Pinnotherotonia, Marin, Ivan & Paulay, Gustav, 2010

Marin, Ivan & Paulay, Gustav, 2010, Pinnotherotonia rumphiusi gen. et sp. nov., a new furry bivalve-associated pontoniine shrimp (Crustacea: Decapoda: Palaemonidae) from Palau, Zootaxa 2636, pp. 37-48 : 37-38

Pinnotherotonia gen. nov.

Diagnosis. Medium-sized pontoniine shrimp with swollen, slightly depressed body; body and appendages densely covered with small, simple setae. Carapace swollen, without teeth; rostrum well developed, broad, reaching to distal margin of antennular peduncle, curved downward, dorsally and ventrally unarmed, ventral carina forming distinct keel between antennular segments, with slightly developed lateral carina. Abdominal somites unarmed, with tergites non-carinate; three last pleomeres small, with feebly developed rounded pleurae. Telson stout, strongly tapering, with two pairs of small, stout, dorsal spines, with posterior margin blunt, without distal spines, with a row of long, submarginal setae. Eyes large, swollen, thick, dorsally covered with simple setae; cornea slightly reduced, rounded, pigmented; eyestalk swollen, cylindrical. Antennule and antenna normal but significantly reduced, mostly covered by eyes and carapace; basal peduncular segment of antennule without ventromesial and distolateral teeth; scaphocerite of antenna reduced, ear-shaped, without distolateral tooth. Mandible well developed, without palp; maxillula with bilobed palp; maxilla normal, with tapering, simple palp; endites stout; basal endite simple, distally bluntly rounded, furnished with stiff, elongated setae; coxal endite well-developed, distally bluntly rounded, furnished with long simple setae; scaphognathite broad, furnished with short plumose setae; first maxilliped normal; epipod triangular, with medial notch; exopod slender, with expanded caridean lobe; basal and coxal endites completely fused; second maxilliped with normal ear-shaped epipod, exopod long and slender reaching to propodal segment, distolateral margin of propodus broadly rounded, dorsal margin convex, furnished with slender setae, dactylus about 3 times as long as broad; third maxilliped normal. Appendages robust, unarmed; first pereiopod normal; second pereiopod small, robust, equal in size and shape, with unarmed articles, with normal chela; third pereiopod robust, with biunguiculate dactylus; main unguis long and slender, with oblique tip bearing several small teeth; accessory unguis small, triangular. Uropod stout, exopod with bluntly-rounded distolateral angle, with stout curved distolateral spine.

Type species. Pinnotherotonia rumphiusi sp. nov., by present designation and monotypy.

Etymology. The genus is named to reflect its morphological similarity to the bivalve-associated crab genus Pinnotheres Bosque, 1802 ( Decapoda : Brachyura, Pinnotheridae ). Gender feminine.

Systematic position. The new genus can be clearly distinguished from all known pontoniine genera by the very broad rostrum reaching the distal segment of and almost completely covering the antennule; the absence of distolateral tooth on the scaphocerite of the antenna and the absence of distal spines on the telson. The new genus is most similar to the bivalve-associated genera Conchodytes Peter, 1852 and Bruceonia Fransen, 2002 . Conchodytes can be clearly distinguished by its smooth body and appendages, relatively slender, distally compressed rostrum, the presence of large distolateral tooth on scaphocerite of antenna and distal spines on the distal margin of the telson. The monotypic Bruceonia ( B. ardea ) differs from Pinnotherotonia rumphiusi by feebly developed tapering rostrum, well-marked and produced inferior orbital angle of the carapace, the presence of well-developed ventromesial tooth on basicerite of antennula, welldeveloped distolateral tooth of scaphocerite, and well-developed distal spines on the telson. Such densely setose body and appendages are also rarely found within the Pontoniinae ; the only known exceptions being the bivalve-associated Pontonia pilosa Fransen, 2002 and Bruceonia ardeae ( Bruce, 1981) , echinoidassociated Sandimenes hirsutus ( Bruce, 1996) , and coral-associated Ischnopontonia lophos (Barnard, 1962) and Anapontonia denticauda Bruce, 1966 .