Decapoda - Brachyura - Portunidae - Thranita

Thranita foresti (Crosnier, 1962)

World Distribution
Apel & Spiridonov (1998 : 241) - For T. foresti - Indo-ouest Pacifique. Golfe Aden, Afrique oriental, Madagascar, Seychelles, Mergui, Andaman, Thailande, Indonésie, Chine, Philippines. Comprend Mayotte, premier signalement. - T. foresti accepted as Thalamita helleri Hoffmann, 1874 in WoRMS (2017) but not in WoRMS (2021): revision of type of T. helleri is needed.
New Caledonia in Spiridonov, 2017: 1223

Environnement : Marine - Substrat/Association : Soft bottom (mud or sand)

Vertical range : Shallow-waters (0-100 m) - Min-Max observed: 0-10 m

Mayotte data
Thranita foresti (Crosnier, 1962)
Thalamita helleri Hoffmann, 1874 - (not T. helleri -> T. foresti, corrected 2021).
Material examined — Mayotte KUW 2009, st. 2, interdital between Trevani beach to Kangani Mangrove, 1 M 28.6 x 41.3 mm MNHN B32482, MNHN-IU-2009-1244, 1 F ov. 20.7 x 30.6 mm MNHN B32498, MNHN-IU-2009-1260, 1 M 21.3 x 31.3 mm, MNHN B32500, MNHN-IU-2009-1262, 1 M juv. 9.4 x 13.1 mm, photo, MNHN B32525, MNHN-IU-2009-1285 (with hesitation, dactyl of P5 blue but male pleopod not strongly curved; ?juvenile aspect); st. 6, Déversoir Badamiers, Petite Terre, 1 M 27.7 x 41.3 mm photo, 1 F juv., 2 juv., MNHN B32481, MNHN-IU-2009-1243, 1 F 31.7 x 47.4 mm (photo 'vert-orange', côte médiane sur la face externe de la paume moins prononcée que chez les mâles) MNHN 32483, MNHN-IU-2009-1245, 1 M, 1 F juv. MNHN B32499, MNHN-IU-2009-1261; st. 20b, Islet M'tzamboro, western reef flat, 10-15 m, 1 F (soft carapace), MNHN B32484, MNHN-IU-2009-1246; st. 26, Mutsumbatsou reeflat, intertidal, 1 M 27 x 39 mm, 1 F ov. 27.4 x 40.4 mm, MNHN B32480, MNHN-IU-2009-1242; st. 29, Mboianatsa beach, Ngouja hotel, littoral, 1 F 17.3 x 26.6 mm, MNHN B32497, MNHN-IU-2009-1259; st. 38, Bay Chiconi/Sada, southwest, coll. Bouchard/Dinhut, 24/07/2008, 1 F juv. 10.4 x 15.4 mm, MNHN B32514, MNHN-IU-2009-1274; st. 39, Sohoa beach, coll. J. -M. Bouchard, V. Dinhut, 01/07/09, 1 M 27.4 x 39.6 mm, MHNN B32479, MNHN-IU-2009-1241. - Mayotte, det. J. Poupin from photo Frédéric Ducarme, May 2018. No specimen examined (typical blue coloration on P5).
Other records — Thalamita foresti - Poupin et al., 2013c: 11, Glorieuses, 1 sp. MNHN-IU-2013-7312, Expedition Glorieuses December 2012 (new record), st. BIO 30, 1 M juv 7.5x10.7 mm (remains of blue coloration on P5 propodus, which is a good diagnostic character for this species).
Remarks — All specimens from Mayotte registered in MNHN collection as Thalamita foresti Crosnier, 1962, a species accepted as Thalamita helleri Hoffmann, 1874 in WoRMS (2018) (see also Appel & Spiridonov, 1998: 241, remarks). - This synonymy no more accepted in WoRMS (2021) - Correction J. Poupin in 2021.
A few specimens were confused on the field with T. crenata that has superficial ressemblances. Thranita foresti has a pilous carapace, 5 subequal spines on carapace anterolateral margin, and tip of male pleopod bent at about 180° (almost straight in T. crenata, see Crosnier, 1962, figs 230-233). On live specimens of T. foresti the dactyl of swimming P5 is remarkably colored in blue, a character that proved very useful to quickly sort the specimens on the field. Another species that can be confused with T. helleri is Thalamita danae Stimpson, 1858 (see Crosnier, 1962; Appel & Spiridonov, 1988).
Geographic and depth ranges — IWP, Gulf of Aden, Mayotte (this work), Mozambique, Madagascar to Philippines, New Caledonia (recently reported in Spiridonov, 2017b, as T. foresti); intertidal, subtidal.

New Caledonia data
Thalamita foresti - Spiridonov, 2017: 1223, 1 female (MNHN, no catalogue number), New Caledonia, Platier de Thio (St. Gabriel), 22.iv.1989

Comment(s) on data
This remark in Apel & Spiridonov (1998: 241) : Hoffmann (1874) described T. helleri from Madagascar, Nosy Faly Island. The description and figure are very detailed, thus allowing a comparison with T. foresti. They agree in most characters, in particular the shape of the front and the male abdomen. It is highly probably that T. helleri is a senior synonym of T. foresti. A final decision is precluded because the type material of the former is not available and therefore cannot be examined with regard to Go/1 morphology and other diagnotic characters.
New genus Thranita from Evans (2018, PeerJ);

References : PDF list, 214 pp (1.4 Mo)

This species in Worms Database