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Tanaidacea (Crustacea: Peracardia) of the Gulf of Mexico. VIII. Pseudosphyrapus siegi, N. Sp. (Sphyrapidae) from the Continental Slope of the Northern Gulf of Mexico

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Pseudosphyrapus siegi, n. sp. is described from benthic samples collected in deep water (595-2400 m) from the northern Gulf of Mexico. Of the five currently recognized species of Pseudosphyrapus Cup, 1980, P. siegi is most closely related to P. dispar (Lang, 1968), a southwestem Pacific cognate and only other member of the genus having a squama on antenna 2. Pseudosphyrapus siegi is distinguished from P. dispar by: (1) a more triangular, but less acute, rostrum (2) the presence of two 4-pronged spines on the second maxilla (homologous spines on P. dispar are 3-pronged), and (3) the absence of a spiniform process on the chelipedal carpus. Other less noticeable differences between the two species occur in the setation or spination of the maxilliped and pereopods. Except for a small genital cone on males and developing oostegites on females, no noticeable sexual dimorphism (e.g., setation of antenna 1, enlargement or modification of chela and pereopod 1 in males) was exhibited by the specimens of P. siegi examined. It is probable, however, that more fully developed and sexually dimorphic males exist for P. siegi. The limited collection data suggests that body size in P. siegi may increase with depth. A key to the species of the genus Pseudosphyrapus is included.

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