Brevisomabathynella pilbaraensis, Cho & Humphreys, 2010

Cho, Joo-Lae & Humphreys, W. F., 2010, Ten new species of the genus Brevisomabathynella Cho, Park and Ranga Reddy, 2006 (Malacostraca, Bathynellacea, Parabathynellidae) from Western Australia, Journal of Natural History 44 (17 - 18), pp. 993-1079 : 1056-1061

Brevisomabathynella pilbaraensis sp. nov.

( Figures 38–40)

Material examined

Holotype (adult male), allotype (adult female), paratype (adult male). Holotype: dissected on five slides ( WAM C 40297 ) . Allotype: dissected on five slides, same data as for holotype except Bore near W126 (23°13′ S, 119°53′ E), BES 3574 ( WAM C 40298 ) . Paratype: as a whole specimen in a slide, same data as for holotype except Bore near W120 (23°13′ S, 119°53′ E), BES 3527, ( WAM C 40299 ) .

Type locality

Australia, Western Australia, Pilbara, Ethel Creek , Bore W 230 (23°13′ S, 119°54′ E), BES 3468, 11 November 1998, leg. S.M. Eberhard.

Description of adult male (holotype)

Body. Length 1.32 mm. Head as long as anterior three thoracic segments 1–3 combined, approximately 11 times as long as wide ( Figure 38A).

Antennule ( Figure 38B). Seven-segmented. First segment with one seta on inner margin, with two simple dorsal setae and with one dorsal, one ventromedial and two lateral plumose setae. Second segment with one group of four plumose setae and with three simple setae on inner margin. Third segment with two lateral setae including one plumose seta and three setae on inner margin. Inner flagellum of third segment with three simple setae. Fourth segment with one stub seta and one plumose seta on dorsal margin, and with two stub setae and two plumose setae on outer distal apophysis. Fifth segment with three simple setae and one plumose seta. Sixth segment with four setae on inner margin and with dorsal group of two aesthetascs, one simple seta and one additional aesthetasc lateral to simple seta. Middle part of aesthetascs barely reaching seventh segment. Seventh segment with three subterminal aesthetascs and four simple setae.

Antenna ( Figure 38C). Five-segmented, as long as antennular segments 1–3 combined. Fourth segment slightly shorter than fifth segment and slightly thicker. Setal formula: 0+0/0+0/1+1/1+1/4(1). Plumose seta of distal segment shorter than longest simple seta.

Labrum ( Figure 38D). Flat, with eight teeth of more or less similar size flanked by five teeth decreasing in size laterally on each side. Ventral surface with four pair of teats and numerous combs of ctenidia.

Mandible ( Figure 38E,F). Incisor process of four teeth. Tooth of ventral edge triangular. Spine row consisting of five spines. Palp of one segment, with one apical seta.

Maxillule ( Figure 38G). Two-segmented. Proximal segment with four setae on inner margin. Distal segment with two terminal spines, with three spines with denticles and with three simple setae of different size on outer margin.

Maxilla ( Figure 38H). Four-segmented, setal formula 3-4-7-8.

Thoracopods I–VII ( Figures 39 A–D, 40A–C). Thoracopods I–IV increasing in size posteriorly. Thoracopods IV–VII similar in size. Thoracopods I–VII each bearing one epipod on protopod. Basipod of thoracopods I–VII with one seta. Number of exopodal segments of thoracopods I–VII: 2-3-3-3-3-3-3. Endopod of thoracopods I–VII four-segmented, setal formulae:

Th. I 1+1/2+1/1+1/3(1)

Th. II–VII 1+1/1+1/0+1/3(1)

Thoracopod VIII ( Figure 38I,J). Rectangular in frontal view, 1.5 times as long as wide. Protopod massive, with prominent penial region. Epipod large, triangular, distal part barely reaching terminal end of penial region. Basipod without setae, inner margin of basipod drawn out into projection. Exopod one-third size of basipod, triangular, with two subterminal setae. Endopod one-half size of exopod, with one terminal seta.

First pleopod ( Figure 38L). Small, in form of two small stubs separated from each other. Each stub bearing one terminal seta.

Uropod ( Figure 39E,G). Six spines of similar size on inner margin of sympod. Exopod as long as endopod, with four setae on outer and terminal margin, without basiventral setae. Endopod 46% as long as sympod, with two dorsal plumose setae near base, with two terminal setae and one subterminal plumose seta on outer margin, and with one terminal, one subterminal and one additional spine on inner margin. Terminal spine somewhat longer than subterminal spine. Inner-marginal spine spike-like, two-thirds as long as subterminal spine.

Pleotelson ( Figure 39E,F). One seta near base of each furcal ramus on both sides. Anal operculum convex.

Furcal rami ( Figure 39E,F). 1.2 times as long as wide, with two large terminal spines, and five smaller spines on inner margin, and with two dorsal setae.

Description of adult female (allotype)

Body. Length 1.35 mm. Identical to male except for following characters.

Thoracopod VIII ( Figure 38K). Conical, half as long as endopod of male thoracopod VIII.

Uropod. Sympod with five spines.

Intraspecific variation

Body length of paratype: 1.31 mm. Paratype does not differ from holotype.

Etymology

The specific name refers to Pilbara, Australia.