Pseudocrangonyx holsingeri Sidorov & Gontcharov, sp. nov.
Creators: name: Sidorov, Dmitry A.
name: Gontcharov, Andrey A.
Publisher: name: Zenodo
Year: 2013
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Pseudocrangonyctidae
Pseudocrangonyx
Pseudocrangonyx holsingeri

description: Pseudocrangonyx holsingeri Sidorov & Gontcharov, sp. nov.   
(Figs 3 B, 33–63)  
 Diagnosis. Small-sized species with marked secondary sexual dimorphism. Dorsal surface of body segments smooth (Fig. 3 B), teretial, bearing detached fine setae. Eyes absent. Body unpigmented. Interantennal lobe of the head (Fig. 33) rounded, slightly tapered; inferior antennal sinus moderate. Antenna 1 about 30% length of body. Antenna 2 with calceoli in females. Palp mandible article 3 with 2 B-seta, 7 D-setae and 4 E-setae. Ventral surface of pereonites 2–7 with sternal humps (blisters). Pereopod 6 largest. Urosome without “ecdysial setae”. Uropod 1 with 2 basofacial seta. Inner ramus of male uropod 2 without serrate setae. Telson emarginated. Body length 2.8– 5.5 mm (females), 4.0– 4.2 mm (males).   
 Type locality. Russia, Far East, Steklajnuha River (43º21.027' N 132º27.723' E), subterranean waters (hyporea), 34 m above sea level.   
 Material examined. Holotype: female (5.5 mm, oostegites developed, non-setose), X38654 /Cr-1470-FEFU, Russia, Primory Territory, the Steklajnuha River (43º21.027' N 132º27.723' E), 12 Jun 2010, coll. D.A. Sidorov & K.A. Semenchenko. Paratypes: 11/7sd-IBSS, 3x females (3.5 mm, oostegites developed, non-setose), 3x females (2.8 mm, oostegites developed, non-setose), 2 males (4.2 mm, 4.0 mm); paratypes with same data as holotype.   
 Etymology. Species named in honor of famous zoologist John R. Holsinger (Old Dominion University, Norfolk, VA, USA) for his outstanding contribution to the systematics of subterranean crustaceans.   
 Description. Female (5.5 mm), X38654 /Cr-1470-FEFU. Head. Antenna 1 (Fig. 34) about 30% length of body, 74% longer than antenna 2; peduncular articles 1–3 in length ratio 1:0.8:0.5; primary flagellum with 16 articles; aesthetascs present. Antenna 2 (Fig. 35), peduncular articles 4 and 5 in lengths ratio 1:0.9; flagellum with 6 articles; calceoli present. Left mandible (Fig. 47) incisor 5-dentate; lacinia mobilis 5-dentate; setal row with 5 serrate setae. Right mandible (Fig. 48) incisor 5-dentate; lacinia mobilis trifurcate. Molar process small, triturative, with short accessory seta. Palp mandible article 2 slightly shorter than article 3; article 3 with 2 B-seta, 7 D-setae and 4 Esetae. Lower lip (Fig. 43), inner lobes absent; mandibular process indistinct (roundish). Maxilla 1 (Fig. 45), inner plate with 4 plumose setae; outer plate with 7 serrate setae; palp article 2 about 2.0× longer than article 1 bearing 2 robust setae on apex. Maxilla 2 (Fig. 46), inner plate with 4 plumose setae. Maxilliped (Fig. 49) inner plate with 2 apical and 3 sub-apical setae; outer plate with a row of 3 medial robust serrate setae, 9 naked setae and 3 apical stiff setae. Lateralia (Fig. 50) with 8 strong pectinate setae. Pereon. Coxal plates 1–4 (Figs 41, 42, 51, 52) shallow, subrectangular but plate 2 somewhat roundish. Gnathopod 1 (Fig. 41), carpus 0.3× as long as propodus, rastellate setae absent; propodus palm oblique, defining angle indistinct, palm with cutting margin crenulated, palm with 20 distally notched robust setae in two rows and 6 distally notched robust setae near defining angle; dactylus, inner margin dentate. Gnathopod 2 (Fig. 42), carpus 0.5× as long as propodus, with 3 rastellate setae; propodus palm oblique, defining angle indistinct, palm with cutting margin crenulated, palm with 20 distally notched robust setae in 2 rows and 4 distally notched robust setae near defining angle; dactylus similar to that of gnathopod 1. Pereopod 6 longer than pereopod 7. Pereopods 3 and 4 (Fig. 52) with a row of long setae on posterior margin; carpus as long as propodus. Coxal gill 7 absent. Ventral surface of pereonites 2–7 bearing sternal humps (blisters). Pleon. Epimera 1–3 (Fig. 40): posterior corners obtuse, armed with 1 stiff seta each; ventral margin of plate 1 without setae, plate 2 with 2 short setae and plate 3 with 3 short setae. Pleopods 1–3 (Fig. 56), peduncular articles with 2 coupling setae (retinaculae). Urosome (Fig. 3 B): urosomite 1, “ecdysial setae” absent. Uropod 1 (Fig. 36): peduncle with 7 setae on outer margin, 3 long seta on inner margin and with 2 basofacial setae; outer ramus 0.7× as long as inner ramus, about 70% length of peduncle; inner ramus armed with 6 setae on both margins and with 2 long setae on ventral face; outer margin of outer ramus armed; rami with 5–6 setae on apices, one of them very long. Uropod 2 (Fig. 37): peduncle with 4 setae on outer margin and 3 setae on inner margin; outer ramus 0.7× as long as inner ramus; inner ramus slightly longer than peduncle, armed with setae on both margins; outer margin of outer ramus armed; rami with 5 setae on apices, one or two of them longer. Uropod 3 (Fig. 38): uniramous; peduncle with 2 sets of stiff setae on distal margins; proximal article of outer ramus 2.5× as long as peduncle, bearing 6 sets of setae on inner and outer margins; terminal article 0.2× as long as proximal article, with 3 setae on apex. Telson (Fig. 39): 1.5× as long as uropod 3 peduncle; 0.3× longer than broad, emarginated; tips of lobes with 2 strong setae apically, one of them long. Oostegites 2–5 on gnathopod 2 and pereopods 3–5 (Figs 42, 52) sub-linear, unmatured without marginal setae.   
 Male (4.2 mm, apparently immature), 11/7sd-IBSS, sexually dimorphic characters. Head. Antenna 2 (Fig. 57): peduncular articles 4 and 5 poorly setose; flagellum with 5 articles; calceoli absent. Pereon. Gnathopod 1 (Fig. 58): carpus with 1 rastellate seta; palm with 3 distally notched robust setae in 2 rows and 4 distally notched robust setae near defining angle. Gnathopod 2 (Fig. 59): propodus palm sub-transverse, defining angle distinct, palm with 3 distally notched robust setae in 2 rows and 3 distally notched robust setae near defining angle. Pereopods 3 and 4 with a row of long setae on posterior margin; carpus as long as propodus. Pleon. Uropod 1 (Fig. 60): peduncle with 1 basofacial seta. Uropod 2 (Fig. 61): peduncle weakly setose; rami without serrate robust setae. Uropod 3 (Fig. 62): proximal article of outer ramus bearing 4 sets of setae on inner and outer margins. Telson (Fig. 63): 2.0× as long as uropod 3 peduncle; 0.2× longer than broad.   
 Variability. Slight variation in armature of outer rami of uropods 1 and 2 was observed, as well as a slightly different degree of telson emargination.   
 Taxonomic comments. P. holsingeri, sp. nov. mostly resembles P. levanidovi and P. shikokunis by the shape and structure of gnathopods 1–2. The presence of calceoli on female antenna 2 creates an affinity to P. shikokunis. The shape and structure of uropod 3 with 4–6 sets of setae on the proximal article of outer ramus and short terminal article is similar in P. camtschaticus Birstein, 1855 and in P. asiaticus sensu Ueno, 1966. The distinct and narrow mandibular process of lower lip and expanded palmar margin of gnathopod 2 in male are unique features distinguishing P. holsingeri, sp. nov. from all known species of the genus.   
 Distribution and ecology. P. holsingeri, sp. nov. known only from type locality. Stygobiont crustaceans Mackinia sp., Acanthocyclops sp. and Diacyclops sp. and several interstitial species of water mites were collected from this same locality.
description: Published as part of Sidorov, Dmitry A. & Gontcharov, Andrey A., 2013, Studies on subterranean amphipod crustaceans of Primory, Russia. Part 1. Three new species of the genus Pseudocrangonyx from springs and other groundwater habitats in far eastern Russia, pp. 547-567 in Zootaxa 3693 (4) on pages 557-561, DOI: 10.11646/zootaxa.3693.4.8, http://zenodo.org/record/215733