Diastylis adaioacanthus, Gerken, Sarah, 2015

Gerken, Sarah, 2015, New Zealand Diastylidae and Gynodiastylidae (Crustacea: Cumacea), Zootaxa 4031 (1), pp. 1-77 : 19

Diastylis adaioacanthus n. sp.

( Figs. 8–9 )

Material examined. Holotype: subadult male, NIWA 0 93195, TAN0705/61. Paratype: subadult female (dissected), NIWA 0 93182, TAN0705/61. Non-type material: 1 specimen, NIWA 0 9486, TAN0705/83, 43.9790°S, 179.6298°E – 43.9850°S, 179.6218°E, 529–530 m, 9 April 2007; 1 specimen, NIWA 0 9487, TAN0705/ 41, 43.8363°S, 176.7092°E – 43.8330°S, 176.7127°E, 478–479 m, 5 April 2007; 1 specimen, NIWA 0 9488, TAN0705/41, 43.8363°S, 176.7092°E – 43.8330°S, 176.7127°E, 478–479 m, 5 April 2007; 1 specimen, NIWA 0 9489, TAN0705/178, 43.5212°S, 178.6203°W – 43.5228°S, 178.6315°W, 424–425 m, 18 April 2007; 1 specimen, NIWA 0 9490, TAN0705/99, 44.5607°S, 178.4762°W – 44.5592°S, 178.4830°W, 1076–1103 m, 10 April 2007; 1 specimen, NIWA 0 9491, TAN0705/178, 43.5212°S, 178.6203°W – 43.5228°S, 178.6315°W, 424–425 m, 18 April 2007.

Diagnosis. Female and subadult male. Carapace elongate, carapace and pereon covered in moderate spines, not organized in lines; ventral margin with teeth increasing in size anteriorly; antennal notch absent. Eyelobe without lenses. Pseudorostrum acute, at least 0.25 times carapace length anterior of eyelobe. Antennule article 2 longer than article 3. Maxilliped 3 ischium not produced. Pereopod 1 basis ischium merus together longer than carpus propodus dactylus together, carpus shorter than propodus, propodus and dactylus subequal. Pereopod 2 carpus unknown. Pereopods 3 and 4 without exopods. Telson with 6 lateral setae, more than 0.5 times length of uropod peduncles.

Adult male. Unknown.

Etymology. The species name is a combination of the Greek adai meaning abundant, and acanthus meaning spines, in reference to the abundance of spines on the carapace and pereon.

Description. Subadult male holotype 10.0 mm, subadult female paratype 9.7 mm. Body ( Figs. 8 A–B). Carapace expanded dorsolaterally, with posterior depression, posterior margin serrate; pair of larger spines on tips of pseudorostrum. Pleon with spines dorsally; pleonite 1 with spines ventrally.

Subadult female paratype. Antennule ( Fig. 8 C) article 1 longer than articles 2–3 together, with plumose and simple setae; article 2 with simple setae; article 3 shortest, unarmed. Flagellae broken off.

Antenna not examined.

Mandibles ( Fig. 8 D) navicular, with row of 12 microserrate setae medially.

Maxillule not examined.

Maxilla ( Fig. 8 E) with 3 endites; broad endite medial row of setae pedunculate; narrow endites with microserrate setae.

Maxilliped 1 ( Fig. 8 F) with long plumose setae on carpus and propodus.

Maxilliped 2 ( Fig. 8 G) ischium visible.

Maxilliped 3 ( Fig. 9 A) 100:6:10:16:19:11; basis distal corner weakly produced, with 3 plumose setae.

Pereopod 1 ( Fig. 9 B)100:11:14:34:41:38; basis with many strong spines, largest at distal corner, with plumose setae.

Pereopod 2 ( Fig. 9 C)100:7:21:40:?(broken off); basis with strong spines and many plumose setae; exopod longer than basis.

Pereopod 3 ( Fig. 9 D)100:8:30:24:6:6; with many plumose and simple setae; carpus and propodus with annulate setae; dactylus terminal seta long and simple; exopod absent.

Pereopod 4 ( Fig. 9 E)100:10:33:41:8:10; with few plumose and simple setae; merus, carpus and propodus with annulate setae; dactylus terminal seta long and simple; exopod absent.

Pereopod 5 ( Fig. 9 F) 100:11:41:52:11:11; basis short, with spines and few simple setae; carpus and propodus with annulate setae; dactylus terminal seta long and simple.

Telson ( Fig. 9 G) longer than pleonite 6, with 6 simple setae laterally, terminal setae simple and short.

Uropods ( Fig. 9 G) peduncles longer than telson , with simple setae medially; endopod triarticulate, with simple setae medially, terminal seta missing; exopod broken, with simple setae.

Distribution. Chatham Rise, New Zealand, 424–1103 m.

Remarks. Among the three similar species, D. adaioacanthus n. sp., D. acanthoelachys n. sp. and D. acuminata , D. adaioacanthus stands out because the carapace is more elongate, the spines are larger, and the pseudorostrum extends twice as far in front of the eyelobe as in the other two species.

Figures

FIGURE 8. Diastylis adaioacanthus n. sp. holotype subadult female (NIWA 093195). A, side view. Paratype subadult female (NIWA 093182). B, dorsal view; C, antennule; D, mandible; E, maxilla; F, maxilliped 1; G, maxilliped 2.

FIGURE 9. Diastylis adaioacanthus n. sp. paratype subadult female (NIWA 093182). A, maxilliped 3; B, pereopod 1; C, pereopod 2; D, pereopod 3; E, pereopod 4; F, pereopod 5; G, pleonite 6, telson and uropods.