Bogidomma, 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 : 68-69

Bogidomma n.gen.

Etymology. Named for the presence of eyes, unique among the family.

Type species. Bogidomma australis n.sp.

Diagnosis. Body: pleonite 6 naked, rostrum obsolescent, lateral cephalic lobes strongly projecting, broad, with slight antennal sinus present; tending vermiform. Urosome without armaments. Head: first antenna moderately elongate, longer than antenna-2, ratio of peduncular articles 2:2:1, accessory flagellum 2-articulate; second antenna, shorter than AI, flagellum much shorter than peduncle, calceoli absent. Mandibles: palp 3-articulate, ratio of articles 4:11:6, article-l not setose, article-2 with few setae, article-3 with 2 E-setae only. Lower lip: broad, inner lobes elongate. Maxillae: without pubescence or peripheral setae except a single mid-medial seta on the inner plate of the second maxilla; inner plate of the first maxilla ovato-rectangular to subrectangular, without setae or pubescence, bearing 6 or 7 terminal spines, palp of two articles, with thin apical spines. Coxae: 1-7 short, longer than broad, coxae 1-2 lacking posterior spines, coxa 1 not expanded below, coxa 4 not excavate posteriorly, subquadrate, coxae 4-5 of approximately equal length. coxae 3-7 each with single posterior spines, coxae 1-4,6 each with single anterior spines. Gnathopods: similar. First gnathopod: dominant, hand ovate, carpus much shorter than propodus, strongly lobate, merus posteriorly extended but without hyaline lobe, palm strongly oblique, palmar spines not symmetrically bifid but with small trigger like extensions, spines at corner of palm; 2 long, lateral, 1 moderate medial; few simple setae along the palm; dactyl not reaching the end of the palm. Second gnathopod: smaller than gnathopod 1; carpus short, weakly lobate; hand moderately enlarged, ovate, palm acutely oblique, sparsely setulose, irregularly spinose; palm without distinct corner, bearing single slender medial and lateral trigger spines at point of intersection of dactyl. Pereopods: 6-7 moderately elongate, pereopod 7 longer than pereopod 6, pereopod 7 article-2 moderately expanded and posteriorly extended but lacking a posteroventral lobe; dactyls of pereopods 3-7 with 1 or 2 accessory spinules. Gills: coxae 4-6 each with a flask shaped gill; gill 6 not reduced; sternal gills absent. Oostegites: coxae 2- 5 each with an elongate, thin, poorly setose oostegite. Uropods: uropod 3 extended beyond uropods 1-2 in entire animal, outer ramus with 1 article only, inner rami of equal length. Telson : broader than long, uncleft, laterally convex and terminally concave, subapical spines and paired penicillate setules on either lobule at MO.85.

Additional description. Upper lip: symmetrical, laterally and distally setose, weakly excavate below. Mandibles: accessory blades (rakers) few (3), with no inter-raker plumose setae, but a few additional plumose setae basal to the molar. Maxilliped: both plates short, inner plate bearing 3 long distal setae and 2 blunt naked tooth spines, but no other setae or pubescence; outer plate bearing 4 distal setae and a single medial seta at MO.5, medial margin otherwise without sinuosities, setae or pubescence; palp long, articles 2-3 weakly setose medially, naked laterally, article-3 with a single comb row of fine setae at base of dactyl, few distomedial setal-spines, apex not produced; dactyl unguiform with an oblique row of comb setae, a slender, elongate nail and pair of terminal spines one of which is equal to the nail. Gnathopods: dactyls of gnathopods 1-2 without recumbent inner tooth spine, lacking nail; gnathopod 1 without rastellate seta of article-4. Pereopods: 3-4 smaller than pereopods 5- 7; posterior spine sets of article-6 of pereopods 3-4 evenly spaced. Pleopods: similar, peduncles devoid of setae, each with a single outer ramus, no setae bifid; each peduncle with 2 retinaculae, no accessory retinaculae. Epimera: Post-ventral tooth of epimera 1-3 absent, posterior margins without spines or setae, smooth, slightly convex. Uropods: apicolateral corners of peduncles of uropods 1-2 with small single spines, dorsal margins without spines except for 1 medium size mid-dorsal spine at MO.85 on uropod 1; medial margin of uropods 1-2 with 1 apical spine; rami of uropods 1-2 subequal, without spine rows; uropod 1 without basofacial spine; uropod 3; medial setae of outer ramus absent; peduncle with 1 medial subdistal and 1 apicolateral spine. Urosome: ventrodistal spine on urosomite 1 at base of uropod 1 absent.

Relationship. This genus is unique among recorded bogidiellids in possessing well-developed eyes. All previously recorded bogidiellids are without eyes ( Stock, 1984). Except in the presence of eyes Bogidomma is unequivocally a bogidiellid. Absence of inner rami of the pleopods suggests it is closest to either Bollegidia or Bogidiella .

Bogidiellids are categorised by Barnard & Barnard (1983) as probably a mixture of descendents from various Crangonyctoids. Barnard & Karaman (1980) discussed and dismissed Bousfield's (1977) elevation of the Bogidiellidae to superfamily status pointing out that the only consistent characteristic of the group is the dominant first gnathopod, a common occurrence among many groups, and therefore no basis for allocation to superfamily. Stock (1981) and subsequent authors have retained family status for this loose group characterised by a number of features which, however, do not all occur in all genera. Stock's (1981) cladistic analysis of the then known genera and species of the family translates into a position for Bogidomma australis somewhere within the Bogidiella group of subgenera, or possibly, though more remotely, on the basis of configuration of the lobes of the maxilliped, with Marigidiella (split from Bogidiella ), although the new genus is unlike it in possessing two elements to the palp of the first maxilla, as well as a naked inner lobe and reduced setal cover of the second maxilla. Using the keys of Barnard & Barnard (1983), the new genus fits closely to Bogidiella except for the presence of eyes, ratio of the lengths of peduncular articles of the first antenna and of the length of the primary flagellum of the first antenna.

Geographically bogidiellids have been regarded as primarily Neotropical. They have, however, been reported from all the major continents, except Antarctica. The only record of a bogidiellid from Australia is of Bogidiella (Xystriogidiella) capricornea Stock, 1984 , from the tropical marine atoll Heron Island, situated off the Pacific coast, a first recording of the family from the Pacific Ocean. Bogidiella is Palaearctic and Palaeotropical (Oriental) as well as Neotropical ( Hertzog, 1933; Stock, 1983). Stock (1983) considered the distribution of the Bogidiellidae can be explained as the result of the break up of Pangea in the Mesozoic and isolation of populations in the Tertiary, and that the limited distributions and low fecundities of many species indicates their poor dispersive abilities.