Pseudocrangonyx spangsbergi, Sídorov & Labay & Gontcharov, 2020

Sídorov, Dmitry, Labay, Vjacheslav & Gontcharov, Andrey, 2020, New species and records of the subterranean amphipod genus Pseudocrangonyx Akatsuka and Komai (Crustacea: Pseudocrangonyctidae), representing the northernmost distribution of the group, Journal of Natural History 54 (27 - 28), pp. 1759-1795 : 1762

Pseudocrangonyx spangsbergi sp. nov.

( Figures 2a , 3–6 )

Diagnosis (both sexes)

Slender, medium-sized amphipod of typical pseudocrangonyctid habitus (sexual dimorphism pronounced, i.e. males smaller than females; antenna II short, bearing calceoli; uropod II sexually dimorphic with rami bearing 5 modified spines); eyes absent; body unpigmented (whitish in colour); dorsal surface of body segments smooth, teretial; last mesosomal segment (pereonite VII) and metasomal segments (pleonites I–III) bearing 2 fine facial setae each; urosomal segment I (urosomite I) with 2 facial setae and urosomite II with 2 notched facial spines, ecdysial setae present; interantennal lobe of head short, rounded, inferior antennal sinus somewhat roundish; antenna I about 58% length of body; coxal plates I–IV shallow, sub-rectangular (wider than deep), plates V–VII sub-triangular with broad anterior lobes; posterodistal corners of pleonal plates I–III sub-acute; palp mandible article 3 with 3 B-setae, 10 D-setae and 3 E-setae; molar of mandible well developed; propodus of gnathopod I somewhat larger than that of gnathopod II; carpus of pereopods III–IV with posterior margin armed; pereopod VII about 50% length of body. Uropod I with 1 basofacial spine-seta. Telson with distinct notch. Body length 5.5 mm (♀♀), 4.5 mm (♂♂).

Material examined

Holotype MNHN-IU-2019-3170: ♀ ca. 5.5 mm (oostegites developed, setose), RUSSIA, Sakhalin, Sakhalinskaya Oblast, Tomarinsky District, stream on Spangsberg Mt. , under moss, water temperature 4°C, 47.591214, 142.169675, elevation 512 m, leg. V. S. Labay, 10 July 2008 . Paratypes 11/9-DAS: 4 ♀♀ measuring 5.5 mm each (oostegites developed, setose), 2 ♂♂ 4.5 mm, same data as for holotype.

MATERIAL FOR SEM: ♀ ca . 5.5 mm, same data as for holotype . Deposited in the research collection of V .S. Labay in the Sakhalin Branch of the Russian Research Institute of Fisheries and Oceanography (SakhNIRO), Yuzhno-Sakhalinsk, Russia .

Etymology

Species named ‘ spangsbergi ’ after the Danish-Russian voyager Martin Spangsberg (1697– 1761), member of the Kamchatka expeditions.

Figures

Figure 2. Habitus of examined specimens: (a) Pseudocrangonyx spangsbergi sp. nov., holotype, female, 5.5 mm; (b) Pseudocrangonyx setosus sp. nov., holotype, female, 5.5 mm; (c) Pseudocrangonyx myaochanicus sp. nov., holotype, female, 3.2 mm; (d) Pseudocrangonyx borealis sp. nov., holotype, female, 4.5 mm; (e) Pseudocrangonyx camtschaticus Birstein, 1955, female, 7.5 mm.

Figure 3. Pseudocrangonyx spangsbergi sp. nov., holotype MNHN-IU-2019-3170, female, 5.5 mm: (a) antenna I; (b) antenna II; (c) left mandible; (d) right mandible; (e) upper lip; (f) maxilla I; (g) outer plate of maxilla I; (h) lower lip; (i) maxilla II; (j) maxilliped. Scale bars: 0.2 mm.

Figure 4. Pseudocrangonyx spangsbergi sp. nov., holotype MNHN-IU-2019-3170, female, 5.5 mm: (a) gnathopod I; (b) gnathopod II; (c) pereopod III; (d) pereopod IV; (e) pereopod V; (f) pereopod VI; (g) pereopod VII. Scale bar: 0.2 mm.

Figure 5. Pseudocrangonyx spangsbergi sp. nov., holotype MNHN-IU-2019-3170, female, 5.5 mm: (a) pleopod I; (b) pleopod II; (c) pleopod III; (d) epimera I–III; (e) uropod I; (f) uropod II; (g) uropod III; (h) telson. Scale bars: 0.2 mm.

Figure 6. Pseudocrangonyx spangsbergi sp. nov., paratype 11/9-DAS, male, 4.5 mm: (a) antenna II; (b) gnathopod I; (c) gnathopod II; (d) uropod II; (e) telson. Scale bars: 0.2 mm.