Makrokylindrus eirmoacanthus, 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 : 46-49

Makrokylindrus eirmoacanthus n. sp.

Figs 30–31

Type material. Holotype subadult female, AM P85802; paratype subadult female, dissected, AM P85803; paratypes, 1 ovigerous female, 5 subadult females, AM P85804; 33°40'– 33°43'S 152°04'– 152°06'E, 1108–1115 m, FRV “Kapala”, 19 Dec. 1985 . Paratype subadult female, dissected, AM P85806, 33 °35'– 33°37'S 152°05'E, 1144 m, FRV “Kapala”, 10 Dec. 1980 .

Other material examined. 2 individuals, AM P85805, 33°29'S 152°06'E, 523 m, FRV “Kapala”, 11 Feb. 1986 . 1 female, AM P85807, 33°26'S 152°11'E, 869 m, FRV “Kapala”, 6 Dec. 1979 . 1 ovigerous female, 3 subadult females, AM P85808, 33 °31'– 33°33'S 152°07'– 152°08'E, 914 m, R. Springthorpe, 10 Dec. 1980 .

Diagnosis. Female and subadult male. Carapace produced as 2 pairs of large horns, one pair on the pseudorostral lobes, one pair ventrolaterally, with many short serrate ridges, ventral margin strongly serrate, with serrate ridges on pseudorostrum, pseudorostrum ending in pair of large teeth. Pereonites 3–5 and pleonites 1–3 with pair of large dorsal spines. Uropod endopod of 2 articles. Adult male. Unknown.

Description

Subadult female. Holotype subadult female, AM P85802, 7.5 mm; paratype subadult female, AM P85803, 7.1 mm; paratype subadult female, AM P85806, 7.3 mm. —Carapace bulbous, branchial regions expanded, with many lines of small spines, with 2 pairs of large spines, one on pseudorostral lobes, one at ventrolateral corner; pseudorostral lobes 0.4 × carapace length, with row of small spines terminating in long spine, with pair of medium spines terminally; eye lobe 0.04 × carapace length, without lenses; carapace 2.0–2.4 × length of pereonites together. Pereonites 1–2 with 1–2 rows of small spines; pereonites 3–5 with pair of large spines dorsally. Pleonites 1–3 with pair of large spines dorsally; pleonites 4–6 with scattered small spines, pleonite 5 longest ( Figs 30A–C ). — Paratype subadult female, AM P85803, 7.1 mm. —Antennule peduncle article 1 0.9 × length of articles 2 and 3 together, with 2 plumose setae; article 2 0.6 × article 1 length, with simple seta; article 3 0.8 × article 2 length, with 3 simple setae; main flagellum of 4 articles, with 1 aesthetasc and 2 simple setae; accessory flagellum of 2 articles, 0.2 × main flagellum length, shorter than main flagellum article 1, with 3 simple setae ( Fig. 30D ). —Antenna of 2 articles; article 1 long, with pappose seta; article 2 with 3 plumose setae ( Fig. 30E ). —Mandible with 11 microserrate setae medially, lacinia mobilis with 3 cusps ( Fig. 30F ). —Maxillule with 2 endites; outer endite with double row of setae bulbous terminally; inner endite with 1 simple, 2 microserrate and 2 tricuspid setae; palp with single seta ( Fig. 30G ). —Maxilla with 3 endites; broad endite distal margin with row of simple setae and pappose setae, medial margin with row of pedunculate setae and pappose seta; medial narrow endite with 3 setae with long setules proximally, short setules distally, bulbous terminally; distal narrow endite with 3 setae with long setules proximally, short setules distally, bulbous terminally; both narrow endites extending past distal margin of broad endite ( Fig. 30H ). —Maxilliped 1 basis produced as lobe, with 5 pappose, 2 hook and 1 very stout simple setae; ischium absent; merus lateral margin lined with fine hair-like setae; carpus 1.8 × merus length, with 4 beak and 7 pappose setae medially, lateral margin lined with fine hair-like setae, with plumose seta; propodus 0.5 × carpus length, with 2 simple, 2 dentate and 2 plumose setae; dactylus 0.6 × propodus length, with 2 simple setae ( Fig. 30I ). —Maxilliped 2 basis 1.2 × length of all other articles together, with 2 simple and 1 plumose setae distally; ischium 0.04 × basis length, with pappose seta; merus 5.0 × ischium length, with 2 pappose setae medially, 2 plumose setae laterally; carpus 1.6 × merus length, with 4 pappose setae medially, plumose seta laterally; propodus 0.6 × carpus length, with 3 simple and 3 pappose setae medially, 2 plumose setae laterally; dactylus 0.6 × propodus length, with 3 simple setae terminally ( Fig. 30J ). —Maxilliped 3 slender, basis 1.8 × length of all other articles together, with 7 plumose setae medially, distal corner with 2 simple and 4 plumose setae; ischium 0.09 × basis length, unarmed; merus 0.8 × ischium length, with plumose seta laterally; carpus 1.8 × merus length, with plumose seta medially, plumose seta laterally; propodus 1.0 × carpus length, with 2 plumose setae medially, simple seta laterally; dactylus 0.9 × propodus length, with 5 simple setae terminally; exopod 0.6 × basis length, basal article unarmed, flagellum with plumo-annulate setae ( Fig. 31A ). —Pereopod 1 basis 0.9 × length of all other articles together, with many plumose setae, lateral margins produced as strong teeth; ischium 0.08 × basis length, with plumose seta; merus 0.8 × ischium length, with 2 plumose setae; carpus 5.8 × merus length, with simple seta; propodus 0.8 × carpus length, with 2 simple setae; dactylus 0.8 × propodus length, with 5 simple setae and 3 simple setae terminally; exopod 0.6 × basis length, basal article with plumose seta, margin produced as many strong teeth, flagellum with plumo-annulate setae ( Fig. 31B ). —Pereopod 2 basis 0.7 × length of all other articles together, with 6 plumose setae, lateral margins produced as teeth, increasing in size distally; ischium 0.07 × basis length, produced as single large tooth; merus 3.3 × ischium length, with 2 plumose setae, margins produced as teeth, increasing in size distally; carpus 3.0 × merus length, with simple seta; propodus 0.2 × carpus length, with 2 simple setae; dactylus 2.5 × propodus length, with 4 simple setae and 2 simple setae terminally; exopod 1.1 × basis length, basal article produced as many teeth, decreasing in size distally, flagellum with plumo-annulate setae ( Fig. 31C ). —Pereopod 3 basis 1.5 × length of all other articles together, with 1 plumose and 1 pappose setae, lateral margins produced as teeth, decreasing in size distally; ischium 0.1 × basis length, with plumose seta; merus 2.4 × ischium length, with simple seta; carpus 0.8 × merus length, with 1 simple and 4 annulate setae; propodus 0.3 × carpus length, with annulate seta; dactylus 1.3 × propodus length, with simple seta and simple seta terminally ( Fig. 31D ). —Pereopod 4 basis 1.0 × length of all other articles together, with 2 plumose setae, lateral margins produced as scattered teeth, decreasing in size distally; ischium 0.1 × basis length, unarmed; merus 3.8 × ischium length, unarmed; carpus 0.8 × merus length, with 5 annulate setae; propodus 0.3 × carpus length, with 1 simple and 1 annulate setae; dactylus 1.3 × propodus length, with simple seta and simple seta terminally ( Fig. 31E ). —Pereopod 5 basis 0.7 × length of all other articles together, with 2 simple setae, margin produced as tooth; ischium 0.1 × basis length, unarmed; merus 2.8 × ischium length, with simple seta; carpus 1.5 × merus length, with 4 annulate setae; propodus 0.3 × carpus length, with 1 simple and 1 annulate setae; dactylus 1.0 × propodus length, with simple seta and simple seta terminally ( Fig. 31F ). — Paratype subadult female, AM P85806, 7.3 mm. —Telson 3.0 × length of pleonite 6, without lateral setae, 2 simple terminal setae ( Fig. 31G ). —Uropod peduncles 2.7 × pleonite 6 length, 0.9 × telson length, with 5 small simple setae proximally. Uropod endopod of 2 articles, 0.4 × peduncle length; article 1 with simple seta with single subterminal setule medially; article 2 0.9 × article 1 length, with 2 simple setae with single subterminal setule medially, with simple seta laterally, terminal seta simple. Uropod exopod of 2 articles, 1.3 × length of endopod; article 1 0.3 × article 2 length; article 2 with 9 simple setae laterally, terminal seta simple ( Fig. 31G ).

Etymology. The species is named eirmoacanthus from the Greek eirmos meaning in a line in combination with acanthus meaning spines. The name refers to the multiple lines of spines present on the carapace.

Remarks. This is the only species in the genus currently known from Australian waters. The carapace ornamentation is unique within the Australian diastylid fauna.

Figures

Figure 30. Makrokylindrus eirmoacanthus n. sp.female.Holotype subadult female, 7.5 mm,AM P85802:(A), dorsal view.Paratype subadult female, 7.1 mm, AM P85803: (B), dorsal view; (D), antennule; (E), antenna; (F), mandible; (G), maxillule; (H), maxilla; (I), maxilliped 1; (J), maxilliped 2. Paratype subadult female, 7.3 mm, AM P85806: (C), dorsal/side view. Scale bars A–C = 5.0 mm, D–J = 0.5 mm.

Figure 31. Makrokylindrus eirmoacanthus n. sp. female.Paratype subadult female, 7.1 mm,AM P85803:(A), maxilliped 3; (B), pereopod 1; (C), pereopod 2; (D), pereopod 3; (E), pereopod 4; (F), pereopod 5. Paratype subadult female, 7.3 mm, AM P85806: (G), pleonite 6, telson and uropod. Scale bar = 1.0 mm.