Genus Thylakogaster Wilson & Hessler, 1974

Thylakogaster Wilson & Hessler, 1974: 48; Kussakin, 1988: 355.

Type species. Thylakogaster peterpauli Wilson & Hessler, 1974, by original designation. Species included: Thylakogaster peterpauli Wilson & Hessler, 1974; Thylakogaster majusculus Wilson & Hessler, 1974; Thylakogaster lobotourus Wilson & Hessler, 1974 .

Diagnosis (modified from Wilson & Hessler 1974): Head laterally angular or curved in dorsal view; with transverse ridge and frons­clypeal furrow; depth subequal or greater than pereonite 1. Body with many thin­walled spines or spinules, including cuticle of dorsolateral sides of head, lateral and posterior sides of pleon, and external surfaces of pleopods 1and 2; spines also on coxae, lateral margins of pereonites 1 and 2; dorsum of pleon devoid of such spines. Female developing oostegites on coxae internal to sternal surface. Pleotelson strongly inflated, hollow, expanded dorsally and laterally into somewhat bilobed form, reflected anteriorly, lying above pereonites. Mandible without palp; molar process tapering distally into tuft of thin, curved spines. Maxilliped epipodite triangular, small, width less than basis width, length less than half basis length. Pereopods II and III elongate, distinctly longer than head–pereon length; carpus and propodus curving medially, strongly opposing each other, combined lengths exceeding two­thirds total pereopod length, with large curved setae; dactylus short, covered with fine cuticular hairs, with single claw. Pereopods IV– VII longer than pereopods II and III, more slender and straight, with smaller setae and with long, slender claw and second vestigial claw on dactylus. First pleopod copulatory male posterior margin sagittate. Uropods uniarticulate, positioned ventroposteriorly close to tip of pleon.