Armases roberti (H. Milne Edwards, 1853 )

Parasram, Nadeshinie, Santana, William & Vallès, Henri, 2021, Updated checklist of semi-terrestrial and estuarine crabs (Crustacea: Decapoda: Brachyura) of Barbados, West Indies, Zootaxa 5052 (4), pp. 451-485 : 472

Armases roberti (H. Milne Edwards, 1853)

Fig. 13 A, B, C, D

Sesarma roberti H. Milne Edwards, 1853: 182 .

Sesarma bromeliarum Rathbun, 1896: 143 [type-locality: Rio Cobre (St. Catherine), Jamaica; P.W. Jarvis (coll.); type in USNM 19406 ].

Armases roberti — Abele 1992: 526–527, figs. 23 c, 26 & 27. Schubart & Diesel 1998: 743–750. Diesel & Schuh 1998: 423–436. Ng et al. 2008: 220. Poupin 2018: 227, fig. 260.

Material examined. Barbados, Long Pond , St. Andrew, coastal wetland, 13̊ 15’40.6” N–59̊ 33’22.94” W, 1 ♂; 2 ♀ CW: 12.1; 28.4, 17.8 mm ( BLSZ 001 ) . Barbados, Joe’s River , St. Andrew, freshwater, 13̊ 21’68.55” N–59̊ 52’75.17” W, 1 ♀ CW: 11.6 mm ( BLSZ 076 ) . Idem , 2 ♂ CW: 24.7; 14.4 mm ( BLSZ 075 ) . Idem , 3 ♂ CW: 20.7; 20.3; 17.3 mm ( BLSZ 116 ) . Idem , 2 ♂ CW: 17.6; 15.5 mm, 1 ♀ CW: 21.1 mm ( BLSZ 130 ) . Barbados, Lakes River , St. Andrew, freshwater, 13̊ 14’14.13” N–59̊ 32’45.83” W, 2 ♂, 2 ♀ CW: 3.0; 2.0; 14.6; 22.1 mm ( BLSZ 053 ; MZUSP 40926 ; MZUSP 40890 ) .

Distribution. Armases roberti is found in the Western Atlantic: Cuba, Jamaica, Dominican Republic, St. Thomas, St. Croix, Guadeloupe, Dominica, Martinique, St. Lucia, Barbados, Tobago, and Trinidad ( Abele 1992; Poupin 2018).

Distribution in Barbados. Long Pond, Lakes River, Joe’s River, and Joe’s River Tributary [ Table 1 (Site #s: 3, 4, 6 & 7)].

Habitat in Barbados. On the banks of estuarine streams and ponds on muddy bottoms at depths of ~ 0.5–2 m ( Fig. 2A : A–B).

Ecological notes. This species was collected approximately 150 m from the sea on the branches of trees of Terminalia catappa L. , near the banks of the Long Pond wetland. When approached, the crabs would either leap into the water from the branches or jump onto other branches that were out of reach. At the Lakes River site, Armases roberti were found among dried branches of trees of Terminalia catappa L. , ~ 80 m away from the sea; the crabs appeared to be feeding on green moss. Juvenile and adult crabs were seen at the mouth of the river, where specimens of Armases roberti were collected along with the crayfish Macrobrachium carcinus ( Linnaeus, 1758) and another unidentified crayfish species. At the Joe’s River site, the crabs were collected ~ 84 m from the high-tide mark. Ovigerous females were collected in August 2019 and observed in November 2020. The crabs were active during the daytime periods. All specimens were collected with hand nets ( Fig. 3D ).

Remarks. Specimens of Armases roberti (3 male; 4 female), were collected by the Smithsonian-Hartford Expedition (1937) in Joe’s River; they are stored at the USNM (catalogue # 73317). Although collected in 1937, Armases roberti was reported for Barbados for the first time in 1969 by Chace and Hobbs as Sesarma (Holometopus) roberti . This species is recognized by the absence of setae on the dorsal surface of the carapace and the presence of setae and spines on the dorsal and ventral surfaces of the propodus and dactylus of the walking legs; the fourth pereiopod is longer than the others ( Abele 1992).

Figures

FIGURE 2A. Semi-terrestrial and estuarine habitats of Barbados. A, B, Coastal Wetlands; C, D, Rocky Shores (Photos: N. Parasram).

FIGURE 3. Sampling methodologies used for specimen collection. A, Baited onion bag trap (0.95 m x 0.55 m; mesh size: 0.5 mm); B, Large crab trap (B:1.0 x 0.40 m; mesh size: 50 x 40 mm); C, Small cage crab trap (C: 0.5 x 0.2 m, mesh size: 30 x 15 mm); D, Hand nets (diameter: 60 mm; mesh size: 0.1 mm); E, Fruit bait outside of crab burrow.

FIGURE 13. Habitus of Armases roberti (H. Milne Edwards, 1853) (BLSZ 130). A, B, dorsal view of male and female; C, D, ventral view of male and female. Scale bar: 20 mm.