Siderochinia, Yan & Lee & Forges & Ng, 2021

Yan, Bee, Lee, Forges, Bertrand Richer De & Ng, Peter K. L., 2021, The generic affinities of the Indo-West Pacific species assigned to Rochinia A. Milne-Edwards, 1875 (Crustacea: Brachyura: Majoidea: Epialtidae), Raffles Bulletin of Zoology 69, pp. 19-44 : 33-34

publication ID	https://doi.org/ 10.26107/RBZ-2021-0004
publication LSID	lsid:zoobank.org:pub:80B28514-EBB5-4506-AAB1-637DF477E5A0
persistent identifier	https://treatment.plazi.org/id/795B1368-EA72-FFEE-E9DE-C3630B01F782
treatment provided by	Diego
scientific name	Siderochinia
status	gen. nov.

Treatment

Siderochinia View in CoL , new genus

Type species. Pugettia kagoshimensis Rathbun, 1932 View in CoL , by present designation.

Species composition. With two species ( Table 1).

Diagnosis. Carapace pyriform, covered with layer of short setae which obscures carapace surface. Pseudorostral spines long, slender, diverging at approximately 45° angle. Supraorbital eave with preorbital angle distinct; postorbital angle lobe cup-like, round anterior margin. Carapace with strong hepatic, cardiac, lateral branchial, posterior spines ( Fig. 7A, D View Fig ). Antennal flagellum shorter than pseudorostral spines. Basal antennal article longer than broad, distal angle blunt, relatively straight outer margin. Distal angle of buccal frame blunt, not raised. Pterygostomial region with granules on outer margin ( Fig. 7B, E View Fig ). Male chelipeds short, propodus slightly inflated, rounded margins; carpus with rounded margin; merus with distinct, blunt distal angle, with margin rounded. Ambulatory legs slender, articles with rounded margins; merus with blunt distal angle; short spines present on ventral margin of P2–P5 dactyli, strongest on P4, P5 ( Figs. 7A, D View Fig , 8C, F View Fig ). Male thoracic sternum anteriorly slightly depressed; sternites 3, 4 narrow, lateral margins slightly constricted. Male pleon triangular, telson triangular; somites with slightly raised granules medially ( Fig. 7B, E View Fig ). G1 straight with wide, flattened tip ( Fig. 9G, H, K, L View Fig ); G2 slight curved, distal outer margin concave, distal rip rounded ( Fig. 9I, J View Fig ).

Etymology. The species in the genus possess strong hepatic, cardiac, lateral branchial and posterior spines, which makes it look like a star. The name is derived from the Latin word “sideris” for star, in arbitrary combination with the genus name Rochinia . Gender feminine.

Remarks. Comparison of the morphological characters showed several differences between Siderochinia , new genus, and allied genera. In Siderochinia , the hepatic spine is large and directed outwards ( Fig. 7A, D View Fig ) (vs. the hepatic spines are short and weak on Samadinia and Crocydocinus ; cf. Lee et al., 2019: figs. 13A–D, 14A–C; Fig. 1A–D View Fig ); there is a strong spine on each of the mesogastric and cardiac regions ( Fig. 7A, D View Fig ) (vs. only granules, tubercles, or weak spines on the same regions on Samadinia ; Fig. 1A–D View Fig ; large carapace granules on each region on Crocydocinus ; cf. Lee et al., 2019: figs. 13A–D, 14A–C); the ambulatory legs are proportionately much shorter and stouter, with the P5 merus length approximately 2.3–3.5 times width in Siderochinia ( Figs. 7A, D View Fig , 8C, F View Fig ) (vs. ambulatory legs generally longer and more slender, with P5 merus length more than 3.5 times width in Samadinia , Crocydocinus , and Laubierinia ; cf. Fig. 1A–D View Fig ; Lee et al., 2019: figs. 13A–D, 14A–C; Fig. 5A, D View Fig ); the P2–P5 meri are not carinate in Siderochinia and Samadinia ( Figs. 1A–D View Fig , 7A, D View Fig , 8C, F View Fig ) (vs. with dorsal margin weakly carinate or not carinate in Laubierinia ; cf. Fig. 5A, D View Fig ; Richer de Forges & Ng, 2009b: figs. 6E, 10A, 11D); the ventral margin P2 and P3 dactyli have weak spines while those of P4 and P5 have distinct short spines in Siderochinia ( Figs. 7A, D View Fig , 8C, F View Fig ) (vs. the ventral margins of P2–P5 dactyli smooth or with only small granules in Samadinia and Crocydocinus , and the P3–P5 dactyli with short spines in Laubierinia ; cf. Fig. 1A–D View Fig ; Lee et al., 2019: figs. 13A–D, 14A–C; Fig. 5A, D View Fig ); and the male thoracic sternites 3 and 4 are narrow, with the lateral margins slightly constricted ( Fig. 7B, E View Fig ) (vs. male thoracic sternites 3 and 4 transversely narrow, constricted anteriorly, lateral margin relatively straight to constricted medially on Samadinia ; Fig. 2A–D View Fig ; sternites 3 and 4 wide, lateral margins slightly constricted on Crocydocinus ; see Lee et al., 2019: figs. 15A–D, 16A–C).

Compared to Tunepugettia , Siderochinia differs in having rounded, cylindrical ambulatory legs without any marginal carinae ( Figs. 7A, D View Fig , 8C, F View Fig ) (vs. having carinate margins on the ambulatory meri and propodi in Tunepugettia ; cf. Lee et al., 2019: figs. 10A, 11A, D); and the G1 has only a single flattened distal tip ( Fig. 9G, H, K, L View Fig ) (vs. G1 having bilobed distal tip in Tunepugettia ; cf. Lee et al., 2019: fig. 12A–D; Ng et al., 2017a: fig. 7). Siderochinia differs from Goniopugettia in lacking an epibranchial spine, and the hepatic and lateral branchial spines on the carapace are directed outwards and in opposite directions ( Fig. 7A, D View Fig ) (vs. having prominent epibranchial spine, and the hepatic and lateral branchial spines on the carapace are directed outwards and parallel to each other in Goniopugettia ; cf. Ng et al., 2017a: figs. 1, 2A); and the pseudorostral spines are not fused, long, slender and cylindrical ( Fig. 7A, D View Fig ) (vs. the pseudorostral spines are fused along proximal half, and are dorsal-ventrally flatted in Goniopugettia ; cf. Ng et al., 2017a: figs. 1, 2A). Siderochinia is different from Oxypleurodon in the absence of carapace plates and the lack of any distinct raised ridge on the posterior region of the carapace ( Fig. 7A, D View Fig ) (vs. having distinct or weak carapace plates and distinct raised ridge on the posterior region of the carapace in Oxypleurodon ; cf. Richer de Forges & Ng, 2009b: figs. 1A, 2A–D, 3A–F, 4A, C, 5A, 7A–E); and having the male thoracic sternum slightly depressed anteriorly with sternites 3 and 4 narrow, with the lateral margins slightly constricted ( Fig. 7B, E View Fig ) (vs. the male thoracic sternum is concave anteriorly with sternites 3 and 4 narrow and the lateral margins constricted medially in Oxypleurodon ; cf. Richer de Forges & Ng, 2009b: fig. 4B, D).