Lamarckdromia excavata ( Stimpson, 1858 ) Stimpson, 1858

Mclay, Colin L. & Hosie, Andrew M., 2022, The sponge crabs of Western Australia and the Northwest Shelf with descriptions of new genera and species (Crustacea: Brachyura: Dromiidae), Zootaxa 5129 (3), pp. 301-355 : 333-336

Lamarckdromia excavata ( Stimpson, 1858) comb. nov.

( Figs. 22 , 23 )

Dromidia excavata Stimpson, 1858 , 239.

Dromia ciliata Henderson, 1888: 3 , pl. 1 fig 1–1c.

Dromia excavata . —Haswell, 1882: 140.

Dromidiopsis excavata . — Rathbun, 1923a: 146, pl. 38.— Hale, 1927: 110, fig. 106; 1941: 281, figs. 15–16.

Dromidiopsis globosa . — McLay, 1993: 135.— Davie, 2002: 163.

Lamarckdromia globosa . — Guinot & Tavares, 2003: 70, fig. 10A–D.— Poore, 2004: 306, figs. 85b, 86c, pl. 18a, b.— Ng et al., 2008: 34 (list).

Material examined. Western Australia: WAM C6340 , Point Peron , 3-06-1947, coll. C. Orten: male 52.5 × 48.2 mm (sponge cap); WAM C17533, W of Shoal Point , 73 m, 28°99’00”S, 113°51’00”E, coll. FRV Diamantina , 73 m, 5-12-1970: female 34.0 × 30.0 mm. WAM C20822, west end of Rottnest Island , February 1991: male 41.8 × 35.7 mm; WAM C43589, Denmark Beach , washed ashore, 2009: damaged female 31.8 × 29.2 mm; WAM C51135, Woodside Kimberley Survey 2012, stn. 1001K 12, 15 Oct, 2012, subtidal: female 13.8 × 14.7 mm, carrying a sponge Cinachyrella tenuiiviolacea ; AM G5306 , Western Australia, male 43.4 × 39.7 mm; AM P8224 , Western Australia, female 40.1 × 38.0 mm (dry). Bass Strait: AM E1339 , Bass Strait , ovig. female 35.7 × 36.5 mm, 150 eggs, diameter 1.9 mm (specimen reported by Rathbun, 1923) .

Description, Carapace width similar to carapace length in small specimens, ranging up to approx. 1.1 × cl in adults. Surface smooth, strongly convex, covered by short setae with fringe of longer setae across anterior margin. Frontal area steeply vaulted, short median groove from rostrum separates pair of gentle epigastric swellings; frontal fringe following edge of vault. Branchial groove deeply marked; mid-way on anterior side with pair of deep pits; groove connecting with deep lateral cardiac groove; anterior cardiac border marked by shallow lunate groove; intestinal area, posterior to cardiac area, deeply sculptured with ridges arranged in face-like manner; posterior carapace margin deeply concave. Rostrum tridentate, teeth well developed, sub-acute, similar size, lateral teeth directed horizontally, median tooth on lower level, slightly deflexed. Supraorbital tooth small blunt, postorbital tooth similar, suborbital margin with prominent blunt tooth visible dorsally between supra- and postorbital teeth. Anterolateral carapace margin obtuse, slightly convex followed by concave section ending at widest point, shoulder-like without distinct tooth; sub-hepatic area deeply excavated, slightly visible dorsally, lower margin prominent, obtuse, curving upward to meet shoulder. Posterior to widest point, carapace margin convex, interrupted by branchial groove without tooth.

Cheliped (P1) well developed, densely covered by short setae, surface mostly smooth, superior distal corner of carpus armed with acute spine; propodus inflated, smooth except for row of 6 or 7 large sub-acute tubercles distributed along inner superior border; fingers down-curved, gaping, armed with 6 or 7 occlusal teeth, hollowed out internally, interlocking at tips.

P2 and P3 densely covered by short setae, smaller than P1, dactylus armed with 3 or 4 short spines ventrally; P4 and P5 reduced, P4 shortest, P5 sub-dorsal, both sub-chelate. Short curved dactyli opposed by stout spine with 3 or 4 short distal propodal spines on outer margin; P5 with small proximal spine on the outer margin of dactyl. Crista dentata on third maxillipeds armed with 12 or 13 small stout spines. Female sternal grooves 7/8 convergent, terminating as spermathecal apertures on small swelling between coxae of P2. Structural details of male and female sterna and abdominal retaining mechanism as figured by Guinot and Tavares (2003: fig. 10A–D; male 24 × 25 mm, female 25 × 25 mm, MNHN-B22041, as “ L. globosa ”).

Telson posterior margin convex, uropods vestigial, hidden ventrally in joint between telson and abdominal segment 6. Terga of male abdominal segments sculptured, with deep concavities on each side. Male G1 stout, semirolled tube, tip setose; G2 styliform, much longer than G1.

Remarks. Since revision of Dromidiopsis by McLay (1993) Dromidia excavata Stimpson, 1858 from Sydney Harbour (Port Jackson) has been known as Dromidiopsis globosa ( Lamarck, 1818) . Haswell (1882) had suggested that the “closest ally” of Dromia excavata was Dromia globosa Lamarck, 1818 . The descriptions given by the authors of these species were brief, but De Man (1887: pl. 18 fig. 1A, B) provided an illustration of a presumed lectotype (MNHN-B22033, male damaged, locality unknown). Milne Edwards (1837) gives the size as CL = 21.1 mm. However, close comparison of our L. excavata specimens with De Man’s figure of the type in Paris (see below) show that they differ from L. globosa and are not synonymous as had been assumed. While the overall conformation of the anterior half of the carapace of L. globosa (the part illustrated by De Man, 1887) is similar, the sub-hepatic area is much more exposed in dorsal view and there is a strong anterolateral tooth near the widest point, a feature not shared by either of the Australian species dealt with herein (see 2). De Man’s figure of L. globosa also shows the right cheliped with 3 or 4 distinct tubercles along the dorsal margin of the propodus and a distinct tubercle on the superior distal corner of the carpus. Both of these characters are found in D. excavata but not in L. beagle sp. nov. Therefore, we conclude that there are three species of Lamarckdromia : L. beagle sp. nov., L. excavata and L. globosa , but only the first two are known to occur around Australia. The distribution of L. globosa is unknown. Hale (1927) said that in live L. excavata the carapace setae are pink.

Distribution. Australian endemic: New South Wales, South Australia, Tasmania, Victoria and Western Australia. Depth 30– 180 m.

Figures

FIGURE 22. Lamarckdromia excavata (Stimpson, 1858) comb. nov. A–C, female 34.0 × 30.0 mm (WAM C17533): A, view showing fringe along front of carapace; B, frontal view; C, ventral view. D–F, male, 41.8 × 35.7 mm (WAM C20822): D, view showing fringe along front of carapace; E, frontal view with sponge cap; F, ventral view.

FIGURE 23. Lamarckdromia excavata (Stimpson, 1858) comb. nov., male, 52.5 × 48.2 mm (WAM C6340): A, dorsal view right half of carapace; B, dorso-frontal view of carapace and cheliped; C, frontal view cheliped and hepatic area of carapace; D, fronto-dorsal view of carapace and cheliped.