Loxopagurus loxochelis ( Moreira, 1901 )

Nucci, Paulo Ricardo & Melo, Gustavo Augusto Schmidt De, 2015, Hermit crabs from Brazil: Family Diogenidae (Crustacea: Decapoda: Paguroidea), except Paguristes, Zootaxa 3947 (3), pp. 327-346 : 338-339

Loxopagurus loxochelis ( Moreira, 1901)

( Figs 4 A, 7A)

Pagurus loxochelis Moreira, 1901: 24 , pl.2, fig. 1a–f.

Loxopagurus loxochelis .— Forest, 1964: 281, figs 1–10.— Forest & Saint Laurent, 1968: 112, figs 66, 67.— Coelho & Ramos, 1972: 170.—Scelzo, 1973: 169; 1976: 44.— Scelzo & Boschi, 1973: 208.— Boschi, 1979: 138.— Coelho & Ramos-Porto, 1986: 52.— Hebling & Rieger, 1986: 72, fig. 6.— Rieger, 1998: 423.—McLaughlin et al., 2010: 22. Loxopagurus loxocheles .—[sic] Melo, 1999: 68, fig. 24 [error].

Material examined. Brazil: Rio de Janeiro—Proj. Ilha Grande, st. 258, 1 spec. (MZUSP-4658); st. 170, 1 spec. (MZUSP-4648); st. 273, 1 spec. (MZUSP-4660); st. 207, 1 spec. (MZUSP-4661); st. 210, 1 spec. (MZUSP- 4650); st. “J”, 16 spec. (MZUSP-4645); st. 99, 1 spec. (MZUSP-4651); st. 101, 3 spec. (MZUSP-4666); st. 12, 3 spec. (MZUSP-4652); st. 58, 1 spec. (MZUSP-4657); st. 236, 3 spec. (MZUSP-4646); st. 304, 1 spec. (MZUSP- 9456); Cabo de São Tomé, 1 spec. (MZUSP-4659); São Paulo—Proj. Monitoramento, 3 spec. (MZUSP-13349); Proj. Integrado, st. 21, 12 spec. (MZUSP-8732); 1 spec. (MZUSP-8760); st. 12, 2 spec. (MZUSP-8761); st. 36, 1 spec. (MZUSP-8764); 1 spec. (MZUSP-8765); st. fixa 2, 1 spec. (MZUSP-8758); st. 48, 1 spec. (MZUSP-8767); st. 6, 4 spec. (MZUSP-8759); st. 22, 1 spec. (MZUSP-8762); st. 42, 2 spec. (MZUSP-8766); st. 24, 1 spec. (MZUSP-8763); Santos, 2 spec. (MZUSP-13141); 1 spec. (MZUSP-4647); Praia Grande, 7 spec. (MZUSP- 13319); 4 spec. (MZUSP-13312); Cananéia, 4 spec. (MZUSP-4669); 1 spec. (MZUSP-6217); Santa Catarina— Imbituba, 3 spec. (MZUSP-9397); st. 14, 6 spec. (MZUSP-8645); st. 1, 4 spec. (MZUSP-8644); 3 spec. (MZUSP-8643); 2 spec. (MZUSP-9392); Itapocoróia, 11 spec. (MZUSP-4663); Rio Grande do Sul—5 spec. (MZUSP-13722); Proj. GEDIP, st. 558, 1 spec. (MZUSP-4681); st. 415, 6 spec. (MZUSP-4677); 1 spec. (MZUSP-4653); 2 spec. (MZUSP-4655); 15 spec. (MZUSP-4676); 1 spec. (MZUSP-4683); 40 spec. (MZUSP- 4688); 2 spec. (MZUSP-4670); 2 spec. (MZUSP-4672); 10 spec. (MZUSP-4682); 20 spec. (MZUSP-4675); 1 spec. (MZUSP-4654); 1 spec. (MZUSP-4684); st. 407, 2 spec. (MZUSP-4674); st. 577, 1 spec. (MZUSP-4673); st. 283, 5 spec. (MZUSP-4687); st. 1643, 6 spec. (MZUSP-4668); 3 spec. (MZUSP-4680); st. 572, 11 spec. (MZUSP-4678); 1 spec. (MZUSP-4649); st. 417, 2 spec. (MZUSP-4667); st. 1645, 1 spec. (MZUSP-4665); st. 557, 1 spec. (MZUSP-4656); st. 1700, 1 spec. (MZUSP-4664); st. 1699, 1 spec. (MZUSP-4671); 3 spec. (MZUSP-4685); st. 397, 1 spec. (MZUSP-4643); st. 1660, 2 spec. (MZUSP-4679); st. 430, 1 spec. (MZUSP- 4662); st. 1687, 2 spec. (MZUSP-4686).

Diagnosis. Shield as long as broad. Antennular peduncle overreaching cornea by half length of last segment. Left cheliped much stronger than right. Dactyls slightly curved. Width of propodus in the median region half length of ventral margin. Dorsolateral and mesial faces of carpus covered by corneous tubercles and separated by row of tooth shaped tubercles. Merus with mesial and lateral faces separated at proximal third by salient ridge armed with corneous spinules. First ambulatory legs reaching end of left cheliped, with strong mesial inwards. Dactyl with row of corneous tubercles on dorsal face; in the lateral and mesial faces, 3 longitudinal striae separated by rows of corneous granules.

Distribution. Western Atlantic—Brazil (from Bahia to Rio Grande do Sul), Uruguay and Argentina.

Remarks. Forest (1964) described the genus Loxopagurus based on Pagurus loxochelis ( Moreira, 1901) , highlighting the many similarities between his new genus and Isocheles , mainly in relation to the aspect of the anterior region of the body, especially the forms of the shield, antennal peduncles and scales, some mouth parts, etc. Forest & Saint Laurent (1968) mention again the strong resemblance between Isocheles and Loxopagurus , except for the remarkable heterochely presented by Loxopagurus . However, in this same work, the authors mention that a species of Isocheles from Guatemala (not described) also features pronounced heterochely, weakening this character as the principal in separating the two genera. In addition, studies on the post embryonic development from both species showed extreme similarity between the larval stages, as it had already been mentioned by Hebling (1978). In his unpublished doctoral thesis, Nucci (2002) suggested that due to these important similarities, the two genera may be synonymous. Unfortunately, Mantelatto et al. (2006) misunderstood what was suggested by Nucci (2002) and published the article cited above with mistaken information based on unpublished data. In this article the authors mention that Nucci (2002) proposed to synonymize Isocheles sawayai and Loxopagurus loxochelis . What was suggested by Nucci (2002), however, was that the two genera could be synonymous, but not the species. Therefore, a more comprehensive study of the two genera is still necessary, which involves the description of all the species not yet described of the genus Isocheles and the use of two or more molecular markers, in order to obtain the best phylogenetic estimate of Loxopagurus in relation to Isocheles . Probably, this is the only way we will be able to confirm or refute the hypothesis of synonymy of the two genera.

Figures

FIGURE 4. Shield and cephalic region: A, Loxopagurus loxochelis; B, Petrochirus diogenes; C, Pseudopaguristes calliopsis.