Gynodiastylis chathamensis, Gerken, Sarah, 2015

Gerken, Sarah, 2015, New Zealand Diastylidae and Gynodiastylidae (Crustacea: Cumacea), Zootaxa 4031 (1), pp. 1-77 : 72-75

publication ID	https://doi.org/ 10.11646/zootaxa.4031.1.1
publication LSID	lsid:zoobank.org:pub:19E72EB1-B55C-40C0-AD11-23BA6E97D438
DOI	https://doi.org/10.5281/zenodo.6122608
persistent identifier	https://treatment.plazi.org/id/C70EEC59-6E62-FF88-FF24-1C1FFDBD7E31
treatment provided by	Plazi
scientific name	Gynodiastylis chathamensis
status	sp. nov.

Treatment

Gynodiastylis chathamensis View in CoL n. sp.

( Figs. 39–40 View FIGURE 39 View FIGURE 40 )

Material examined. Holotype: ovigerous female, NIWA 0 93213, TAN0705/285, 43.7967°S, 175.3158°E – 43.8045°S, 175.3148°E, 418–422 m, 27 April 2007. Paratype: ovigerous female (dissected), NIWA 0 93199, TAN0705/83, 43.9790°S, 179.6298°E – 43.9850°S, 179.6218°E, 529–530 m, 9 April 2007.

Diagnosis. Female and subadult male. Carapace without ridges, flared out at the anterior edge; ventral margin below antennal notch serrate; antennal notch deeply excavate. Eyelobe with 3 lenses. Pereopod 2 with some fine hair-like setae on basis and merus. Pereopods 3–5 dactylus and terminal seta simple. Telson shorter than uropod peduncles. Uropod endopod triarticulate.

Adult male. Unknown.

Etymology. The species is named chathamensis for the locality of collection, the Chatham Rise, New Zealand.

Description. Ovigerous female holotype 4.6 mm, preparatory female paratype 3.7 mm. Body ( Figs. 39 View FIGURE 39 A–C). Carapace very smooth, entirely without ridges, flared out at the anterior margin; ventral margin weakly serrate below antennal notch. Eyelobe broad, with 3 distinct lenses. Pleon unornamented. Pleonites 1–3 with stout ventral setae.

Antennule ( Fig. 39 View FIGURE 39 D) article 1 longest, with pappose setae; article 2 shortest, unarmed; article 3 with simple and pedunculate setae. Main flagellum of 4 articles, with 2 aesthetascs and pedunculate seta terminally; accessory flagellum as long as main flagellum, with simple setae.

Antenna ( Fig. 39 View FIGURE 39 E) of 3 articles, with pappose setae.

Mandibles ( Fig. 39 View FIGURE 39 F) navicular, with row of 8 microserrate setae medially.

Maxillule ( Fig. 39 View FIGURE 39 G) of 2 endites; palp with 2 long setae.

Maxilla ( Fig. 39 View FIGURE 39 H) with 3 endites; broad endite medial row of setae pedunculate; narrow endites long, with microserrate setae.

Maxilliped 1 ( Fig. 39 View FIGURE 39 I) basis very short.

Maxilliped 2 ( Fig. 39 View FIGURE 39 J) basis short; ischium visible.

Maxilliped 3 ( Fig. 40 View FIGURE 40 A) 100:12:18:24:33:29; basis weakly produced distolaterally with 3 plumose setae, medial margin with strong spines distally and pappose setae; ischiu, merus and carpus with medial margin produced as spines.

Pereopod 1 ( Fig. 40 View FIGURE 40 B) 100:23:11:93:29:20; basis with pappose and simple setae, medial margin produced as spines increasing in size distally; ischium produced as large spine; propodus brush of setae microserrate; dactylus terminal seta microserrate; exopod slender.

Pereopod 2 ( Fig. 40 View FIGURE 40 C) 100:6:26:22:17:20; basis lateral margin produced as spines, with simple setae and field of fine hair-like setae medially; ischium produced as large spine; merus lateral margin produced as spines, with fine hair-like setae medially; dactylus terminal seta short; exopod shorter than basis.

Pereopod 3 ( Fig. 40 View FIGURE 40 D) 100:10:56:15:10:8; basis with simple and pedunculate setae; merus, carpus with simple setae; propodus with simple seta and pedunculate seta; dactylus terminal seta short and stout.

Pereopod 4 ( Fig. 40 View FIGURE 40 E) 100:14:81:16:14:11; basis to propodus with simple setae; dactylus terminal seta short and stout.

Pereopod 5 ( Fig. 40 View FIGURE 40 F) 100:17:83:29:25:21; basis with simple and pedunculate setae; ischium to propodus with simple setae; dactylus terminal seta short and stout.

Telson ( Fig. 40 View FIGURE 40 G) 3.1 times pleonite 6 length, with pair of very small simple setae terminally.

Uropods ( Fig. 40 View FIGURE 40 G) peduncles with simple seta medially; endopod triarticulate, with few microserrate setae with single setule medially, pedunculate setae laterally, terminal seta long, microserrate, with single setule; exopod slightly shorter than endopod, with fine hair-like setae on lateral margin, with long seta with single setule medially, terminal and lateral subterminal setae long, with long microserrations distally and single long setule.

Distribution. Chatham Rise, New Zealand, 418– 530 m.

Remarks. The most similar species is Axiogynodiastylis fimbriata , with a similar flaring out of the anterior margin of the carapace, also known from Chatham Rise. The new species can be easily differentiated from A. fimbriata by many characters. In the new species, the antennal notch on the carapace is very deep, the eyelobe is broad with distinct lenses, the antennule flagellae are subequal in length, maxilliped 3 and pereopod 1 have distinct spines on the basis and ischium, pereopod 2 has patches of fine hair-like setae on the basis and merus, pereopods 3– 4 have no exopods, the terminal seta on the dactylus of pereopods 3–5 is simple, and the telson is shorter than the uropod peduncles. In contrast, in A. fimbriata the antennal notch is shallow, the eyelobe is narrow and without lenses, the antennule main flagellum is distinctly longer than the accessory flagellum, maxilliped 3 and pereopod 1 have no spines, all articles of pereopod 2 are covered with fine hair-like setae, pereopods 3–4 have rudimentary exopods in female, the terminal seta on the dactylus of pereopods 3–4 is bifurcated at the tip, and the telson is longer than the uropod peduncles.