Diastylis implanus, Gerken, Sarah, 2015

Gerken, Sarah, 2015, New Zealand Diastylidae and Gynodiastylidae (Crustacea: Cumacea), Zootaxa 4031 (1), pp. 1-77 : 33-38

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.6122525
persistent identifier	https://treatment.plazi.org/id/C70EEC59-6E05-FFE7-FF24-1B5FFB0E7DF9
treatment provided by	Plazi
scientific name	Diastylis implanus
status	sp. nov.

Treatment

Diastylis implanus View in CoL n. sp.

( Figs. 18–20 View FIGURE 18 View FIGURE 19 View FIGURE 20 )

Material examined. Holotype: adult male, NIWA 0 93194, TAN0707/139, 39.6373°S, 172.1532°E – 39.6457°S, 172.1522°E, 264–266 m, 7 June 2007. Paratypes: ovigerous female (dissected), NIWA 0 93211, TAN0707/139, 39.6373°S, 172.1532°E – 39.6457°S, 172.1522°E, 264–266 m, 7 June 2007; adult male (dissected), NIWA 0 94978, TAN0707/139, 39.6373°S, 172.1532°E – 39.6457°S, 172.1522°E, 264–266 m, 7 June 2007. Non-type material: 2 adult males, NIWA 0 94978, TAN0707/139, 39.6373°S, 172.1532°E – 39.6457°S, 172.1522°E, 264–266 m, 7 June 2007.

Diagnosis. Female and subadult male. Carapace elongate, with single partial ridge, strongly rugose; ventral margin smooth; antennal notch oblique. Eyelobe without lenses. Pseudorostrum acute, 0.16 times carapace length anterior of eyelobe. Antennule article 2 shorter than article 3. Maxilliped 3 ischium not produced. Pereopod 1 basis ischium merus together shorter than carpus propodus dactylus together, carpus shorter than propodus, propodus shorter than dactylus. Pereopod 2 carpus 2.5 times propodus length. Pereopods 3–4 with rudimentary exopods in female. Telson with 5 lateral setae, more than 0.5 times length of uropod peduncles.

Adult male. Carapace similar to female. Antennule with brush of setae. Telson produced dorsally, with 4–5 lateral setae.

Etymology. From the Latin implanus meaning uneven, in reference to the rugose surface of the carapace.

Description. Adult male holotype 4.4 mm, adult male paratype 4.6 mm. Body ( Figs. 18 View FIGURE 18 A–B). Carapace rugosities short, not connected into longer ridges. Pereonite 5 produced bluntly posteriorly. Pleon unornamented.

Antennule ( Fig. 19 View FIGURE 19 A) article 1 longest, with plumose and simple setae; article 2 with few simple setae; article 3 shortest, unarmed. Main flagellum of 6 articles, article 1 expanded with many simple setae, with 2 aesthetascs terminally; accessory flagellum of 3 articles, extending past distal border of main flagellum article 3, with 2 long simple setae terminally.

Antenna ( Fig. 19 View FIGURE 19 B) peduncle of 5 articles, article 1 and 2 with pappose seta each, article 5 with small ranks of short setae; flagellum extending past posterior border of pleonite 6.

Mandibles–maxilliped 3 not examined.

Pereopod 1 ( Fig. 19 View FIGURE 19 C) missing after basis; basis with many plumose setae; exopod basal article more than 4 times as wide as flagellum.

Pereopod 2 ( Fig. 19 View FIGURE 19 D) 100:6:26:50:18:28; basis produced as strong spine distally, with plumose setae; merus with long plumose setae; dactylus with simple setae; exopod subequal to basis, basal article 4 times as wide as flagellum.

Pereopod 3 ( Fig. 19 View FIGURE 19 E) 100:8:26:16:10:8; basis with plumose, pappose and pedunculate setae; ischium with plumose setae; merus with simple setae; carpus with simple and annulate setae; propodus with annulate seta; dactylus terminal seta long and simple; exopod as long as basis, basal article 3 times as wide as flagellum.

Pereopod 4 ( Fig. 19 View FIGURE 19 F) 100:9:28:19:9:9; basis with plumose and pappose setae; ischium and merus with simple setae; carpus with simple and annulate setae; propodus with annulate seta; dactylus terminal seta long and simple; exopod subequal to basis, basal article 3 times as wide as flagellum.

Pereopod 5 ( Fig. 19 View FIGURE 19 G) 100:21:42:50:17:17; basis with plumose setae; ischium and merus with simple setae; carpus and propodus with simple and annulate setae; dactylus terminal seta long and simple.

Pleopods ( Fig. 19 View FIGURE 19 H) endopod longer than exopod, basal article stout, with moderately long plumose setae.

Telson ( Fig. 19 View FIGURE 19 I) 2.7 times length of pleonite 6; with 4–5 simple setae laterally, terminal setae broken.

Uropods ( Fig. 19 View FIGURE 19 I) peduncles with many short microserrate setae medially; exopod triarticulate, with short microserrate setae medially, article 3 longest, terminal seta short and simple; exopod shorter than endopod, with simple setae, terminal seta long.

Ovigerous female paratype 4.3 mm.

Body ( Figs. 18 View FIGURE 18 C–D). Carapace more rounded than in male; pseudorostrum more acute than in male. Pereonite 5 not produced posteriorly. Pleon unornamented.

Antennule ( Fig. 20 View FIGURE 20 A) article 1 with pappose and simple setae; article 2 with plumose and simple setae; article 3 longest, with simple setae. Main flagellum of 3 articles, with 2 aesthetascs; accessory flagellum of 1 article, more than half length of main flagellum article 1, with short simple setae.

Antenna ( Fig. 20 View FIGURE 20 A) of 2 articles, with pappose seta.

Mandibles ( Fig. 20 View FIGURE 20 B) navicular, lacinia mobilis with 3 cusps, with row of 10–11 microserrate setae medially.

Maxillule ( Fig. 20 View FIGURE 20 C) with 2 endites; palp with 2 short simple setae.

Maxilla ( Fig. 20 View FIGURE 20 D) with 3 endites; broad endite medial row of setae pedunculate; narrow endites long, with simple setae.

Maxilliped 1 ( Fig. 20 View FIGURE 20 E) dactylus slender.

Maxilliped 2 ( Fig. 20 View FIGURE 20 F) ischium visible.

Maxilliped 3 ( Fig. 20 View FIGURE 20 G) 100:5:9:14:18:12; basis expanded distolaterally, with 5 plumose setae, medial marting with plumose setae; ischium and merus broad.

Pereopod 1 ( Fig. 20 View FIGURE 20 H) 100:13:16:63:71:78; very long; basis with many plumose setae; carpus, propodus and dactylus with short simple setae.

Pereopod 2 ( Fig. 20 View FIGURE 20 I) 100:3:23:51:21:33; basis margin with few strong spines, many long plumose setae; ischium unarmed; merus with long plumose setae; carpus and propodus with short simple setae; dactylus with long simple setae; exopod longer than basis.

Pereopod 3–4 not examined, broken.

Pereopod 5 ( Fig. 20 View FIGURE 20 J) 100:18:45:41:23:23; basis to merus with short simple setae; carpus with stout and small simple setae and pedunculate seta; propodus with stout simple seta; dactylus terminal seta long and simple.

Telson ( Fig. 20 View FIGURE 20 K) 2.0 times length of pleonite 6; with 5 setae with single setule laterally, terminal setae with single setule.

Uropods ( Fig. 20 View FIGURE 20 K) peduncles with many short setae with single setule; endopod triarticulate, with setae with single setule medially, terminal seta short with single setule; exopod subequal to endopod, with simple setae, terminal seta long.

Distribution. Challenger Plateau, New Zealand, 264– 266 m.

Remarks. Within the New Zealand fauna, the rugose carapace of D. implanus is unique.