On the Eastern Pacific Species of the Paralichthyid Flatfish Genus Citharichthys: Redescription of C. fragilis, Comments on the Taxonomic Status of C. gordae, and a Key to the Species
The brief original description, without illustration, of Citharichthys fragilis was based on specimens collected in the central and northern Gulf of California, Mexico. We expand the description of the species, including its secondary sexual dimorphism, and compare it with C. gordae, a similar, relatively deep-water sanddab, mainly, although rarely, collected from the southern Gulf of California. We reject the recent placement of C. gordae in the synonymy of C. fragilis and conclude that both species are valid. They show an essentially allopatric distribution, C. fragilis being quasi-endemic and C. gordae endemic to Mexico. The distributional range of C. gnathus is widened from the Galapagos Islands to the Pacific coast of Colombia, and the Gulf of California is excluded from the geographical range of C. xanthostigma. A key to the species of Citharichthys from the eastern Pacific is provided. La breve descripción original de Citharichthys fragilis, sin ilustración, se basó en individuos recolectados en la parte central y norte del Golfo de California, México. En el presente estudio se amplía la descripción de esta especie, aportando información sobre su dimorfismo sexual y comparándose con la cercana C. gordae, especie rara de aguas medio profundas, que principalmente se recolecta en el sur del Golfo de California. Rechazamos la reciente puesta en sinonimia de C. gordae con C. fragilis y concluimos que ambas especies son válidas con una distribución casi alopátrica, siendo C. fragilis cuasi-endémica y C. gordae endémica a México. Se amplía el rango de distribución geográfica de C. gnathus desde las Islas Galápagos hasta la costa del Pacífico de Colombia, y se excluye al Golfo de California del rango de la distribución de C. xanthostigma. Se proporciona una clave para las especies de Citharichthys del Pacífico oriental.Abstract
Resumen
(A) Citharichthys fragilis, male, 100.5 mm SL, 122.8 mm TL, CIAD 82-26; (B) C. gordae, female, 112.1 mm SL, 135.5 mm TL, CIAD 92-4; (C) C. gnathus, male, 98.2 mm SL, 118.9 mm TL, UCR 1903.002.
Symphysis of lower jaw with differing types of outgrowths: (A) bump-like, Citharichthys fragilis, female, CIAD 82-26, 118.7 mm SL; (B) knob- to cone-like, C. gordae, (a) male, CIAD 90-15, 104.1 mm SL, (b) female, CIAD 92-4, 110.0 mm SL, (c) female, CIAD 92-4, 119.6 mm SL; (C) hook-like, C. gnathus, UCR 1903.002, (a) female, 101.5 mm SL, (b) male, 89.2 mm SL. Scale = 5 mm.
Variation in sexual dimorphism in morphology of urogenital papillae of Citharichthys fragilis: (A) females, papillae small and conical, (a–c) CIAD 85-18, 92.4, 105.7, and 97.0 mm SL, respectively; (B) males, papillae large, broad and split at distal end, (d–e) CIAD 85-18, 96.1 and 100.7 mm SL, respectively, (f) CIAD 82-12, 89.2 mm SL. Scale bars = 0.5 mm.
Geographical distribution of Citharichthys fragilis (solid circles; holotype solid star), C. gordae (open circles; holotype open star). Presence of C. gnathus off Colombia (triangle). Circles and triangle denote specimens examined; each circle may represent more than one locality or specimen lot. Squares indicate SIO records: solid and open squares correspond to C. fragilis and C. gordae, respectively; half black and half white squares refer to localities where both species were caught together.
Relationship between head length and standard length for Citharichthys fragilis and C. gordae.
Geographic variation in numbers of anal- (solid boxes and dots) and dorsal-fin rays (open boxes and dots) from specimens of C. gordae (Group I) and C. fragilis (Groups II–VI). Groups I and II, southern Gulf of California (23–24°and 24–26°N); III and IV, northern Gulf of California (29–30°and 30–31°N); V, western coast of Baja California peninsula (25–27°N); VI, southern California, USA (33–34°N). Vertical line within box indicates median, left and right box boundaries indicate 25th and 75th percentiles, respectively; error bars indicate 10th and 90th percentiles; dots correspond to minimum and maximum counts and outlying data.
Contributor Notes
Associate Editor: D. Buth.