Alpheus rudolphi Almeida & Anker, 2011

Anker, Arthur, Tavares, Marcos & Mendonça, Joel B., 2016, Alpheid shrimps (Decapoda: Caridea) of the Trindade & Martin Vaz Archipelago, off Brazil, with new records, description of a new species of Synalpheus and remarks on zoogeographical patterns in the oceanic islands of the tropical southern Atlantic, Zootaxa 4138 (1), pp. 1-58 : 27-30

Alpheus rudolphi Almeida & Anker, 2011

( Figs. 9 , 10 )

Alpheus rudolphi Almeida & Anker 2011: 3 , figs. 1–22; Hurt et al. 2013: 4533, fig. 1F; Soledade & Almeida 2013: 105; Cunha et al. 2015: 49.

Alpheus armatus — Coelho et al. 1983: 136 (table), 140; Coelho et al. 2006: 51 [not A. armatus Rathbun, 1901 ].

Material examined. Brazil: 1 male, MZUSP 33252, Trindade Island, Enseada dos Portugueses, Ponta da Calheta, 20°30’18.7”S – 29°18’31.6”W, depth: 15.9 m, coll. J.B. Mendonça, 12.v.2014; 1 female, MZUSP 33255, same collection data; 1 ovig. female, MZUSP 33253, Trindade Island, Enseada dos Portugueses, Ponta da Calheta, 20°30’18.7”S – 29°18’31.6”W, depth: 16 m, coll. J.B. Mendonça, 16.v.2014; 1 male, OUMNH.ZC 2016.02.0 19, same collection data; 1 female, MZUSP 33265, Trindade Island, Enseada dos Portugueses, Ponta da Calheta, 20°30’18.7”S – 29°18’31.6”W, depth: 15.6 m, coll. J.B. Mendonça, 30.iv.2014; 1 male, 1 ovig. female, MZUSP 33342, Trindade Island, Enseada dos Portugueses, Ponta da Calheta, 20°30’18.7”S – 29°18’31.6”W, depth: 15.2 m, coll. J.B. Mendonça, 14.v.2014. Size of largest male: cl 11.5 mm ( MZUSP 33342); largest female: cl 13.0 mm ( MZUSP 33253).

Description. See Almeida & Anker (2011) for original description and illustrations.

Distribution. Southwestern Atlantic: endemic to Brazil: Ceará, Alagoas, Bahia, Espírito Santo, Trindade Island ( Almeida & Anker 2011; Hurt et al. 2013; present study).

Ecology. Rocky reefs with corals and sponges; associated with crevice-dwelling aiptasiid sea anemones, presumably Bellactis ilkaluseae Dube (see below); from shallow subtidal to about 50 m.

Remarks. Alpheus rudolphi , the most recently described member of the A. armatus Rathbun, 1901 species complex, appears to be endemic to Brazil ( Almeida & Anker 2011; Soledade & Almeida 2013; Hurt et al. 2013). The species was originally described based on a single specimen dredged off Alagoas and later recorded from Ceará ( Hurt et al. 2013, this record requires confirmation), Espírito Santo (based on underwater photographs from Guarapari, see below), and Pernambuco ( Cunha et al. 2015). The material from Trindade Island represents the first relatively large series of specimens of A. rudolphi , suggesting that the species is relatively common in the area studied.

The colour photographs of the fresh material of Alpheus rudolphi from Trindade Island show for the first time all details of the colour pattern of this striking snapping shrimp ( Figs. 9 , 10 ). The most distinctive features of the colour pattern of A. rudolphi are the presence of a broad white patch running along the mesial surface of the major chela palm (clearly recognisable in the snapping shrimp from Guarapari in Hurt et al. 2013) and a conspicuous white line extending from the flanks of the carapace to the sixth pleonite ( Figs. 9 , 10 ). The absence of yellow-green spots on the dorsal surface of the body and antennular peduncles is shared only with A. immaculatus Knowlton & Keller, 1983 ; these spots are present in other three species of the A. armatus complex ( Knowlton & Keller 1985).

The aforementioned details of the colour pattern of Alpheus rudolphi enable us to confirm the identity of a snapping shrimp in an underwater photograph published in Hurt et al. (2013). The photographed snapping shrimp was found in association with an aiptasiid sea anemone, presumably Bellactis ilkaluseae Dube , and was assumed to represent A. rudolphi based on the general similarity of the colour patterns in the members of the A. armatus complex (cf. Knowlton & Keller 1985; Hurt et al. 2013: fig. 1A–D) and the fact that all other members of this complex are also associated with sea anemones. Remarkably, not a single specimen from Trindade Island was collected together with a sea anemone (J.B. Mendonça, pers. obs.). However, aiptasiid sea anemones typically live deep in rock crevices and retract their tentacles very quickly upon the slightest disturbance; therefore, it is possible that they may have been simply overlooked by the collector. The association between A. rudolphi and sea anemones (possibly B. ilkaluseae ) is corroborated by three underwater photographs taken at Ilhas Rasas and Guarapari, Espírito Santo, and Abrolhos, Bahia ( Fig. 10 C–E).

The uniqueness of the colour pattern of A. rudolphi and the possible symbiotic association with a sea anemone of the genus Bellactis (as opposed to Bartholomea and Ragactis ), corroborate several morphological differences between A. rudolphi and its four relatives ( Almeida & Anker 2011), as well as the sister group position of the Brazilian taxon to the Caribbean Sea—Florida clade regrouping the four remaining taxa, based on molecular data ( Hurt et al. 2013).

Figures

FIGURE 9. Alpheus rudolphi Almeida & Anker, 2011, male from Enseada dos Portugueses, Trindade Island, Brazil (OUMNH. ZC 2016.02.019): A — dorsal view; B — lateral view. Photographs by J. B. Mendonça.

FIGURE 10. Alpheus rudolphi Almeida & Anker, 2011: A, B — female from Enseada dos Portugueses, Trindade Island, Brazil (MZUSP 33255), A — dorsal view; B — lateral view; C – E — in situ photographs of A. rudolphi associated with sea anemones at three localities in Brazil: C — Ilhas Rasas, Espírito Santo; D — Guarapari, Espírito Santo; E — Abrolhos, Bahia. Photographs by J. B. Mendonça (A. B), R. Macieira (C), P. Wirtz (D), M. Lisa (E).