Diastylopsis senta, Gerken, 2014

Gerken, Sarah, 2014, Eleven New Species and a New Genus of Diastylidae (Crustacea: Cumacea) from Australia and One New Species from Canada, Records of the Australian Museum 66 (1), pp. 1-62 : 23-26

Diastylopsis senta n. sp.

Figs 14–15

Type material. Holotype ovigerous female, NMV J62368 ; paratype subadult male, dissected, NMV J46865 ; 38°24'30"S 148°42'06"E, 1200 m, R. S. Wilson, 15 Nov. 1981.

Other material examined. 1 manca, NMV J46866 , 38°24'30"S 148°42'06"E, 1200 m, R. S. Wilson, 15 Nov. 1981 .

Diagnosis. Female and subadult male. Carapace with spines anteriorly, increasing in size and density anteriorly, where spines absent carapace is reticulated. Pereonites 3–4 fused dorsally, free ventrally. Pereopods 3–4 without rudimentary exopods in female. Telson with short post-anal portion, without lateral setae. Adult male. Unknown.

Description

Ovigerous female. Holotype ovigerous female, NMV J62368 , 9.1 mm. —Carapace anterior half covered in spines, increasing in length anteriorly, antennal notch oblique; pseudorostral lobes 0.4 × carapace length; eye lobe 0.03 × carapace length; carapace 1.8 × length of pereonites together ( Fig. 14A ).

Subadult male. Paratype subadult male, NMV J46865 , 6.8 mm estimated. —Carapace as in female ( Fig. 14B ). — Antennule peduncle article 1 longest, with 4 simple and 2 pappose setae; article 2 0.9 × article 1 length, with 8 simple and 1 pappose setae; article 3 0.7 × article 2 length, with 8 simple and 3 pedunculate setae; main flagellum of 4 articles, article 2 longest, with 2 aesthetascs and 1 simple and 2 pedunculate setae; accessory flagellum of 3 articles, with 3 simple and 1 pedunculate setae ( Fig. 14C ). —Antenna of 5 articles, peduncle articles 1–4 with pappose and simple setae, article 5 and flagellum without setae, flagellum not divided, subadult male ( Fig. 14D ). —Mandible navicular, with 18 microserrate setae medially ( Fig. 14E ). —Maxillule with 2 endites; outer endite with double row of simple setae; inner endite with 3 simple, 1 microserrate and 1 tricuspid setae; palp with 2 microserrate setae ( Fig. 14F ). —Maxilla with 3 endites; broad endite distal margin with pappose and simple setae, medial margin with row of pedunculate setae and pappose seta; medial narrow endite with 4 microserrate setae terminally; distal narrow endite with 5 microserrate setae terminally; both narrow endites extending past distal margin of broad endite ( Fig. 14G ). —Maxilliped 1 basis produced as lobe with 4 pappose, 2 hook, 1 simple and 1 very stout microserrate setae; ischium absent; merus with plumose seta laterally; carpus 2.4 × merus length, with 6 beak setae and many simple setae medially, plumose seta laterally; propodus 0.8 × carpus length, with 3 plumose and 2 dentate setae; dactylus 0.3 × propodus length, with 2 simple setae ( Fig. 14H ). —Maxilliped 2 basis with 2 simple and 4 plumose setae; ischium 0.02 × basis length, unarmed; merus 10 × ischium length, with plumose seta; carpus 1.6 × merus length, with 3 pappose setae medially, 2 plumose setae laterally; propodus 0.8 × carpus length, with 6 plumose setae medially; dactylus broken off ( Fig. 14I ). —Maxilliped 3 basis 1.8 × length of all other articles together, with 6 pappose setae medially, distal corner produced past distal border of ischium, with 5 plumose setae; ischium 0.06 × basis length, with pappose seta, produced as tooth medially; merus 1.5 × ischium length, medial margin produced as tooth, with pappose seta, with plumose seta laterally; carpus 1.7 × merus length, with 5 plumose setae medially; propodus 1.0 × carpus length, with 4 plumose setae medially; dactylus 0.9 × propodus length, with 4 simple setae terminally; exopod 0.7 × basis length, basal article with unarmed, flagellum with plumo-annulate setae ( Fig. 15A ). —Pereopod 1 basis with pappose setae, produced as strong teeth; exopod 0.7 × basis length, basal article produced as teeth, flagellum with plumo-annulate setae ( Fig. 15B ). —Pereopod 2 basis 0.7 × length of all other articles together, with pappose setae, produced as teeth, with 2 large teeth distally; ischium absent; merus with 2 simple and 1 pappose setae, produced as 2 teeth distally; carpus 1.4 × merus length, with 3 simple setae proximally, distal margin with 5 stout simple setae; propodus 0.2 × carpus length, with 2 simple setae; dactylus 3.2 × propodus length, with 6 simple setae and 5 simple setae terminally; exopod 1.2 × basis length, flagellum with plumo-annulate setae ( Fig. 15C ). —Pereopod 3 basis 0.8 × length of all other articles together, with simple and plumose setae, produced as 3 large teeth proximally; ischium 0.1 × basis length, with 2 plumose setae; merus 7.5 × ischium length, with 5 simple and 2 plumose setae; carpus 0.3 × merus length, with 4 simple and 3 annulate setae; propodus 0.9 × carpus length, with annulate seta; dactylus 0.4 × propodus length, with 2 simple setae and simple seta terminally; exopod 0.6 × basis length, without setae ( Fig. 15D ). —Pereopod 4 basis 0.8 × length of all other articles together, with plumose setae, produced as single large tooth proximally; ischium 0.06 × basis length, unarmed; merus 13 × ischium length, with 6 simple and 3 plumose setae; carpus 0.3 × merus length, with 1 simple and 3 annulate setae; propodus 0.8 × carpus length, with annulate seta; dactylus 0.5 × propodus length, with 2 simple setae and simple seta terminally; exopod 0.7 × basis length, without setae ( Fig. 15E ). —Pereopod 5 basis 0.8 × length of all other articles together, with 2 plumose setae, produced as several teeth; ischium 0.1 × basis length, unarmed; merus 3.3 × ischium length, with 1 simple and 1 plumose setae; carpus 0.8 × merus length, with 1 simple and 2 annulate setae; propodus 0.5 × carpus length, with annulate seta; dactylus 0.5 × propodus length, with simple seta and simple seta terminally ( Fig. 15F ). —Telson 2.3 × length pleonite 6, without lateral setae, with few small simple setae on dorsal surface, 2 simple terminal setae ( Fig. 15G ). —Uropod peduncles 1.9 × pleonite 6 length, 0.8 × telson length, with 8 simple setae with single subterminal setule medially, with 1 or several small simple setae on dorsal surface. Uropod endopod of 3 articles, 0.8 × peduncle length; article 1 1.7 × articles 2 and 3 together, with 10 simple setae with single subterminal setule medially; article 2 0.3 × article 1 length, with 3 simple setae with single subterminal setule medially, 2 pedunculate setae laterally; article 3 1.0 × article 2 length, with 3 simple setae with single subterminal setule medially, with 2 pedunculate setae laterally, terminal seta simple. Uropod exopod of 2 articles, 0.8 × length of endopod; article 1 0.5 × article 2 length, unarmed; article 2 with many simple setae, terminal seta simple ( Fig. 15G ).

Etymology. The species is named senta from the Latin sentus, meaning thorny and rough, in reference to the multitude of spines present on the carapace, producing a rough appearance.

Remarks. Within the Australian Diastylopsis fauna, the carapace architecture is unique, with the spines increasing in size and density anteriorly.

Figures

Figure 14.Diastylopsis senta n. sp. female.Holotype ovigerous female, 9.1 mm, NMV J62368: (A), side view.Paratype subadult male, 6.8 mm estimated, NMV J46865: (B), dorsal view; (C), antennule; (D), antenna; (E), mandible; (F), maxillule; (G), maxilla; (H), maxilliped 1; (I), maxilliped 2. Scale bars A–B = 1.0 mm, C–I = 0.5 mm.

Figure 15. Diastylopsis senta n. sp. female. Paratype subadult male, 6.8 mm estimated, NMV J46865: (A), maxilliped 3; (B), pereopod 1; (C), pereopod 2; (D), pereopod 3, (E), pereopod 4; (F), pereopod 5; (G), pleonite 6, telson and uropods. Scale bar = 1.0 mm.