Bogidomma australis, Bradbury & Williams, 1996

Bradbury, J. H. & Williams, W. D., 1996, Freshwater amphipods from Barrow Island, Western Australia, Records of the Australian Museum 48 (1), pp. 33-74 : 71-74

Bogidomma australis n.sp.

Figs 22-24

Etymology. The name refers to the type locality region.

Type locality. Cave number WL8, Barrow Island, Western Australia .

Material examined. HOLOTYPE (Western Australian Museum WAM 8-96) Barrow Island, Western Australian Museum collection BES799, female 2.8 mm collected 2 December 1992. Other specimen: BES716 female "t" 2.5 mm (broken) collected 28 November 1992.

Diagnosis. As in the genus.

Description of holotype (male). Body (Fig. 22) 2.8 mm; urosome without armaments, length 2.5-3 mm. Head: rostrum absent; eyes present, large, about 0.3x head, ovate, pale and indistinct in the preserved specimen; antennal sinus absent except for a small concavity of the ventral lateral cephalic lobes. First antenna (Fig. 22): length O.4x body, 1.5x antenna-2; primary flagellum of 6 articles, shorter than peduncle (120:200); peduncular articles 1 and 2 equal, article-3 shortest, setae sparse; primary flagellum with aesthetascs but without calceoli, article-3 smallest, remainder of uniform length, sparsely setulate; accessory flagellum 2-articulate, (Fig. 22) extending to MO.l of the third article of the primary flagellum; second article tiny (1:8), articulated subdistally and extending only 0.4 of its length beyond the terminus of the first. Second antenna (Fig. 22): short, length 0.3x body, peduncle much longer than flagellum (195:35), articles 4-5 longest, articles 3-5 with weak ventral setation and a weak single mid-dorsal seta; article-4 with proximal and mid-dorsal setae; flagellum of 5 articles of progressively reduced length, all articles with weak dorsal setation; calceoli absent. Upper lip (Fig. 22): symmetrical, laterally and distally setose. Mandibles (Fig. 22): similar; palp 3-articulate, article-l short, ratio of article lengths 4:11:6, article-3 with 2 apical setae (2E) only, incisor 4 toothed, lacinia mobilis bifid, with 3 setose accessory blades, and a short row of 3 plumose setae leading to the molar; molar indistinct, weakly or non-triturative, bearing distal plumose seta; no other pubescence. Lower lip (Fig. 22): outer lobes finely pilose apically, spread broadly by forward intrusion of elongate inner lobes; inner lobes naked, projecting beyond outer lobes, relative lengths; 33:23. First maxilla (Fig. 22): first maxilla asymmetric; palps of two articles, left palp with 3 apical spines, right palp with 2; left outer plate with 5 denticulate spines and 1 or 2 naked spines all of approximately equal length, right outer plate with 3 short denticulate spines, 1 short and 3 long curved, naked spines. Second maxilla: both plates without pubescence, asymmetric; left inner plate bearing 4 blunt apical spines and 2 short distomedial spines; right inner plate bearing 3 apical and 2 subapical slender, sharp spines, and an elongate slender distomedial spine which extends as far as the longest apical spines. Maxilliped (Fig. 22): palp article-3 with 3 distal and 3 apical spinesetae, nail of dactyl slender, with 2 subterminal setae, the longer extending as far as the nail itself; article- 3 with a transverse comb-row of setae basal to the dactyl, the dactyl with basal setae and an oblique row of similar setae, as well as a single dorsal setule at MO.2. First gnathopod ( Fig. 23 ): dominant, 1.5x gnathopod 2; article-4 posteriorly linear, carpus strongly lobate, propodus ovate, much longer than broad, tapering apically, posterior edge naked except for a single distal submarginal spine at MO.7; corner of palm recurved with 2 lateral and 1 medial spines, palm convex, finely serrated, spines and setae all submarginal, dactylus not reaching end of palm. Second gnathopod ( Fig. 23 ): smaller than gnathopod 1; hand ovate, elongate, width 0.3x length; palm finely serrated, convex except at the posterior end where it is broadly sinuous, palmar spines and setae all submarginal, spines not symmetrically bifid but with triggers; dactyl not reaching palmar corner, which is marked by a pair of slender trigger spines with a further slender spine posteriorly; hand facially and posteroventrally pubescent; carpus posteriorly pubescent; coxal plate subequal to coxa 1 with a single anteroventral spine. Pereopods ( Fig. 23 ): pereopods 3-4 shorter than gnathopod 1, pereopod 3 longer than gnathopod 2, pereopod 4 subequal to gnathopod 2, pereopod 3 longer than pereopod 4, pereopods 3-4 articles 1-5 sparsely setose posteriorly and anteriorly, posterior margin of article-6 on pereopods 3-4 with armament formula SS-S-Ss and S-S-S-S, thus with only 1 locking spine; pereopods 6-7 similar but consecutively elongate, with 2 locking spines on pereopod 6; article-2 of pereopod 7 weakly expanded, but not posteriorly lobate, without posterior setae; article-2 of pereopod 6 not expanded with few posterior setae; dactyls of pereopods 3,4,6 bearing 2,2,1 accessory spinules. Gills (Fig. 24): of coxae 4-6 flask shaped, of coxa 6 not reduced. Oostegites (Fig. 24): strap like, length O.5x article-2 of pereopods, bearing few distal setae. Pleopods (Fig. 24): similar. Retinaculae 2 per pleopod without accessory, peduncles without setae, each uniramous, the outer ramus only present, of 3 articles, each article with 2 plumose setae, none bifid. Epimera (Fig. 24): epimera 2-3 post ventrally quadrate, epimeron 3 slightly extended, epimeron 1 more rounded, subquadrate; posterior margins slightly convex, smooth, without setae or spines, without a lateral ridge. Pleon (Fig. 24): only pleonites 2-3 with a single posterior dorsolateral seta on either side; posterior margins of 1-3 convex, remainder linear, all smooth, without setae or teeth except as above. Uropods (Fig. 24): uropod 3 longest, extending beyond uropods 1-2 in the entire animal; uropod lengths relative to uropod l-uropod 2 = 0.75, uropod 3 = 1.3; peduncle length of uropod 1 = 1.3x inner ramus, outer margin with 1 small apicodistal spine, inner apical margin with a single, longer spine, without dorsal spine rows except for a single mid-dorsal spine at MO.85; rami of subequal length, lacking marginal spines; terminal spines = 5 lateral, 4 medial, the basal pair on each displaced subapically: uropod 2 peduncle length equal to length of inner ramus; peduncle naked except for a single apicomedial and a smaller apicolateral spine; outer ramus O.9x inner; both rami without marginal spines, terminal spines = 4 lateral, 5 medial, several displaced subapically; uropod 3 rami equal in length; peduncle length O.85x rami, 3x urosomite 3, bearing a single long apicolateral spine, and single smaller, apicomedial spine (the medial apex rounded, not subquadrate as is the lateral, thus displacing the apical spine subapically); outer ramus bearing a single laterofacial spine at MO.3 and 5 terminal spines; inner ramus bearing a row of 3 dorsomedial spines and 5 terminal spines. Telson (Fig. 24): width 1.8x length, approximately equal to, urosomite 3, not cleft, the apex concave to MO.9; 1 large trigger spine and 1 smaller spine submarginal, subapical on either lobe; paired penicillate setules at MO.85 on either side, submarginal on the left side.

Distribution. Barrow Island, Western Australia, in cave.

Figures

Fig. 23. Bogidomma australis holotype female 2.8 mm. Legs.