Cocorchestia Lowry & Myers 2022, gen. nov.
Creators: name: Lowry, J. K.
name: Myers, A. A.
Publisher: name: Zenodo
Year: 2022
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Malacostraca
Amphipoda
Talitridae
Cocorchestia

description: Cocorchestia gen. nov.
Type species. Talorchestia fritzi Stebbing, 1903.
Included species. Cocorchestia includes 2 species. C. fritzi (Stebbing, 1903) comb. nov. and C. margaritae (Stephensen, 1948) comb. nov.
Category. Mascupod.
Ecological type. Beach hopper.
Habitat. Sandy shores.
Diagnostic description. Based on Stebbing (1903) and Stephensen (1948).
Head. Antenna 2 peduncular articles incrassate. Mouthparts unknown. Maxillipedal palp article 2 probably with distomedial lobe; article 4 probably button-shaped or fused to article 3.
Pereon. Gnathopod 1 subchelate; posterior margin of carpus and propodus each with lobe covered in palmate setae; propodus anterior margin with 3, 6 or 7 groups of robust setae, ‘subtriangular’ with well-developed posterodistal lobe, palm transverse; dactylus simplidactylate. Gnathopod 2 subchelate; propodus palm transverse, sigmoidal, with broad sinus near dactylar hinge, without proximal sinus; with or without proximal spine or thumb defining palm; without large projection near dactylar hinge; dactylus not modified distally, blunt. Pereopod 4 significantly shorter than pereopod 3; carpus significantly shorter than that of pereopod 3; dactylus amplidactylate, thickened proximally with notch midway along posterior margin. Pereopod 6 not incrassate; basis moderately expanded. Pereopod 7 not incrassate; basis expanded; posterior margin with distinct minute serrations, each with a small seta, posterodistal lobe present or posterodistal lobe absent, rounded, produced downwards almost to merus; merus expanded distally, subtriangular, anterior margin slightly convex; carpus unexpanded; subrectangular; carpus slightly shorter than propodus; propodus slender; length 8 × width.
Pleon. Pleopods 1–3 unknown. Uropod 1 peduncle distolateral robust seta absent; exopod without marginal robust setae; endopod with marginal robust setae in 1 row. Uropod 2 exopod with marginal robust setae in 1 row; endopod with marginal robust setae in 1 row. Uropod 3 ramus shorter than peduncle. Telson completely cleft or entire, with 3–6 robust setae per lobe or with 7–9 robust setae per lobe.
Remarks. Cocorchestia appears to be most similar to some species of Platorchestia. It differs from Platorchestia in having a simplidactylate first gnathopod and no proximal sinus on the palm of gnathopod 2. It differs from Insularorchestia mainly in the shape and angle of the palm of gnathopod 2 and the broad sinus near the dactylar hinge.
Distribution. Costa Rica. Isla del Coco, (Stebbing 1903). Coast of Costa Rica (Shoemaker 1932). Turtle Bay, Isla Santa Cruz, (Monod 1970). Venezuela. Porlamar, Isla Margarita, (Stephensen 1948).
description: Published as part of Lowry, J. K. & Myers, A. A., 2022, Platorchestiinae subfam. nov. (Amphipoda, Senticaudata, Talitridae) with the description of three new genera and four new species, pp. 1-53 in Zootaxa 5100 (1) on page 7, DOI: 10.11646/zootaxa.5100.1.1, http://zenodo.org/record/6127681