Diastylis spinacellulosus, Gerken, Sarah, 2015

Gerken, Sarah, 2015, New Zealand Diastylidae and Gynodiastylidae (Crustacea: Cumacea), Zootaxa 4031 (1), pp. 1-77 : 39-42

Diastylis spinacellulosus n. sp.

( Figs. 21–22 )

Material examined. Holotype: subadult male, NIWA 0 93193, TAN0705/24, 44.1208°S, 174.8432°E – 44.1242°S, 174.8448°E, 512–513 m, 4 April 2007. Paratype: subadult female (dissected), NIWA 0 93191, TAN0705/83, 43.9790°S, 179.6298°E – 43.9850°S, 179.6218°E, 529–530 m, 9 April 2007. Non-type material: 2 specimens, NIWA 0 94976, 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 elongate, covered in small pits, with spines organized in lines, increasing in size anteriorly to 4 very large spines; ventral margin serrate; antennal notch present. Pereonites and pleonites 1–2 or 1–3 with large paired spines dorsally, pleonite 1 with pair of spines ventrally, pleonites 3–6 or 4–6 with small spines. 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 shorter than propodus, propodus longer than dactylus. Pereopod 2 carpus 4 times propodus length. Pereopods 3–4 without exopods. Telson with 2 lateral setae, longer than uropod peduncles.

Adult male. Unknown.

Etymology. Combination of the Latin spina for spines, and cellulosus meaning little holes, to describe the carapace with a pattern of spines that is also covered with small pits.

Description. Subadult male holotype 5.6 mm, subadult female paratype 7.8 mm. Body ( Figs. 21 A–C). Carapace with a dorsal depression, entire ventral margin serrate; longest row of spines parallel to margin of carapace, from middorsal moving posteriorly, then ventrally and forward anterolaterally, increasing in size and ending in a very large spine near anterior margin. Another row of spines moving sinuously from near the posterior border anteriorly, ending in very large spine parallel to eyelobe. Pseudorostrum with a row of small spines dorsally. Pereonites with very paired dorsal spines, with smaller spines on the lateral surface near the ventral margin. Pleon with large paired spines on pleonites 1–2 or 1–3, with smaller scattered spines on remaining pleonites, with pair of spines ventrally on pleonite 1, small in female and large in male.

Subadult female paratype.

Antennule ( Fig. 21 D) article 1 longest, with plumose, short and long simple setae; article 2 with plumose and short simple setae; article 3 broken, with short simple setae.

Antenna not examined.

Mandibles ( Fig. 21 E) navicular, with row of 12 long microserrate setae medially.

Maxillule ( Fig. 21 F) with 2 endites; palp with 2 microserrate setae.

Maxilla ( Fig. 21 G) with 3 endites; broad endite medial row of setae pedunculate; narrow endites short, with simple setae.

Maxilliped 1 ( Fig. 21 H) stout; basis with only pappose setae; carpus without beak setae, with few short simple setae.

Maxilliped 2 ( Fig. 21 I) ischium visible.

Maxilliped 3 ( Fig. 22 A) 100:11:8:11:17:13; basis produced distolaterally with 4 plumose setae, medial margin with single spine not at corner, with few plumose setae.

Pereopod 1 ( Fig. 22 B) 100:4:12:37:29:broken; basis margins produced as spines, with many plumose setae; carpus long, with many short simple setae; exopod basal article with spines.

Pereopod 2 ( Fig. 22 C) 100:4:24:58:13:27; basis margins produced as spines, with 2 large spines distally, with many plumose and small simple setae; ischium produced as strong spine; merus produced as teeth; carpus long; dactylus with long simple setae; exopod longer than basis, basal article with 1 spine.

Pereopod 3 ( Fig. 22 D) 100:8:27:24:8:8; basis with plumose and small simple setae; ischium and merus with simple setae; carpus and propodus with simple and annulate setae; dactylus terminal seta long and simple; exopod absent.

Pereopod 4 ( Fig. 22 E) 100:12:32:32:10:15; basis with spines, small simple setae; merus with simple setae; carpus and propodus with simple and annulate setae; dactylus terminal seta long and simple; exopod absent.

Pereopod 5 ( Fig. 22 F) 100:17:48:52:10:14; basis with spine and plumose seta; merus with few small setae; carpus and propodus with annulate setae; dactylus terminal seta long and simple.

Telson ( Fig. 22 G) 3.0 times length of pleonite 6; with several short simple setae on pre-anal part, with few small simple setae and 2 setae with single setule laterally, terminal setal bases small, expected to be short.

Uropods ( Fig. 22 G) peduncles with few setae with single setule and small simple setae; endopod biarticulate, with pedunculate setae laterally and short setae with single setule medially, terminal seta short with single setule; exopod slightly longer than endopod, with many moderate simple setae, terminal seta unknown.

Distribution. Chatham Rise, Challenger Plateau, New Zealand, 512– 805 m.

Remarks. The carapace morphology is unique within the New Zealand and Australian fauna, with many spines arranged in lines and the carapace covered in small pits.

Figures

FIGURE 21. Diastylis spinacellulosus n. sp. holotype subadult male (NIWA 093193). A, side view. Paratype subadult female (NIWA 093191). B, dorsal view; C, side view; D, antennule; E, mandible; F, maxillule; G, maxilla; H, maxilliped 1; I, maxillipeds 2.

FIGURE 22. Diastylis spinacellulosus n. sp. paratype subadult female (NIWA 093191). A, maxilliped 3; B, pereopod 1; C, pereopod 2; D, pereopod 3; E, pereopod 4; F, pereopod 5; G, pleonite 6, telson and uropods.