Chalarostylis bruunae, Gerken, 2018

Gerken, Sarah, 2018, The Lampropidae (Crustacea: Cumacea) of the World, Zootaxa 4428 (1), pp. 1-192 : 44-47

Chalarostylis bruunae n. sp.

( Figs 12–13 )

Type material. Holotype subadult female, USNM 389843 , 29°20’S, 36°26’E, 5000 m, collected by R / V Anton Bruun.

Diagnosis. Carapace with setae, pereon and pleon without setae. Carapace dorsal crest without teeth or serrations, setae on frontal lobe and pseudorostral lobes. Pereopod 1 without serrate carinae on carpus and propodus. Telson 2.0 length of pleonite 6, telson with 8–9 lateral setae and 3 terminal setae, lateral and terminal setae subequal. Adult male unknown.

Description. Holotype subadult female, USNM 389843. Subadult female, 6.3 mm. Carapace smooth, with setae on frontal lobe and pseudorostral lobes, elevated dorsally posteriorly, antennal notch absent; pseudorostral lobes 0.4 carapace total length, serrated anteriorly; eyelobe 0.03 carapace length, no lenses; carapace longer than pereonites together; pereonite 1 exposed dorsally, not visible laterally ( Fig. 12A, B ).

Antennule peduncle article 1 longest, margin with teeth, produced as lobe distally, lobe with 2 pedunculate setae, with 14 simple setae; article 2 with 3 pedunculate and 12 simple setae; article 3 shortest, with 1 simple seta; main flagellum of 4 articles, with 2 simple and 2 aesthetasc setae terminally; accessory flagellum small, barely longer than first article of main flagellum, of 2 articles, with simple setae terminally ( Fig. 12C ).

Antenna rudimentary.

Mandible, maxillule, maxilla, maxilliped 1 not examined.

Maxilliped 2 basis shorter than other articles together, with 1 plumose and 2 pappose setae; ischium unarmed; merus with 1 plumose and 1 pappose setae; carpus with 1 pappose seta distally and 5 pappose setae medially; propodus with 6 pappose setae medially and 1 pappose seta distally; dactylus with 4 simple setae terminally ( Fig. 12D ).

Maxilliped 3 basis subequal to all other articles together, expanded distally, distal corner with 4 plumose setae, medial margin with 6 pappose setae; ischium unarmed; merus with 2 plumose setae distally and 4 plumose setae medially; carpus with 2 plumose setae laterally, 6 plumose and 1 simple setae medially; propodus with 4 simple setae laterally, 3 pappose setae medially; dactylus with 3 simple setae terminally; exopod as long as basis, basal article with plumose setae, flagellum with plumo-annulate setae ( Fig. 13A ).

Pereopod 1 basis 0.9 length of merus, with 2 pappose setae; ischium broader than long, with 1 plumose and 1 pappose setae; merus with 9 pappose and 1 simple setae; carpus 0.4 merus length, unarmed; propodus 1.5 carpus length, with 1 simple seta; dactylus equal to carpus, with 7 stout simple setae distally; exopod longer than basis and ischium together, basal article with pappose setae, flagellum with plumo-annulate setae ( Fig. 13B ).

Pereopod 2 basis longer than next 2 articles together, with 4 pappose and 4 simple setae medially, 6 pappose setae laterally; ischium with 1 pappose seta; merus with 1 stout microserrate seta and 2 pappose setae distally; carpus 0.8 basis length, with 8 stout microserrate setae medially and 2 pappose setae laterally; propodus with 3 simple setae; dactylus 0.3 basis length, with 1 pappose setae and 2 simple setae terminally; exopod longer than basis and ischium together, basal article with pappose setae, flagellum with plumo-annulate setae ( Fig. 13C ).

Pereopod 3 basis longer than all other articles together, with 9 plumose setae; ischium with 1 plumose and 2 annulate setae; merus with 1 annulate seta; carpus with 1 simple, 3 plumose and 2 annulate setae; propodus with 1 annulate seta; dactylus with 2 simple setae terminally; exopod rudimentary, 0.1 basis length, of 2 articles, with simple setae terminally ( Fig. 13D ).

Pereopod 4 basis longer than all other articles together, with 5 plumose and 2 simple setae; ischium with 1 plumose and 2 annulate setae; merus with 1 annulate seta; carpus with 1 simple, 2 plumose and 2 annulate setae; propodus with 1 annulate seta; dactylus with 3 simple setae terminally; exopod rudimentary, 0.1 basis length, of 2 articles, with simple setae terminally ( Fig. 13E ).

Pereopod 5 basis as long as next 4 articles together, with 5 plumose and 3 pedunculate setae; ischium with 2 annulate setae; merus with 1 annulate seta; carpus with 3 annulate and 2 plumose setae; propodus with 1 annulate seta; dactylus with 3 simple setae terminally ( Fig. 13F ).

Telson twice length of pleonite 6,distinct post–anal narrowing, with 8–9 lateral setae with single subterminal setule, 3 simple terminal setae, subequal in length to lateral setae ( Fig. 13G )

Uropod peduncles 3.2 length of pleonite 6, 1.6 length of telson, with 14 medial setae with single subterminal setule. Uropod endopod of 3 articles, 0.8 peduncle length; article 1 longer than articles 2 and 3 together, with 8 medial setae with single subterminal setule; article 2 1.1 length of article 3, with 1 medial seta with single subterminal setule; article 3 with 2 setae with subterminal setule, terminal seta broken. Uropod exopod broken ( Fig. 13G ).

Etymology. The species is named bruunae for the vessel that collected the specimen, the R/V Anton Bruun.

Depth. 5000 m.

Distribution. Deep western south Atlantic, 29°20’S, 36°26’E.

Remarks. The most similar species are Chalarostylis longisetae and C. brenkei , which can be differentiated by the antennule accessory flagellum and uropod peduncle setation. In C. bruunae the antennule accessory flagellum is equal to or longer than the first article of the main flagellum, and the uropod peduncle has 14 setae medially. In comparison, in C. longisetus , the antennule accessory flagellum is shorter than the first article of the main flagellum and the uropod peduncle has nine setae medially. In C. brenkei , the antennule accessory flagellum reaches nearly to the border of the second article of the main flagllum, and the uropod peduncles in the female have 19–20 setae medially.

Figures

FIGURE 12. Chalarostylis bruunae n. sp. Holotype female USNM 389843 A, side view; B, dorsal view of carapace; C, antennule; D, maxilliped 2. Scale bars full body 1.0 mm, all others 0.1 mm.

FIGURE 13. Chalarostylis bruunae n. sp. Holotype female USNM 389843 A,maxilliped 3; B, pereopod 1; C, pereopod 2; D, pereopod 3; E, pereopod 4; F, pereopod 5; G, telson and uropods. Scale bars 0.1 mm.