Talorchestia
Creators: name: Serejo, Cristiana S.
Publisher: name: Zenodo
Year: 2004
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Talitridae
Talorchestia

description: “ Talorchestia ” tucurauna (Müller, 1864) (Figs 11–13)
Orchestia tucurauna Müller, 1864: 54; 1869: 79, figs 50–51 [also printed as O. tucuratinga]; Stebbing, 1906: 534; Chilton, 1919: 379, figs 1–14 (= Talorchestia dentata (Filhol, 1885) non Muller, 1864).
Talorchestia fritzi — Schellenberg, 1938: 211 (non T. fritzi of Stebbing, 1903).
Material examined. Rio Grande do Norte — Rocas Atoll, Farol Island, RN, 87 males, 100 females, S. Brandão et al. col., 10/VII/2001, MNRJ 18739; Golfinhos Bay, Pipa, RN, 7 males, 3 females, C. Serejo & M.C. Rayol col, 11/11/2001, MNRJ 18741; Between Barreira d'agua beach and Roxa beach, Natal, RN, 1 male and 1 female, 27/I/1964, MNRJ 18740. Pernambuco — Jaguaribe, Itamaracá Island, PE, 13 males and 40 females, 12/IX/ 1976, MNRJ 9770. Alagoas — Graça Torta beach, Maceió, AL, 1 male, 2 females, 06/III/ 1980, MNRJ 4646. Bahia — Yemanjá beach, Caravelas, BA, 25 males, 60 females, P.S. Young col., 21/IX/2001, MNRJ 18742; Rio do Peixe beach, Cumuruxatiba, Prado, BA, 18 males, 70 females, P.S. Young, col. 16/IV/2003, MNRJ 18746. Rio de Janeiro — São João da Barra, RJ, 4 males, A. Lemos de Castro col. 31/X/1973, MNRJ 9766; Barra do Una, Búzios, RJ, V. Veloso col. 2/IV/2003, MNRJ 19141.
“ Talorchestia ” tucurauna (Müller, 1864), male, 9.2 mm, MNRJ 18739. A, head; B, gnathopod 1; C, ventral view of coxa 1; D, gnathopod 2; E, pereopod 3; F, pereopod 4. Scale bars: A, 1 mm; B–E, 0.5 mm; F, 0.2 mm.
Diagnosis. Male antenna 2 with articles 4–5 long and slender, article 5 slightly longer than article 4. Male gnathopod 2, propodus about 1/4 longer than wide, palm with a large proximal concavity that fits in a projection of the dactylus. Female gnathopod 2, basis enlarged anteriorly, propodus posteriorly rounded. Outer ramus of uropod 1 with marginal robust setae. Telson slightly cleft.
Description. Male, 9.2 mm. Antenna 1 reaching half way of article 4 of peduncle of antenna 2, flagellum with 5 articles. Antenna 2, peduncle long and slender, article 5 slightly longer than article 4, article 4 about 4 times longer than wide, article 5 about 5 times longer than wide; flagellum with 24 articles (Fig. 11A). Mandible with left lacinia mobilis 5­dentate; right lacinia mobilis bifid. Maxilla 1, inner plate with two distal plumose setae; outer plate with 9 dentate robust setae, palp reduced and 1­articulate. Maxilla 2, inner plate with several distal setae and a larger proximal plumose seta; outer plate a little larger than inner plate. Maxilliped palp robust, 3­articulate, article 2 with well developed inner setose distal lobe.
Gnathopod 1 subchelate (Fig. 11B), coxa 1 with a ventral groove, inner margin tipped with slender setae (Fig. 11C), carpus and propodus with well developed posterior lobe. Gnathopod 2 robust and sexually dimorphic (Fig. 11D), palm with a large proximal concavity that fits in a projection of the dactylus. Pereopod 4 a little shorter than pereopod 3, dactylus enlarged (Fig. 11E, F). Dactylus of pereopods 3–7 cuspidactylate. Pereopods 5–7 increasing in length (Fig. 12 A–C). Posterior lobe of coxa 6 rounded, about 1.7 the length of anterior lobe. Pleopods not modified. Uropods 1–2 with robust setae on peduncles and rami (Fig. 12 D, E). Peduncle of uropod 3 a little longer than ramus (Fig. 12 F). Telson longer than wide, slightly cleft distally, each side with 8–9 sub­marginal and marginal robust setae (Fig. 12 G).
Female, 9.5 mm Antenna 2 (Fig. 13 A), peduncle articles 4–5 not so long as in males, article 4 about 3 times longer than wide and article 5 about 4 times longer than wide. Gnathopod 1 simple (Fig. 13 B). Gnathopod 2 (Fig. 13 C), basis enlarged anteriorly, propodus posteriorly rounded. Oostegites 2–5 oval shaped and slightly tapering distally, oostegite 5 a little shorter than the others (Fig. 13 D–G).
Type locality. Brazil, probably Santa Catarina.
Distribution. Brazil: from Rio Grande do Norte to?Santa Catarina, including Rocas Atoll (03º 52' S; 033º 48' W), an oceanic Island distant about 70 km off the Rio Grande do Norte coast.
Ecology. Often inhabiting exposed sand­beaches, found together with Atlantorchestoidea brasiliesis at Rio de Janeiro. This is the single species that colonized the Rocas Atoll.
Remarks. Müller (1864) briefly described and illustrated T. tucurauna, which makes its identification a little uncertain. As mentioned before, Mullers types are probably lost and material from the possible type locality, Santa Catarina, have not been found. For these reasons, the necessity of describing a neotype is still needed.
Compared with the observed material, the gnathopod 2 propodus illustrated by Müller (1869) is slightly more rounded (Figs. 11D and 13I). Furthermore, Müller (1869) described a sexual dimorphism in old males (fusion of 1 to 4 first articles in the flagellum of antenna 2 and the enlargement of intermediary articles of pereopod 7), which was not observed in the present material.
Talorchestes tucurauna resembles T. fritzi Stebbing (1903), which was described originally for the Pacific coast of Costa Rica. Stebbing (1903) commented on the similarities of these species as the palm of gnathopod 2 bearing a proximal excavation, and a corresponding prominence of the dactylus that fits in this excavation. Stebbing (1903) also noticed some distinctions between T. fritzi and T. tucurauna, as the propodus of male gnathopod 2 is 2/5 longer than wide, and not 1/4 to 1/5 longer than wide; the female gnathopod 2, basis has a sinuous anterior margin, not anteriorly rounded; carpus and propodus are distinctly narrower than in T. tucurauna, and the propodus has a sinuous posterior margin, not rounded.
Shoemaker (1932), who worked with Costa Rica samples, also noticed the similarities between T. fritzi and T. tucurauna, but as the description of the latter did not have the condition of female gnathopod 1, he just suggested a possible synonymy between these taxa. Schellenberg (1938), who worked with material from the northeastern Brazilian coast, identified it as T. fritzi. However, Schellenberg's specimens are clearly T. tucurauna by the shape of propodus of male gnathopod 2 (1/4 longer than wide) and by the carpus and propodus of female gnathopod 2 not elongated as in T. fritzi. Furthermore, Schellenberg (1938) described the characteristic development of male gnathopod 2 in this species.
Genus status. The concept of Talorchestia as applied by Stebbing (1906a), "like Orchestia, except that female gnathopod 1 is simple, instead of subchelate. Pereopod 2 [actually pereopod 4] usually has the inner margin of the finger more sharply constricted than in allied genera" is brief and difficult to apply in a modern concept when compared to other genera (Hurley, 1956). Considering these points, Morino & Miyamoto (1988) and later on Miyamoto & Morino (1999) redefined Talorchestia, including the type species T. gracilis Dana, 1852, and other three species of the tropical Pacific spinipalma ­complex. “ Talorchestia ” tucurauna differs from this new definition of Talorchestia by palm of male gnathopod 1 being longer than dactylus, female gnathopod 2 without constriction on the distal end of carpus, and uropod 1 outer ramus has robust setae. Thus, T. tucurauna is part of the Talorchestia s.l complex, which has not been fully revised yet. Bellan­Santini & Ruffo (1991) had the same problem with the new species “ Talorchestia ” ungolinii described from the Mediterranean Sea. Later on, Tafani et al. (2004) proposed a revision based on mitochondrial DNA on the Mediterranean Talorchestia s.l species. Based on this analysis, a preliminary diagnosis of two new genera were proposed by Ruffo in Tafani et al. (2004), but none of these would comprise the Brazilian species. A currently study with Australian coastal talitrids with a further revision within the Talorchestia s.l complex is being prepared (Serejo in prep.).
description: Published as part of Serejo, Cristiana S., 2004, Talitridae (Amphipoda, Gammaridea) from the Brazilian coastline, pp. 1-29 in Zootaxa 646 on pages 21-26, DOI: 10.5281/zenodo.158648