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

description: Diastylopsis aspratilis n. sp.
(Figs. 23–27)
Material examined. Holotype: preparatory female, NIWA 0 93205, TAN0705/255, 43.5300°S, 178.5048°E – 43.5363°S, 178.5118°E, 346 m, 24 April 2007. Paratypes: preparatory female (dissected), NIWA 0 93188, TAN0705/255, 43.5300°S, 178.5048°E – 43.5363°S, 178.5118°E, 346 m, 24 April 2007; adult male (dissected), NIWA 0 93189, TAN0705/255, 43.5300°S, 178.5048°E – 43.5363°S, 178.5118°E, 346 m, 24 April 2007. Non-type material: 5 specimens, NIWA 13068, E417, 45.2000°S, 171.8167°E, 860 m, 13 October 1965; 16 specimens, NIWA 46218, TAN0705/251, 42.9958°S, 178.9957°E – 42.9910°S, 179.0052°E, 520–530 m, 24 April 2007; 4 specimens, NIWA 0 9461, TAN0705/178, 43.5212°S, 178.6203°W – 43.5228°S, 178.6315°W, 424–425 m, 18 April 2007; 1 specimen, NIWA 0 94962, TAN0705/83, 43.9790°S, 179.6298°E – 43.9850°S, 179.6218°E, 529–530 m, 9 April 2007; 1 specimen, NIWA 0 94963, TAN0705/141; 1 specimen, NIWA 0 94964, TAN0705/251, 42.9958°S, 178.9957°E – 42.9910°S, 179.0052°E, 520–530 m, 24 April 2007; 2 specimens, NIWA 0 94965, TAN0705/49, 44.4862°S, 177.1413°E – 44.4841°S, 177.1416°E, 1235–1239 m, 6 April 2007; 12 specimens, NIWA 0 94966, TAN0705/83, 43.9790°S, 179.6298°E – 43.9850°S, 179.6218°E, 529–530 m, 9 April 2007; 3 specimens, NIWA 0 94967, TAN0705/285, 43.7967°S, 175.3158°E – 43.8045°S, 175.3148°E, 418–422 m, 27 April 2007; 1 specimen, NIWA 0 94968, 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 weakly serrate parallel ridges, short ridges and spines arranged in lines and pairs anterior of the oblique ridges, carapace rugose posterior of oblique ridges. Eyelobe without lenses. Pereonites 3–4 not fused, pereonite 4 narrow dorsally. Pereopods 3–4 with rudimentary exopods in female. Telson extending to end of uropod endopod, with 3 pairs lateral setae, 2 terminal setae.
Adult male. Carapace less rugose than in female, spines anterior of oblique ridges smaller than in female. Pereonite 5 produced moderately posteriorly. Pleonite 1 without ventral spines. Pereopod 4 ischium not produced. Telson extending to midpoint of uropod endopod article 1, with 4–5 pairs lateral setae.
Etymology. From the Latin aspratilis meaning rough or scaly, in reference to the serrate ridges, spines, and rugosities on the carapace.
Description. Preparatory female holotype 6.1 mm, preparatory female paratype 5.8 mm. Body (Figs. 23 A–C). Carapace eyelobe with pair of spines. Pleon unornamented.
Antennule (Fig. 24 A) short and stout; article 1 longest, with plumose seta; articles 2 and 3 with few small simple setae. Main flagellum short, of 3 articles, with 2 aesthetascs; accessory flagellum small, of 2 articles, with few small setae.
Antenna (Fig. 24 A) of 3 articles, terminal article margin irregular, with pappose and plumose setae.
Mandibles (Fig. 24 B) navicular, lacinia mobilis with 3 cusps, with row of 12 microserrate medially.
Maxillule (Fig. 24 C) with 2 endites; palp with 2 microserrate setae.
Maxilla (Fig. 24 D) with 3 endites; broad endite medial row of pedunculate setae, distal margin with pappose setae; narrow endites long, with microserrate setae.
Maxilliped 1 (Fig. 24 E) medial lobe with few setae.
Maxilliped 2 (Fig. 24 F) ischium not visible.
Maxilliped 3 (Fig. 24 G) 100:4:5:11:10:10; basis long and slender, margin serrate, with spine at mediolateral corner, distolateral corner weakly produced, with 3 short setae.
Pereopod 1 (Fig. 24 H) 100:11:18:31:39:38; long; basis with many plumose setae; carpus, propodus with short setae; dactylus with short setae, long simple setae distally.
Pereopod 2 (Fig. 24 I) 100:5:32:37:18:26; basis margin serrate, with many plumose setae; merus margin serrate; dactylus terminal setae long and simple; exopod longer than basis; preparatory broodplate margin with spines.
Pereopod 3 (Fig. 26 A) 100:10:75:30:23:15; with many long plumose setae; merus, carpus and propodus with annulate setae; dactylus terminal seta long and simple; rudimentary exopod 0.35 times basis length, with plumose setae.
Pereopod 4 (Fig. 26 B) 100:13:94:38:25:25; basis with long plumose setae; ischium with simple seta; merus with simple, plumose and plumo–annulate setae; carpus and propodus with annulate setae; dactylus terminal seta short and simple; rudimentary exopod 0.41 times basis length.
Pereopod 5 (Fig. 25 C) 100:16:100:63:37:32; basis with long plumose setae; ischium with simple seta; merus with simple and plumose setae; carpus and propodus with annulate setae; dactylus terminal seta short.
Telson (Fig. 25 D) 1.8 times length of pleonite 6, with short post-anal part, with 3 lateral simple setae, terminal setae short and simple.
Uropods (Fig. 25 D) peduncles with few simple setae medially; endopod triarticulate, with many simple setae medially, terminal seta long and simple; exopod shorter than endopod, with many simple setae, terminal seta long.
Adult male paratype.
Body (Figs. 23 D–E). Carapace more elongate, fewer rugosities and smaller spines, dorsal outline much less rough than in female. Pereonite 5 slightly produced posteriorly. Pleon unornamented.
Antennule (Fig. 26 A) short and stout, article 3 longest, with plumose seta; article 2 with few short simple setae; article 3 shortest, with few small simple setae. Main flagellum of 5 articles, article modestly expanded with simple that are shorter than aesthetascs; accessory flagellum of 4 articles, nearly as long as main flagellum, with 1 long simple seta terminally.
Antenna (Fig. 26 B) peduncle article 4 with few short setae, article 5 with ranks of short setae; flagellum extending past telson.
Mandibles – maxilliped 1 not examined.
Maxilliped 2 (Fig. 26 C) basis broad.
Maxilliped 3 (Fig. 26 D) 100:5:7:6:6:5; basis long and slender, with short plumose setae, expanded distolaterally with 3 short plumose setae, mediolateral corner produced as spine; exopod basal article more than twice as wide as flagellum.
Pereopod 1 (Fig. 26 E) 100:5:8:20:18:15; basis with many plumose setae, mediolateral corner produced as spine; ischium, merus, carpus unarmed; propodus with small simple seta; dactylus with simple setae; exopod basal article 7 times as wide as flagellum.
Pereopod 2 (Fig. 26 F) 100:7:25:45: broken; basis broad, with may plumose setae; merus with plumose seta; carpus with cluster of simple setae on distal margin; exopod longer than basis, basal article more than 6 times as wide as flagellum.
Pereopod 3 (Fig. 27 A) 100:4:45:15:11:9; basis broad, with plumose and pedunculate setae; merus with plumose setae; carpus and propodus with annulate setae; dactylus terminal seta long; exopod basal article more than 6 times as wide as flagellum.
Pereopod 4 (Fig. 27 B) 100:11:61:21:16:16; basis broad, with plumose, simple and pedunculate setae; ischium and merus with plumose setae; carpus and propodus with simple and annulate setae; dactylus terminal seta long; exopod basal article more than 6 times as wide as flagellum.
Pereopod 5 (Fig. 27 C) 100:9:64:45:26:18; basis slender, with plumose setae; ischium with simple setae; merus with plumose and simple setae; carpus and propodus with simple and annulate setae; dactylus terminal seta long.
Pleopod 1 (Fig. 27 D) rami equal in length, with plumoannulate setae.
Pleopod 2 (Fig. 27 E) rami equal in length, with plumoannulate setae.
Telson (Fig. 27 F) 2.5 times length of pleonite 6, with dorsal elevation, with 4–5 short simple setae laterally, terminal setae long and simple.
Uropods (Fig. 27 F) peduncles with many setae with single setule medially; endopod triarticulate, with many setae with single setule medially, pedunculate and simple setae laterally, terminal seta long and simple; exopod subequal to endopod, with few short simple setae and 2 long simple setae terminally.
Distribution. Chatham Rise, New Zealand, 196–1239 m.
Remarks. Diastylopsis aspratilis is most similar in carapace morphology to D. trisetosa from Australia. Females of the two species can be differentiated by the telson, extending to the end of the uropod endopod and with 2 terminal setae in the new species, and only extending to the posterior border of uropod endopod article 1 and with 3 terminal setae in D. trisetosa. The adult male of D. trisetosa is unknown. Within New Zealand waters, the most similar species is D. bicarina, which can easily be differentiated by the carapace, maxilliped 3, pereopod 1 and telson. In D. bicarina the carapace has two entire oblique parallel ridges, no spines anterior of the ridges, and no rugosities on the carapace posterior of the oblique ridges; the eyelobe has lenses; maxilliped 3 basis is less than twice the length of the other articles together; pereopod 1 has the basis ischium merus together shorter than the carpus propodus dactylus together; the telson extends to the posterior border of the uropod peduncles. In comparison, D. aspratilis has serrate ridges, spines anterior of the ridges, and rugosities posterior of the serrate ridges; the eyelobe has no lenses; maxilliped 3 basis is more than twice the length of the other articles together; pereopod 1 has the basis ischium merus together longer than the carpus propodus dactylus together; the telson extends past the posterior border of the uropod peduncles.
description: Published as part of Gerken, Sarah, 2015, New Zealand Diastylidae and Gynodiastylidae (Crustacea: Cumacea), pp. 1-77 in Zootaxa 4031 (1) on pages 43-49, DOI: 10.11646/zootaxa.4031.1.1, http://zenodo.org/record/289704