Pseudocrangonyx borealis Sídorov &amp; Labay &amp; Gontcharov 2020, sp. nov.
Creators: name: Sídorov, Dmitry
name: Labay, Vjacheslav
name: Gontcharov, Andrey
Publisher: name: Zenodo
Year: 2020
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Pseudocrangonyctidae
Pseudocrangonyx
Pseudocrangonyx borealis

description: <i>Pseudocrangonyx borealis</i> sp. nov. (Figures 2d, 14–17) <i>Diagnosis (female)</i> Slender, small-sized amphipod of typical pseudocrangonyctid habitus (sexual dimorphism unknown); 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; urosomites I– II with 2 facial setae, ecdysial setae absent; interantennal lobe of head short, rounded, inferior antennal sinus roundish; antenna I about 50% length of body; coxal plates I– IV shallow, sub-rectangular (wider than deep), plates V – VII sub-triangular with moderate anterior lobes; posterodistal corners of pleonal plates I– III broadly roundish; palp mandible article 3 with 2 B-setae, 8 D-setae and 3 E-setae; molar of mandible well developed; propodus of gnathopod I much larger than that of gnathopod II; carpus of pereopods III – IV with posterior margin unarmed; pereopod V distinctly shorter; pereopods VI and VII equal, about 45% length of body. Uropod I with 1 basofacial spine-seta. Telson with vestigial notch. Body length 4.5 mm (♀). <i>Material examined</i> Holotype MNHN-IU-2019-3173: ♀ ca. 4.5 mm (oostegites developed, non-setose), RUSSIA, Magadanskaya Oblast, Khasynsky District, basin of the Ola River, Neorchan River, hyporhea, 60.462461, 151.471181, elevation 555 m, leg. E. V. Khamenkova, 10 June 2013. <i>Etymology</i> Species named ' <i>borealis</i> ' (Latin), an adjective that refers to the northern distribution of this species. Gender masculine. <i>Description</i> Female (body 4.5 mm long), MNHN-IU-2019-3173. <b>Head</b> (Figures 2d, 14a–i). <i>Antenna I</i> about 33% longer than antenna II; peduncular articles 1–3 in length ratio 1:0.5:0.3; primary flagellum with 13 articles; aesthetascs present. <i>Antenna II</i> peduncular articles 4 and 5 in length ratio 0.9:1; flagellum with 6 articles; calceoli absent. <i>Left mandible</i> incisor 5-dentate; lacinia mobilis 5-dentate; setal row with 3 serrate setae; palp mandible article 3 is 15% longer than article 2; article 3 with 2 B-setae, 8 D-setae and 3 E-setae. <i>Right mandible</i> incisor 5-dentate; lacinia mobilis bifurcate, with numerous small teeth; molar process triturative, with short accessory seta. <i>Lower lip</i> inner lobes absent; mandibular process brief, roundish. <i>Upper lip</i> without peculiarities. <i>Maxilla I</i> inner plate with 3 plumose setae; outer plate with 7 serrate spines; palp article 2 about 2.2× longer than article 1, bearing 3 spines on apex. <i>Maxilla II</i> inner plate with 3 plumose setae in oblique row. <i>Maxilliped</i> inner plate with 2 simple spines and 3 long simple setae apically; outer plate with a row of long simple setae on lateral and apical margins. <b>Pereion</b> (Figures 2d, 15a, b, 16a–e). <i>Gnathopod I</i> carpus (article 5) 0.6× as long as propodus, rastellate setae absent; palm oblique, defining angle indistinct, palm with cutting margin crenulated, palm with 13 distally notched robust spines in two rows; dactylus, inner margin dentate, with 1 seta along outer margin. <i>Gnathopod II</i> carpus (article 5) slightly longer than propodus, rastellate setae absent; propodus palm bevelled, defining angle distinct, palm with cutting margin crenulated, palm with 5 distally notched robust setae in two rows and 7 distally notched robust setae near defining angle; dactylus similar to that of gnathopod I. <i>Pereopods III</i> and <i>IV</i> sub-similar; bases sub-linear, with a row of long and short setae on posterior margin; carpus (article 5) as long as propodus, posterior margin naked. <i>Pereopod VI</i> as long as <i>pereopod VII</i>. Ventral surface of pereonites II–VII bearing sternal humps (blisters). <i>Coxal gills II–VI</i> stalked and saccular. <i>Oostegites II–V</i> on gnathopod II and pereopods III–V developed, without marginal setae. <b>Pleon</b> (Figures 2d, 17a–h). <i>Epimera I–III (pleonal plates)</i> posterior corners broadly roundish, armed with 1 stiff seta each; ventral margin of plate I without setae, plates II and III with 1 seta each. <i>Pleopods I–III</i> peduncular articles with 2 coupling setae (retinacles). <i>Uropod I</i> peduncle with 5 spines on outer margin, 3 spines on inner margin, 1 basofacial spine-seta; outer ramus 0.6× as long as inner ramus, about 50% length of peduncle; inner ramus armed with 6 spines on each margin and with 4 long thin setae on ventral face; outer ramus unarmed; rami with 5 spines on apices, one or two of them very long. <i>Uropod II</i> peduncle with 2 spines on outer margin and 3 spines on inner margin; outer ramus 0.8× as long as inner ramus; inner ramus as long as peduncle, armed with spines on both margins; outer margin of outer ramus with 2 spines; rami with 5 spines on apices, one or two of them long. <i>Uropod III</i> uniramous; peduncle with 1 spine and 1 seta on distal margin; proximal article of outer ramus 3.0× as long as peduncle, bearing 4 sets of spines on inner and outer margins; terminal article 0.2× as long as proximal article, with 3 setae on apex. <i>Telson</i> 1.4× as long as uropod III peduncle; 0.5× longer than broad, apical margin with vestigial notch; tips of lobes with 1 long spine apically each.
description: Published as part of <i>Sídorov, Dmitry, Labay, Vjacheslav &amp; 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, pp. 1759-1795 in Journal of Natural History 54 (27 - 28)</i> on pages 1778-1779, DOI: 10.1080/00222933.2020.1820092, http://zenodo.org/record/5030637