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From January 2008 to December 2009, 451 specimens of witch guitarfish Zapteryx xyster were caught in the Gulf of Tehuantepec. Total weight, total length (TL), sex, maturity stage and catch depth were recorded for each specimen. Maturity stage distribution exhibited significant differences with respect to depth. The data indicated that adults migrated towards shallow waters (25–37m) to reproduce, starting in February. Males reached maturity at 44cmTL, whereas females reached maturity at 48cmTL. Witch guitarfish females are synchronous; therefore, ovulation and mating begin in March and parturition begins in April. Females showed a 2-year cycle with consecutive vitellogenesis and gestation. Fecundity was five to eight embryos (mean six embryos) and the sex ratio of embryos was 1:1. Birth occurred in April and May, with an average size at parturition of 17.3cmTL. There was sexual dichromatism between males and females during the breeding period, and sexual polymorphism in adult females. The incidental catch of the witch guitarfish during courtship and mating threatens the survival of this species.

Psychrolutes phrictus is a benthic deep sea fish known from the eastern North Pacific. On 30 March 2008, a specimen of the blob sculpin P. phrictus (297 mm LT) was caught off the Guerrero coast, Mexico (17 • 45 24 N, 101 • 59 04 W). The blob sculpin was taken at a depth of 1,100 m within a temperature range of 3.88-4.25 • C, where hypoxic (0.57-0.39 mg/l) conditions prevailed; the specimen was captured over a muddy bottom using a benthic sledge. Representatives of this species had never been reported off the Mexican Pacific coast; our new record extends the known southernmost range by 1,733 km, from 33 • 19 N to 17 • 45 N for the American coast. Although high variations in morphometric and meristic values are known for the 4 species of the genus Psychrolutes (P. paradoxus, P. phrictus, P. sigalutes, and P. sio) from the eastern Pacific Ocean, a combination of traits and species distribution allow us to identity this specimen as P. phrictus. All Rights Reserved ResumenPsychrolutes phrictus es un pez bentónico de profundidad, que se distribuye en el Pacífico Norte. El 30 de marzo de 2008 se capturó un espécimen del pez gota P. phrictus (297 mm LT) frente a las costas de Guerrero (17 • 45'24" N, 101 • 59'04" W), a una profundidad de 1,100 m, temperatura de 3.88 a 4.25 • C, donde las condiciones de hipoxia prevalecen (0.57-0.39 mg/l); el arrastre se realizó con un patín béntico sobre un fondo fangoso. A la fecha no se había documentado ningún ejemplar de esta especie en las costas de México, por lo que este nuevo registro extiende el intervalo más sureño de distribución 1,733 km de 33 • 19' N a 17 • 45' N para la costa americana. Aun cuando las variaciones merísticas y morfológicas son grandes en las 4 especies del género Psychrolutes (P. paradoxus, P. phrictus, P. sigalutes y P. sio) en el océano Pacífico oriental, una combinación de caracteres y de su distribución permiten determinar el espécimen en cuestión como P. phrictus. Derechos Reservados © 2016 Universidad Nacional Autónoma de México, Instituto de Biología. Este es un artículo de acceso abierto distribuido bajo los términos de la Licencia Creative Commons CC BY-NC-ND 4.0.

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