Thrombasia evalina Kilgallen & Lowry 2014, sp. nov.
Creators: name: Kilgallen, N. M.
name: Lowry, J. K.
Publisher: name: Zenodo
Year: 2014
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Lysianassidae
Thrombasia
Thrombasia evalina

description: Thrombasia evalina sp. nov.
(Figs 14–16)
Types. Holotype female, 9.8 mm, AM P.69059, from east of Broken Bay, New South Wales, Australia (33°37’S 152°04’E to 33°39’S 152°02’E), 896–923 m, dredge, 10 December 1980, R. T. Springthorpe, FRV Kapala stn K80- 20-09. Paratypes: 1 male, 10.2 mm, AM P.69060; 2 specimens, 8.0– 8.8 mm, AM P.69061, same collection details as holotype.
Additional material examined. 2 specimens, AM P.69062, from north-east of Port Jackson, New South Wales, Australia (33°41'S 152°00'E to 33°44’S 151°57’E), 820–888 m, beam trawl, 11 February 1986, R. T. Springthorpe, FRV Kapala stn K86-01-07; 1 specimen, AM P.69058, from east of Broken Bay, New South Wales, Australia (33°31’S 152°08’E to 33°33’S 152°07’E), 914 m, 2.5 m sled dredge, 10 December 1980, R. T. Springthorpe, FRV Kapala stn K80-20-08.
Type locality. Australia, New South Wales, east of Broken Bay (33°37' S 152°04' E), 896–923 m.
Etymology. Named for schooner Evalina lost in 1871 on route between Sydney and Port Stephens; used as a noun in apposition.
Description. Based on holotype, female, 9.8 mm, AM P.69059. Head lateral cephalic lobe subtriangular, apically subacute. Antenna 1 accessory flagellum forming cap partially covering callynophore; primary flagellum with strong 2-field callynophore, robust setae absent from proximal articles; calceoli absent. Antenna 2 peduncular articles 3–5 not enlarged, articles 4–5 with weak brush setae on anterior margin; calceoli absent. peduncular articles 3–5 enlarged, article 4 slightly enlarged; articles 4 and 5 with weak brush setae; flagellum long, calceoli present. Labrum, epistome and upper lip separate; epistome less produced than upper lip, straight; upper lip produced, strongly rounded apically. Mandible molar columnar, with oval fully triturating surface. Maxilla 1 outer plate setaltooth 7 cuspidate distally; palp distal margin with apical robust setae. Maxilliped outer plate with one slender and one broad apical robust setae.
Pereonites 1–7 dorsally smooth. Gnathopod 1 subchelate; coxa reduced, significantly shorter than coxa 2 (~ 50%), tapering distally; basis densely setose along anterior margin; carpus long, longer than propodus, without posterior lobe; propodus small, margins subparallel, sparsely setose along posterior margin, palm moderately acute, entire, straight. Gnathopod 2 propodus palm transverse, slightly convex. Pereopod 5 basis longer than broad, not posteroproximally excavate, posterior margin not serrate. Pereopod 7 basis posterodistally produced less than halfway along merus.
Pleonite 3 without mid-dorsal carina, not produced dorsodistally. Epimeron 3 posterior margin smooth, posteroventral corner broadly rounded. Urosomite 1 not projecting over urosomite 2. Uropod 2 inner ramus with constriction. Uropod 3 stout; inner and outer rami well developed, outer ramus article 2 short, without plumose setae. Telson moderately cleft, with 3 dorsal robust setae per lobe and 1 apical robust setae on each lobe.
Sexually dimorphic characters. Based on paratype, male, 10.2 mm, AM P.69060. Antenna 1 calceoli present. Antenna 2 peduncular article 3 enlarged, article 4 slightly enlarged; articles 4 and 5 with weak brush setae; flagellum long, calceoli present. Uropod 3 rami with dense plumose setae.
Habitat. Not recorded.
Depth range. 820–923 m (this study).
Remarks. Thrombasia evalina appears to be quite similar to T. rotundata (K.H. Barnard). Although that species is poorly described, it shares a number of characters in common with T. evalina, notably the shortened and strongly tapering gnathopod 1 coxa and the distinctly subchelate gnathopod 2. However, the epimeron 3 posteroventral corner of T. evalina is much more broadly rounded than that of T. rotundata and the gnathopod 1 palm is straight in T. evalina but slightly convex in T. rotundata.
Distribution. Tasman Sea. Coast of New South Wales, Australia (this study).
description: Published as part of Kilgallen, N. M. & Lowry, J. K., 2014, The Tryphosa group (Crustacea: Amphipoda: Lysianassoidea: Lysianassidae: Tryphosinae), pp. 501-545 in Zootaxa 3768 (5) on pages 525-528, DOI: 10.11646/zootaxa.3768.5.1, http://zenodo.org/record/4909684