Synalpheus cf. africanus Crosnier & Forest, 1965

Anker, Arthur, Pachelle, Paulo P. G., Grave, Sammy De & Hultgren, Kristin M., 2012, 3598, Zootaxa 3598 (1), pp. 1-96 : 9-11

publication ID	https://doi.org/ 10.11646/zootaxa.3598.1.1
publication LSID	lsid:zoobank.org:pub:74562879-7AB4-42D7-B894-09BFA4885324
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treatment provided by	Felipe
scientific name	Synalpheus cf. africanus Crosnier & Forest, 1965
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Synalpheus cf. africanus Crosnier & Forest, 1965 View in CoL View at ENA

( Figs 3 View FIGURE 3 , 4 View FIGURE 4 )

Material examined. São Tomé: 1 male, OUMNH. ZC.2012-07-090, 200 m west of Lagoa Azul , rocky shore with coralline algae, rock crevices, low tide, coll. A. Anker, N. Knowlton, 31.01.2006 [fcn 06-063B]; 1 ov. female, OUMNH. ZC.2012-07-130, Praia Lagarto, near Hospital, sand with Montastrea sp. , zoanthids and rocks embedded in sand, low tide, coll. A. Anker, N. Knowlton, 30.01.2006 [fcn 06-029*]. Panama: 1 ov. female, OUMNH. ZC.2012- 07-119, Bocas del Toro , Isla Colón, Boca del Drago , coral rocks, 0.5–1 m, coll. A. Anker, 20.10.2005 [fcn 05- 060B*]. Dominican Republic: 1 male, 1 ov. female, OUMNH. ZC.2012-07-117, Bayahibe, coral rocks, 1–2 m, coll. A. Anker, 02- 03.01.2005 [fcn 05-037]. Aruba: 1 female, RMNH D54829, Pos Chiquito, coral rocks, 0.5–1 m, coll. A. Anker, 07- 08.12.2003 [fcn 03-005]. Brazil: 1 male (dissected), 1 ov. female , 1 juvenile, MNRJ 23326 View Materials , Atol das Rocas, Piscina Mapas, coll. unknown, 01.01.2001 ; 3 males, 2 ov. females, MNRJ 23327 View Materials , Atol das Rocas, E of Laguna Interna , calcareous algae, ~ 1 m, coll. F.B. Pitombo, R. Barroso, 18.10.2000 ; 3 males, MNRJ 23328 View Materials , Atol das Rocas, Piscina do Cemitério , calcareous algae, coll. unknown, 01.01.2001 ; 3 ov. females, MNRJ 23329 View Materials , Atol das Rocas, Piscina das Rocas , sta. R8 , calcareous algae, coll. P.S. Young, P.C. Paiva, A.A. Aguiar, 07.10.2000 ; 6 males, 3 ov. females, OUMNH. ZC.2012-07-114, Atol das Rocas, Piscina das Rocas, sta. R8 , calcareous algae, coll. P.S. Young, P.C. Paiva, A.A. Aguiar, 07.10.2000 .

Size range. São Tomé: male, 4.0 mm cl, female, 4.3 mm cl; Caribbean: males, 4.5–4.6 mm cl; 3.9–5.0 mm cl; Brazil: males, 3.6–5.2 mm cl; females, 4.8–6.0 mm cl.

Colour in life. (probably two or more taxa, see below); female from São Tomé: transparent bluish with reddish chromatophores; major chela distally darker olive-green; eggs dark green ( Fig. 4a View FIGURE 4 ); female from Panama: semitransparent with some reddish chromatophores on abdomen and carapace; major chela fingers pale bluish with some white areas; eggs dark green ( Fig. 4b View FIGURE 4 ); female from the Dominican Republic: pale yellow-brownish with some reddish chromatophores; chela darker olive-green distally; walking legs with reddish chromatophores (similar to some specimens of S. townsendi ); eggs pale brownish; colour of specimens Aruba and Brazil (Atol das Rocas) not recorded.

Distribution. (probably two or more taxa, see below) Eastern Atlantic: São Tomé. Western Atlantic: Caribbean Sea: Panama [Bocas del Toro], Dominican Republic [Bayahibe], Aruba; Brazil: Atol das Rocas (present study; see map in Fig. 51 View FIGURE 51 ).

Ecology. Shallow subtidal reef habitats; depth range: 0.5–2 m; in crevices of dead eroded corals or coralline algae (present study); apparently in heterosexual pairs.

Remarks. The eastern and western Atlantic material here assigned to S. cf. africanus likely contains more than one species. In the male specimen from São Tomé (OUMNH.ZC.2012-07-090), the major chela bears a prominent, distally blunt tubercle, which is much stronger than in the other specimens from São Tomé identified as S. africanus or in the specimen of S. africanus illustrated by Crosnier & Forest (1966: fig. 29c). In the ovigerous female from São Tomé (OUMNH.ZC.2012-07-130), the rostrum is very short and somewhat broadened at the base, approaching the configuration of S. congoensis ( Crosnier & Forest 1966: fig. 31a, f; see below); however, it is not really dorsally flattened as in S. congoensis . In the proportions of the merus and carpus of the third and second pereiopods, respectively, this individual appears to be closer to S. africanus than to S. congoensis . Preliminary DNA sequencing of both São Toméan specimens of S. cf. africanus showed that they are genetically distinct from each other and from a typical specimen of S. africanus . It is presently unknown if they are genetically related to any of the western Atlantic specimens of S. cf. africanus (see below).

The western Atlantic material of S. cf. africanus was collected at four different localities: Panama, Aruba, Dominican Republic and Brazil (Atol das Rocas). This material was initially identified as S. cf. tenuispina Coutière, 1909 , using the key in Ríos & Duffy (2007). Synalpheus tenuispina is a poorly known species originally described as S. latastei tenuispina Coutière, 1909 based on a single female from Desterro, Brazil ( Coutière 1909). Subsequently, Holthuis (1952a) placed S. latastei Coutière, 1909 in the synonymy of S. spinifrons (H. Milne Edwards, 1837) , an eastern Pacific species from southern Peru and Chile, but did not comment on the taxonomic status of Coutière’s subspecies tenuispina , except for a brief note on its occurrence in the western Atlantic. Crosnier & Forest (1965, 1966), under the description of S. africanus (as S. hululensis africanus ), suggested elevating S. latastei tenuispina to full species rank, listing it as S. tenuispina several times in the text (Crosnier & directly dealing with S. tenuispina, Ríos & Duffy (2007) , listed it as a distict species in the key (idem., p. 78). Crosnier & Forest (1966) noticed a great morphological similarity between S. tenuispina and S. africanus . The main differences between these two species lie in the length of the distolateral tooth of the scaphocerite, which distinctly overreaches the end of the carpocerite in S. tenuispina vs. falling short of it in S. africanus , and in the shape of the rostrum, very slender, spiniform in S. tenuispina vs. wider, stouter in S. africanus ( Coutière 1909: fig. 8a; Crosnier & Forest 1966: fig. 29a). Therefore, the western Atlantic specimens initially identified as S. cf. tenuispina were re-examined and compared to S. africanus . The specimens from Atol das Rocas ( Fig. 3 View FIGURE 3 ), Aruba and Panama are indeed closer to S. africanus than to S. tenuispina in the length of the scaphocerite and shape of the rostrum. In the two specimens from the Dominican Republic, the length of the scaphocerite is more similar to that of S. tenuispina , whilst the rostrum approaches the typical configuration found in S. africanus . Importantly, all the Caribbean and Atol das Rocas specimens are adults (including several ovigerous females), yet they are significantly smaller than the presumably lost type of S. tenuispina , a very large female with 30 mm tl ( Coutière 1909; Crosnier & Forest 1965). Further, the female from Panama differs from the female from the Dominican Republic in the proportions of the scaphocerite relative to the carpocerite (see above), and also has a different colour pattern, suggesting that the western Atlantic material of S. cf. africanus includes more than one taxon.

With rather limited material of S. cf. africanus and the poor taxonomic knowledge of S. tenuispina it is extremely difficult to determine the true identity of these specimens. A more detailed study of this species complex, including collection of fresh material at the type locality of S. tenuispina in Bahia, a careful morphological analysis, and sequencing of the barcoding gene (COI) in S. tenuispina , eastern and western Atlantic specimens of S. cf. africanus , and S. africanus from throughout its range (Mediterranean Sea, Canary Islands, West Africa), will be necessary to shed more light on the taxonomic identity of S. cf. africanus .