Diastylopsis bicarina Gerken, 2015, n. sp.
Creators: name: Gerken, Sarah
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Cumacea
Diastylidae
Diastylopsis
Diastylopsis bicarina

description: Diastylopsis bicarina n. sp.
(Figs. 28–29)
Material examined. Holotype: preparatory female, NIWA 0 93209, TAN0705/251, 42.9958°S, 178.9957°E – 42.9910°S, 179.0052°E, 520–530 m, 24 April 2007. Paratype: preparatory female (dissected), NIWA 0 93181, TAN0707/29, 38.6177°S, 168.9428°E – 38.6258°S, 168.9490°E, 480–482 m, 29 May 2007. Non-type material: 1 specimen, NIWA 13724, O 353B, 34.9000°S, 173.2967°E, 0 m; 1 specimen, NIWA 0 94880, TAN0705/276, 42.6213°S, 175.9225°E – 42.6203°S, 175.9335°E, 1194–1199 m, 26 April 2007; 1 specimen, NIWA 0 94969, E417, 45.2000°S, 171.8267 E, 860 m, 13 October 1965; 2 specimens, NIWA 0 94970, TAN0707/29, 38.6177°S, 168.9428°E – 38.6258°S, 168.9490°E, 480–482 m, 29 May 2007; 3 specimens, NIWA 0 94971, TAN0705/178, 43.5212°S, 178.6203°W – 43.5228°S, 178.6315°W, 424–425 m, 18 April 2007; 4 specimens, NIWA 0 94972, TAN0705/255, 43.5300°S, 178.5048°E – 43.5363°S, 178.5118°E, 346 m, 24 April 2007; 1 specimen, NIWA 0 94973, TAN0705/65, 44.0162°S, 178.5210°E – 44.0143°S, 178.5175°E, 769–771 m, 7 April 2007; 1 specimen, NIWA 0 94974, TAN0705/49, 44.4862°S, 177.1413°E – 44.4841°S, 177.1416°E, 1235–1239 m, 6 April 2007.
Diagnosis. Female and subadult male. Carapace with 2 oblique entire parallel ridges, smooth posterior of oblique ridges. Eyelobe with lenses. Pereonites 3–4 not fused. Pereopods 3–4 with rudimentary exopods in female. Telson extending to end of uropod peduncle, with 3 pairs lateral setae, 2 terminal setae.
Adult male. Unknown.
Etymology. The combination of the Latin bi meaning two, and carina meaning ridge or keel, in reference to the two parallel ridges on the carapace.
Description. Preparatory female holotype 3.9 mm, preparatory female paratype 4.25 mm. Body (Figs. 28 A– B). Carapace dorsal outline rugose anterior of oblique ridges. Pleon unornamented.
Antennule (Fig. 28 C) article 1 longest, wide, with 1 simple and 2 plumose setae; articles 2 and 3 narrow. Main flagellum of 3 articles, with 2 aesthetascs; accessory flagellum narrow, of 1 article, not as long as main flagellum article 1, with few simple setae.
Antenna (Fig. 28 C) of 4 articles, article 1 largest, with simple and plumose setae.
Mandibles (Fig. 28 D) navicular, lacinia mobilis wide, with 3 cusps, with row of 9 microserrate setae medially.
Maxillule (Fig. 28 E) with 2 endites; palp with 2 microserrate setae.
Maxilla (Fig. 28 F) with 3 endites; broad endite medial row of setae simple; narrow endites long, with microserrate setae.
Maxilliped 1 (Fig. 28 G) carpus without beak setae, with simple setae.
Maxilliped 2 (Fig. 28 H) basis margins serrate.
Maxilliped 3 (Fig. 28 I) 100:10:8:10:19:13; basis produced widely at distolateral corner with 8 plumose setae, medial margin with spines distally and pappose setae.
Pereopod 1 (Fig. 30 A) 100:13:15:62:55:50; very long; basis with many plumose setae; ischium, merus carpus unarmed; propodus with few simple setae; dactylus with simple setae, terminal setae long.
Pereopod 2 (Fig. 30 B) 100:5:29:66:24:39; basis with long plumose setae; ischium produced as spine; merus with plumose setae; carpus with group of short strong simple setae distally; dactylus setae simple; exopod longer than basis.
Pereopod 3 (Fig. 29 C) 100:20:51:26:17:20; basis, ischium and merus with long plumose setae; carpus with plumose and annulate setae; propodus with annulate seta; dactylus terminal seta long and simple; rudimentary exopod 0.26 times basis length.
Pereopod 4 (Fig. 29 D) 100:13:67:37:20:13; basis, ischium and merus with long plumose setae; carpus with plumose and annulate setae; propodus with annulate seta; dactylus terminal seta long and simple; rudimentary exopod 0.23 times basis length.
Pereopod 5 (Fig. 29 E) 100:16:36:44:16:24; basis, ischium and merus with plumose setae; carpus with plumose and annulate setae; propodus with annulate seta; dactylus with pedunculate seta, terminal seta long and simple.
Telson (Fig. 29 F) 1.9 times as long as pleonite 6, pre-anal part long, post-anal part with 3 setae with setae with single setule laterally, terminal setae short with single setule.
Uropods (Fig. 29 F) peduncles with many setae with single setule medially; endopod triarticulate, with setae with single setule medially and laterally, terminal seta short with single setule; exopod subequal to endopod, with many short setae, terminal seta with wide basis, estimated to be long.
Distribution. Chatham Rise, Challenger Plateau, New Zealand, 346–1239 m.
Remarks. The most similar species in New Zealand waters is Diastylopsis aspratilis, which can be easily differentiated by the carapace and pereopod 1. In D. bicarina the carapace is much less ornamented, the two oblique ridges are entire, the eyelobe has lenses, and pereopod 1 is relatively longer, with the first three articles together distinctly shorter than the last three articles together. In comparison, in D. aspratilis the carapace is much more ornate, with serrate oblique ridges, spines, and rugosities, the eyelobe has no lenses, and pereopod 1 is relatively shorter, with the first three articles together distinctly longer than the last three articles together.
description: Published as part of Gerken, Sarah, 2015, New Zealand Diastylidae and Gynodiastylidae (Crustacea: Cumacea), pp. 1-77 in Zootaxa 4031 (1) on pages 49-50, DOI: 10.11646/zootaxa.4031.1.1, http://zenodo.org/record/289704