Diastylis curtain, Gerken, Sarah, 2015

Gerken, Sarah, 2015, New Zealand Diastylidae and Gynodiastylidae (Crustacea: Cumacea), Zootaxa 4031 (1), pp. 1-77 : 22

Diastylis curtain n. sp.

(Figs. 10–11)

Material examined. Holotype: subadult female, NIWA 0 93179, TAN0707/105, 40.1277°S, 170.2140°E – 40.1352°S, 170.2090°E, 803–805 m, 5 June 2007. Paratype: subadult female (dissected), NIWA 0 93192, TAN0707/105, 40.1277°S, 170.2140°E – 40.1352°S, 170.2090°E, 803–805 m, 5 June 2007.

Diagnosis. Female and subadult male. Carapace globular, smooth, with pair of large spines with shorter spines between anteriorly, with few short spines dorsal of row, pair of spines at tips of pseudorostrum; ventral margin smooth; antennal notch oblique. Eyelobe without lenses. Pseudorostrum acute, 0.2 times carapace length anterior of eyelobe. Antennule article 2 shorter than article 3. Maxilliped 3 ischium not produced. Pereopod 1 basis ischium merus together longer than carpus propodus dactylus together, carpus longer than propodus, propodus and carpus subequal. Pereopod 2 carpus 4 times propodus length. Pereopods 3–4 without exopods. Telson with 3 lateral setae, more than 0.5 times length of uropod peduncles.

Adult male. Unknown.

Etymology. The arrangement of two large spines with a row of smaller spines between resembles a curtain wall, a type of castle wall with tall towers at either end with a shorter wall between, thus the species is named curtain ; used as a noun in apposition.

Description. Subadult female holotype 5.5 mm, subadult female paratype 5.1 mm. Body (Figs. 10A–B). Carapace more than twice as long as pereon; pereonites with large dorsal spines, pereonite 5 with ventral spine. Pleon with pair of large spines dorsally on pleonites 1–2, and with large ventral spines on pleonite 1.

Antennule (Fig. 10C) peduncle article 1 longest, with plumose and many simple setae; article 2 and 3 narrower than article 1, with few setae. Main flagellum of 3 articles, longer than peduncle article 3, with 2 aesthetascs and few simple setae; accessory flagellum half as long as main flagellum article 1, with few simple setae.

Antenna (Fig. 10D) of 3 articles, with pappose and plumose setae.

Mandibles not examined.

Maxillule (Fig. 10E) with 2 endites, palp with 2 microserrate setae.

Maxilla (Fig. 10F) with 3 endites; broad endite medial row of setae pedunculate; narrow endites long, with simple setae.

Maxilliped 1 (Fig. 10G) stout, with long plumose setae on carpus and propodus; carpus without beak setae, with several pappose setae.

Maxilliped 2 (Fig. 10H) basis with few setae, ischium visible.

Maxilliped 3 (Fig. 10I) 100:10:7:16:15:13; basis with few large spines on medial margin, no setae on distolateral corner.

Pereopod 1 ( Fig. 11 A) 100:8:11:35:30:28; basis with spines on lateral margin, with simple, pappose and plumose setae.

Pereopod 2 ( Fig. 11 B) 100:5:25:60:16:32; basis with spines on medial and lateral margins increasing in length distally; ischium produced as large spine; merus with large spines; carpus and propodus with simple setae; dactylus with simple setae, terminal seta plumose; exopod basal article with spines on lateral margin, longer than basis.

Pereopod 3 ( Fig. 11 C) 100:7:27:24:7:11; basis with spine and simple setae proximally; ischium with plumose seta; carpus and propodus with annulate setae; dactylus terminal seta long and simple; exopod absent.

Pereopod 4 ( Fig. 11 D) 100:13:43:45:13:15; basis with simple setae; merus with simple setae; carpus and propodus with annulate setae; dactylus terminal seta long and simple; exopod absent.

Pereopod 5 ( Fig. 11 E) 100:20:48:72:24:16; basis with simple seta; carpus and propodus with annulate setae; dactylus terminal seta long and simple. Telson ( Fig. 11 F) 1.7 times length of pleonite 6, with 3 lateral seta with single setule, terminal setae long and microserrate.

Uropods ( Fig. 11 F) peduncle with 3 setae with single setule medially; endopod biarticulate, with few setae with single setule medially, terminal seta moderate, with single setule; exopod longer than endopod, with simple setae, terminal seta stout and long.

Distribution. Challenger Plateau, New Zealand, 803– 805 m.

Remarks. The most similar species is D. homoacanthus n. sp. which also has a smooth globular carapace with few larger anterior spines. However, the pattern of spines is quite different, with 2 large spines with shorter spines between them in D. curtain , while in D. homoacanthus the spines are homogenous in size.

Figures

FIGURE 11. Diastylis curtain n. sp. paratype subadult female (NIWA 093192). A, pereopod 1; B, pereopod 2; C, pereopod 3; D, pereopod 4; E, pereopod 5; F, pleonite 6, telson and uropods.