Rugalucina munda (A. Adams, 1856)

Taylor, John D. & Glover, Emily A., 2019, Unloved, paraphyletic or misplaced: new genera and species of small to minute lucinid bivalves and their relationships (Bivalvia, Lucinidae), ZooKeys 899, pp. 109-140 : 109

Rugalucina munda (A. Adams, 1856) Figs 3 , 5

Lucina (Codakia) munda A. Adams, 1856: 225 not figured.

Type material.

Syntypes: 3 whole shells NHMUK 20140004. H. Cuming colln, collected by Mr Strange. Shell lengths 11.3 mm, 11.2 mm, 10.4 mm. ( Fig. 5 A–H ).

Type locality.

Moreton Bay, Queensland, Australia.

Material examined.

Australia: Western Australia: Parry Harbour, Kimberley (WAM). Broome Bay (WAM). Northern Territory: Darwin, East Point. Gove (NMV), Groote Eylandt G. of Carpentaria (AMS). Friday Island, Torres Strait (AMS). Queensland: Somerset, Cape York (AMS), Port Douglas (16°28'48"S, 145°27'41"E) seaward edge of mangroves (NHMUK). Buchan Point, Cairns (AMS), Port Denison, Bowen (AMS), Seaforth, Mackay (AMS), Yeppoon (AMS), Tin Can Bay, Snapper Point (25°54'12.18"S, 153°00'58"E), mangroves, muddy sand. Moreton Bay, Redland Bay (27°37'03"S, 153°19'06"E), muddy seagrass, 1 m. North Stradbroke Island, near Dunwich, seagrass (27°29'44"S, 153°23'57"E).

Description.

Small, L to 11 mm, sub-circular, posteriorly slightly truncate in juveniles, shallow posterior sulcus, moderately inflated. Shell colour white, internally often yellowish. Sculpture of fine, low commarginal lamellae crossed by low radial ribs which are broader and more prominent towards the anterior and posterior. Radial ribs are slightly fluted where crossed by commarginal lamellae. Lunule elongate, lanceolate, slightly asymmetrical. Ligament internal, short, situated on a broadly triangular resilifer. Hinge: right valve with single, narrow, cardinal tooth, anterior and posterior lateral teeth small; left valve with two narrow cardinal teeth, small anterior lateral and posterior lateral teeth. Anterior adductor muscle scar medium length, detached for ca. 50 % of length. Posterior scar ovate. Pallial line entire, irregularly lobate. Shell margin finely crenulate, with crenulations coarser towards anterior and posterior.

Distribution.

Northern and north eastern Australia.

Habitat.

Intertidal and shallow subtidal muddy sand, nearshore seagrass and mangrove fringe.

Remarks.

Rugalucina munda is closely similar in shell morphology to R. vietnamica and R. angela and we previously confounded the species ( Glover and Taylor 2001). In shell morphology the differences are subtle; R. munda is more ovoid, the radial ribs are finer, and the inner shell margin is less coarsely crenulated compared to R. angela and R. vietnamica . Furthermore, Glover and Taylor (2001: fig. 16) recorded a distributional gap between Australian and Asian records of ' P. vietnamica '. Features of the anatomy and ctenidial bacteria of R. munda from Port Douglas, Qld were described by Glover and Taylor (2001, as Pillucina vietnamica ).

Hedley (1913: 267) recommended that the name Lucina munda be rejected as unrecognisable because at that time type material had not been identified and the original description ambiguous. Later, because the incorrect type material had been isolated in the NHMUK collection the name Lucina munda had been regarded (e.g., Lamprell and Whitehead 1992) as a synonym of Ctena bella (Conrad, 1837). More recent recognition of the original type material (JDT & EAG) showed that Lucina (Codakia) munda (syntypes figured here for the first time from the Cuming collection and collected in Moreton Bay by Mr Strange) is a species similar to Rugalucina vietnamica and R. angela . In his description Adams (1856) highlights the dichotomously radiating ribs and the radially grooved inner shell margin and the yellowish shell interior. Rugalucina munda is thus the earliest name for the Australian species.

Figures

Figure 3. Internal drawings of left valves of Rugalucina and Pusillolucina species. Not to scale.

Figure 5. Rugalucina munda (Adams 1856). A-H Syntypes Lucina (Codakia) munda A. Adams, 1856 (NHMUK 20140004) Moreton Bay, Queensland, Australia A-C exterior and interior of left and right valves, syntype A, L 11.3 mm D, E exterior of left valve and dorsal view, syntype B, L 11.2 mm F-H exterior of left valve and interior of left and right valves, syntype C, L. 10.4 mm I, J Rugalucina munda exterior of left valve and interior of right valve, Redland Bay, Moreton Bay, Queensland (NHMUK 20191073), L 6.8 mm K-N R. munda Tin Can Bay, Queensland (NHMUK 20191074) K Exterior left valve, L 6.9 mm L interior of right valve, L 6.3 mm M interior of left valve, L 5.5 mm N exterior of left valve, L 6.7 mm O-S R. munda Port Douglas, Queensland (NHMUK 20191085) O exterior of right valve, L 6.5 mm P exterior of left valve, L 4.8 mm Q, R interior of right and left valves, L 7.2 mm S dorsal view, L 5.5 mm.