Latreillia elegans Roux, 1830

Castro, Peter, Williams, Austin B. & Cooper, Lara L., 2003, Revision of the family Latreilliidae Stimpson, 1858 (Crustacea, Decapoda, Brachyura), Zoosystema 25 (4), pp. 601-634 : 611-613

Latreillia elegans Roux, 1830

( Figs 3B ; 5 )

Latreillia elegans Roux, 1830 : pl. 22, unnumbered page. — Monod 1956: 78 (references). — Manning & Holthuis 1981: 25. — Rice 1982: 205. — Williams 1982: 238, figs 3b, 8 (synonymy and references). — Debelius 2001: 95 (unnumbered colour photograph). Latreillia manningi Williams, 1982: 233 , figs 1b, c, 2a- e, 3a, 8 (synonymy and references). — Williams 1984: 262, fig. 194a-d. — Manning & Chace 1990: 44. — Guinot 1991: figs 6-8.

Latreillia elegans elegans – d’Udekem d’Acoz 1999: 34, 41, 187 (references). — Türkay 2001: 290.

Latreillia elegans manningi – d’Udekem d’Acoz 1999: 41.

TYPE MATERIAL. — Holotype of L. elegans : 1 ♀ 13.9 × 6.9 mm, Sicily, Cabinet P. Roux (RMNH D 42204; see Fransen et al. 1997: 81).

Holotype of L. manningi : 1 ♂ 9.8 × 5.0 mm, State University of Iowa Bahama Expedition, stn 52, American Shoal Light, Florida, 192-201 m (USNM 5707).

Paratypes of L. manningi : 1 ♂ 6.5 × 3.5 mm, off La Habana, Cuba, 234 m (USNM 21697); 1 ♂ 6.7 × 3.5 mm, 3 ♂♂, 4 ♀♀, Nantucket Shoals, 39°54’N, 69°51’W, 241 m (USNM 19296), plus 3 other specimens, 1 ♂, south of Cape Lookout, 34°39’N, 75°33’W, 193 m (USNM 21698), 2 ovig. ♀♀, off Key West, 24°19’N, 81°39’W, 216 m (USNM 55989), 1 ♀, same as holotype, (USNM 172323). Contrary to Williams’ (1982: 237) indication, no paratypes are deposited at RMNH.

TYPE LOCALITY. — Italy, Sicily.

MATERIAL EXAMINED. — Adriatic Sea. Off southern Italy, 42°32’N, 17°10’E, 2 ♂♂, 1 ovig. ♀ (USNM 15218).

Sicily. 1 ovig. ♀ (USNM 152219).

Algeria. 1 ♂ (MNHN-B 16554).

Western Sahara. Talisman , stn 66, 26°13’N, 17°10’W, 175 m, 8.VII.1883, 1 juv. ♀ (MNHN-B 16555).

Cape Verde Islands. Talisman , off La Praya, 229 m, 23.VII.1883, 1 juv. ♂, 1 juv. ♀ (MNHN-B 16556).

St Helena. Dredging 6, 1 ♂ (MNHN-B 17838).

Eastern United States. Fish Hawk, Nantucket Shoals, 39°54’N, 59°51’W, 241 m, 8.IV.1885, 1 ♂ (USNM 19296). — South of Cape Lookout, 180-260 m, 1 ♂ (USNM 51060). — Off Key West, 24°17’N, 81°58’W, 238 m, 14.II.1902, 1 ♂ (USNM 67740).

Straits of Florida, 25°15’N, 79°15’W, 236 m, 30.I.1964, 1 juv. ♂ (USNM 136827).

Cuba. Albatross, stn 2320, off La Habana, 23°10’N, 82°18’W, 234 m, 17.I.1885, 1 ♂ paratype (USNM 21697), 1 ♂ paratype of L. manningi (USNM 19296). pace without spine (see Rathbun 1937: fig. 18) except in some juveniles and small individuals. Gastric region slender, length 0.4 or more of carapace length. Supraocular spines shorter or slightly longer than ocular peduncles. Hepatic swellings rarely topped by spine. Merus of each third maxilliped sometimes with obtuse tubercle or acute spine on ventral surface ( Fig. 3B ). Abdomen of adult males with all somites distinct; middorsal protuberance on somite 1, acute spine on somite 2 (see Williams 1982: fig. 1c, as L. manningi ). Abdomen of adult females with middorsal protuberance on somite 1, acute spine on each somite 2, 3; somites 4-6 broad, fused with proximal spines laterally near articulation with somite 3 (see Williams 1982: fig. 2e, as L. manningi ), sometimes with midlateral pair on fused somite 5 in largest females. Propodus of each last pair of walking appendage (P5) shorter than carpus; dactylus forming subchela when flexed on distal portion of propodus; propodus with five or six movable spinules (see Williams 1982: fig. 2c, as L. manningi ).

D

IAGNOSIS

.

—

Dorsal

surface

of

gastric

region

of

cara-

DISTRIBUTION. — Mediterranean Sea, eastern Atlantic Ocean (from the Azores and Portugal to Cape Verde Islands), western Atlantic Ocean (from New England to Venezuela), and from Ascension and St Helena islands in the South Atlantic ( Fig. 5 ). Depth: 35- 474 m ( Williams 1982).

Colour: Longitudinal red-brown bands on carapace; red-brown and yellow rings on pereopods and ocular peduncles ( Zariquiey Álvarez 1968: 307). Williams (1982: 239) summarized descriptions of similar colour patterns. Debelius (2001: 95) gave a colour photograph.

REMARKS

Williams (1982) separated the western Atlantic populations previously considered L. elegans as

a distinct species, L. manningi Williams, 1982 .

Both species were found to be morphologically identical and several potential differences were ultimately shown to overlap among the populations. The only exception was the relative length of the pereopods, which was shown to be significantly longer in relation to carapace length in the eastern Atlantic than in the western Atlantic populations ( Williams 1982: 238). Specimens from Ascension Island, nearly halfway between the two populations, were considered as intermediate between the two species. As in the other species of Latreillia , the ratio between the somites of the pereopods is a highly variable character, and thus not a very reliable character. D’Udekem d’Acoz (1999) ultimately treated the two geographical variants of L. elegans as different subspecies. The differences between the two populations are thus seen as minor and overlapping and do not warrant the separation of L. elegans into two separate species.

Besides their geographical distribution, the only clear difference between L. elegans and L. metanesa of the Indo-west Pacific, is the rare presence of a dorsal spine in L. elegans . A dorsal spine was observed only once, in a juvenile male (4.5 × 2.4 mm, MNHN-B 16556) from the eastern Atlantic. The specimen also had a branchial spine on each branchial region of the carapace, a characteristic of juveniles in other species of Latreillia . None of the five smallest specimens in the material identified as L. manningi (= L. elegans ) by Williams (1982: 237) had a spine. Three small males (6.4 × 3.2 mm, USNM 67740; 6.5 × 3.5 mm, USNM 21697; 6.7 × 3.5 mm, USNM 19296) had a smooth carapace. One male (5.2 × 2.6 mm, USNM 51060) had a dorsal prominence but no spine, and a juvenile male, the smallest individual (3.5 × 1.7 mm, USNM 136827), branchial spines and a dorsal prominence but no dorsal spine. In L. metanesa specimens within this size range, and, most importantly, specimens having branchial spines, do have a dorsal spine.

The analysis of DNA from different populations of L. elegans and L. metanesa may prove to be a more reliable way to show if the two species are genetically distinct. It should also determine the genetic distance between the populations of L. elegans on both sides of the Atlantic.

Size

Maximum size: ♂ 14.3 × 8.8 mm, ♀ 12.9 × 7.5 mm ( Williams 1982).

Figures

FIG. 3. — Scanning electron micrographs of right third maxillipeds; A, Eplumula australiensis (Henderson, 1888), station data unrecorded; B, Latreillia elegans Roux, 1830, Massachusetts, station data unrecorded; C, Latreillia metanesa Williams, 1982, New Caledonia, CHALCAL 2, stn DW 83, 200 m, juv. ♀ 7.5 × 4.4 mm (MNHN-B 28131); D, Latreillia valida de Haan, 1839, Philippine Islands, station data unrecorded.

FIG. 5. — Geographical distribution of Latreillia elegans Roux, 1830 (•) and L. williamsi Melo, 1990 (•).