro with two teeth. Ratio manubrium: dens: mucro as 4.7–5.5: 2.9–3.4: 1.

Discussion. A single previously known species of the genus, i.e. Sahacanthella kele Potapov & Stebaeva , was described in 1993 from alpine tundra belt in the upper reaches of Kele River (NE Siberia) and never recorded afterwards. The new species from Hokkaido clearly differs from the Siberian congener by the presence of a setal pair on anterior side of manubrium (absent in S. kele , Fig. 4 ). Apart from this, S. saoriae sp. nov. shows less developed set of macrosetae ( S. kele has 2,2,2 distinct macrosetae on Abd. I–III, cf. Fig 1 and Fig. 2 ), usually has more setae on posterior side of dens (4–6 vs. 3–5) and claw with inner tooth present (absent in S. kele ). In the original description of S. kele it was wrongly stated that the latter possesses 2 prelabral setae whereas both species normally have labral set as 4/554.

The new species was previously recorded under different names. Suma (1997) listed ' Anurophorinae sp.' among species from Akan National Park (central part of eastern Hokkaido) without any remarks on its taxonomical position. Afterwards, the same author ( Suma 2008) redescribed and illustrated this species under the name Sahacanthella kele from Shari Mountain (more coastal part of the same area). It was mentioned that this was the second record of the species from Japan while the first one was by Suma (1997). Several peculiarities of Japanese specimens versus the original description were given: presence of inner tooth on hind claw; 8+8 setae on posterior side of manubrium; 6+6 setae on posterior side of dens; similar size of teeth of mucro. Niijima and Hasegawa (2011) referred specimens of Suma (2008) as Sahacanthella cf. kele and under the same name it was included in the Pictorial Keys to Soil Animals of Japan ( Aoki 2015).

Distribution and ecology. Known from three localities in eastern part of Hokkaido and seems to prefer moss and lichen cover on various exposed objects where it can be very abundant.

Etymology. The new species is dedicated to our colleague Saori Fujii (Vrije University of Amsterdam) who is recently working on Collembola of Shiretoko Peninsula.

Figures

FIGURES 1 – 5. Sahacanthella kele (1, 4) and S. saoriae sp. nov. (2, 3, 5): 1 – 2, chaetotaxy of body tergites; 3 – 4, distal part of furca in individuals with the least number of setae on dens, variation (3) shown, lateral view; 5, furca, posterior view. Mdl, Ml — dorso-lateral and lateral macroseta, s, ms — s - setae and ms - seta.

FIGURES 6 – 10. Sahacanthella saoriae sp. nov.: 6, PAO and ocelli; 7, medial conical protuberance, lateral view; 8, Abd. IV – VI; 9, distal part of tibiotarsus 3; 10, Ant. 3, lateral view, variability shown. Md — dorsal macroseta, s — s - seta.