Adrián F. González-Acosta

An annotated distributional checklist of the freshwater fish from Baja California Sur, México

An annotated distributional checklist of thefreshwater fish recorded historically andrecently in Baja California Sur, México, isprovided. This checklist is supported with4,857 specimens collected at freshwaterlocalities during the period of May 1991 toApril 2002, and complemented with a review ofspecimens in museums and in the literature. Thenative ichthyofauna is represented by 19species belonging to 16 genera and 12 families,with only two cases of endemism (Funduluslima and Gobiesox juniperoserrai). Thefirst occurrence of Centropomus viridisin freshwater environments of Baja Californiapeninsula is reported here. The familiesEleotridae and Mugilidae are the most diversewith 3 species each. Zoogeographically, most ofthe species are of tropical affinity(panamanian 63%, tropical amphiamerican 16%and circumtropical 5%) and of marineecological derivation (sporadic 53%,complementary 26%, vicarious 16% anddiadromous 5%). Six species are exotic in thisregion, of which Cyprinus carpio, Xiphophorus helleri and Tilapia cf. zilli are of recent introduction. The currentstatus of the endemic killifish (Funduluslima) is determined as endangered due tocompetition with Tilapia cf. zilliand other exotic fish.An annotated distributional checklist of thefreshwater fish recorded historically andrecently in Baja California Sur, Mexico, isprovided. This checklist is supported with4,857 specimens collected at freshwaterlocalities during the period of May 1991 toApril 2002, and complemented with a review ofspecimens in museums and in the literature. Thenative ichthyofauna is represented by 19species belonging to 16 genera and 12 families,with only two cases of endemism (Funduluslima and Gobiesox juniperoserrai). Thefirst occurrence of Centropomus viridisin freshwater environments of Baja Californiapeninsula is reported here. The familiesEleotridae and Mugilidae are the most diversewith 3 species each. Zoogeographically, most ofthe species are of tropical affinity(panamanian 63%, tropical amphiamerican 16%and circumtropical 5%) and of marineecological derivation (sporadic 53%,complementary 26%, vicarious 16% anddiadromous 5%). Six species are exotic in thisregion, of which Cyprinus carpio, Xiphophorus helleri and Tilapia cf. zilli are of recent introduction. The currentstatus of the endemic killifish (Funduluslima) is determined as endangered due tocompetition with Tilapia cf. zilliand other exotic fish.

First record of Seriola peruana (Actinopterygii: Carangidae) in the Gulf of California

The fortune jack Seriola peruana is reported in the southern Gulf of California for the first time, further north than its usual area of occurrence in the tropical eastern Pacific. Meristics and morphometric data of the specimen are given.

Osteología Comparada del Esqueleto Caudal de Achirus lineatus y Achirus mazatlanus (Pleuronectiformes: Achiridae)

El esqueleto caudal constituye una importante herramienta para evaluar las relaciones ancestro-descendencia de los peces teleosteos. Por tal motivo, se realizo un analisis osteologico comparativo de dicha estructura, a partir de ejemplares de las especies Achirus lineatus (Linnaeus, 1758) y A. mazatlanus (Steindachner, 1869), obtenidos de colecciones cientificas de referencia y recolectados in situ en Veracruz y Baja California Sur (Mexico). Los organismos fueron identificados con claves taxonomicas especializadas y procesados mediante la tecnica de aclaracion y tincion diferencial, para evaluar las posibles similitudes o diferencias en las estructuras que componen al complejo caudal. Achirus lineatus y A. mazatlanus se caracterizan por la presencia de una formula caudal compuesta por 1 epural + 5 hipurales + 1 parahipural, ademas de una espina neural y dos espinas hemales; asi como por la presencia de 16 radios principales y la ausencia de los radios procurrentes y el uroneural. Asimismo, se observo que en la especie A. lineatus, los hipurales se encuentran mas cercanos uno del otro; sin embargo, en lo general, no se aprecio una clara diferencia en los elementos que componen la aleta caudal de las especies bajo estudio. Por consiguiente A. lineatus y A. mazatlanus son consideradas como especies fraternas.

New species of Eugerres from the Usumacinta Province, México and Guatemala with a redescription of E. mexicanus (Steindachner, 1863) (Teleostei: Gerreidae)

Eugerres castroaguirrei, new species is described from the rio Grijalva-Usumacinta basin of southeastern Mexico and northern Guatemala. Eugerres castroaguirrei and E. mexicanus are distinguishable from their marine estuarine congeners by the dorsal-fin origin posterior to the insertion of the pectoral and pelvic fins, a shorter and broad based supraoccipital crest, and a distinct geographic distribution restricted to freshwater habitats. Eugerres castroaguirrei differs from E. mexicanus by diagnostic characters of the body skeleton: anterior process of supraoccipital convex, infraorbital 1 with foramen, premaxillary ascending process developed with margins curved, pharyngeal plate granular and not serially arranged, and dorsal and anal fin-rays reduced. Likewise, E. castroaguirrei is characterized by an oblong and laterally thicker body (37.6-58.5% HL); greater body depth (33.8-42.1% SL), and eye diameter (23.3-31.6% HL); in addition to 16 significant morphometric characters: length of the second dorsal-fin spine 23.2-34.2% SL; depressed second dorsal-fin spine (extending to base of third to fourth dorsal-fin rays); length of second anal-fin spine 11.1-20.6% SL, depressed second anal-fin spine extending to the base of third to fourth anal-fin rays not reaching the distal point of last anal-fin ray; pelvic-fin spine length 49.7-65.0% in the first pelvic-fin ray length

New records and range extension of three fish species in the Gulf of California

We documented new records and range extension of three fish species for the Gulf of California, one serranid (Diplectrum maximum Hildebrand, 1946) and two labrisomid blennies [Alloclinus holderi (Lauderbach, 1907) and Labrisomus wigginsi Hubbs, 1953]. These records increase to 916 species the known fish fauna in the Gulf of California.

LENGTH-WEIGHT AND LENGTH-LENGTH RELATIONS FOR 14 FISH SPECIES FROM THE CENTRAL MEXICAN PACIFIC COAST

Length-weight (LWR) and standard length-total length (L-L) relations are presented for 14 fi sh species caught in four estuaries from the south-eastern coast of Michoacan, Mexico (Central Pacifi c): Lile nigrofasciata Castro-Aguirre, Ruiz-Campos et Balart, 2002; Pliosteostoma lutipinnis (Jordan et Gilbert, 1882); Agonostomus monticola (Bancroft, 1834); Mugil curema Valenciennes, 1836; Poecilia butleri Jordan, 1889; Centropomus ni- grescens Gunther, 1864; Lutjanus novemfasciatus Gill, 1862; Eucinostomus currani Zahuranec, 1980; Dormi- tator latifrons (Richardson, 1844); Eleotris picta Kner, 1863; Gobiomorus maculatus (Gunther, 1859); Awaous banana (Valenciennes, 1837); Gobionellus microdon (Gilbert, 1892); Trinectes fonsecensis (Gunther, 1862). Va- lues of b ranged from 2.912 to 3.432. The results revealed that length-weight relations for all species were highly correlated; likewise, length-length relations for all fi shes also showed high correlation. This study presents for the fi rst time, length-weight parameters for two species and length-length relations for six species.

El hueso urohial de los peces Gerreidae (Teleostei: Percoidei) de América y su aplicación taxonómica

El urohial es un hueso impar de origen dermico, ubicado en el centro de la mandibula inferior de los peces teleosteos y constiyuye un elemento fundamental en el mecanismo de apertura bucal. El estudio comparativo del hueso urohial en los Gerreidae americanos, sustenta la idea de que dicha estructura manifesta formas distintivas que pudieran ser de gran utilidad para la diferenciacion taxonomica a nivel de generos y de especies. La presente contribucion ofrece una descripcion de las caracteristicas que distinguen la morfologia del hueso urohial de cinco especies selectas representativas de cuatro generos de la familia Gerreidae en America: Diapterus (D. brevirostris), Eucinostomus (E. dowii), Eugerres (E. lineatus y E. mexicanus) y Gerres (G. cinereus).

Checklist of the marine and estuarine fishes of Chiapas, Mexico

A systematic checklist is presented for the marine estuarine fishes of Chiapas, Mexico, including notes on their zoogeography and conservation status. The checklist includes 379 species, two classes, 30 orders, 91 families, and 207 genera. Actinopterygii is the most diverse class (323 species, 181 genera, 72 families, and 23 orders), while Chondrichthyes (56 species, 26 genera, 19 families, and seven orders) is the least diverse class. Perciformes is the richest order (175 species, 98 genera, and 32 families), including seven families representing 32.2% of the total fish diversity reported here: Sciaenidae (25 species), Carangidae (21), Gobiidae (20), Haemulidae (14), Epinephelidae (11), Dactyloscopidae (10), and Gerreidae (10). Based on a taxonomical review of specimens in fish collections and literature-verified records, the list is composed of marine-stenohaline (46.7%), marine-euryhaline (48.8%), primary freshwater (1%), secondary freshwater (2.6%), and diadromous (0.2%) species. The ichthyofauna showed greater zoogeographic affinity to the Mexican (81.5%) and Panamic (80.5%) provinces, while 48 species are circumtropical, four amphipacific, five amphiamerican, and one exotic (Oreochromis niloticus). Based on the IUCN Red List, 259 species are of “Least Concern”, 18 are “Near Threatened”, 11 are “Vulnerable”, two are “Critically Endangered” (Pristis pectinata and P. pristis), and one is “Endangered” (Rhincodon typus); 23.2% are “Not Evaluated” or “Data Deficient”. Three species are under “Special Protection” and another three are “Threatened” under Mexican law NOM-059-SEMARNAT-2010. Nearly 75% of the teleostean and 25% of the cartilaginous fishes are of commercial value. Taxonomic identifications should be updated and the geographic distributions of Chiapas’ coastal fish species should be documented in order to design and implement effective management and conservation programs.

Identificación de zonas propicias para el desarrollo larval de la macarela del Pacífico(Scomber japonicus) en la porción sur de la Corriente de California

espanolEl tamano larval es una variable importante para entender los cambios en el desarrollo y la identificacion de un entorno adecuado para el crecimiento y la supervivencia larval. Las larvas de la macarela del Pacifico (Scomber japonicus) presentan un lento crecimiento durante las primeras fases del desarrollo (6-8 mm de LE); posteriormente, la velocidad de crecimiento aumenta, pero el desarrollo depende principalmente de la temperatura y del alimento. El objetivo del presente trabajo fue identificar las zonas y temporadas propicias para el desarrollo larval de S. japonicus, en relacion a la temperatura superficial del mar y la biomasa del zooplancton, frente a la costa occidental de la Peninsula de Baja California (~25-32°N) del 2006 al 2010. Las larvas de la macarela del Pacifico mostraron la mayor amplitud en su distribucion espacial en primavera, pero con mayor abundancia restringida frente a Punta Eugenia (~28°N) durante el verano. Los cambios en su distribucion, estuvieron bajo la influencia del flujo geostrofico y la variabilidad termica. El analisis de regresion lineal permitio identificar zonas propicias para el desarrollo de larvas, con un menor desarrollo en primavera, relacionado con un intervalo estrecho de temperaturas y niveles de biomasas del zooplancton comparativamente bajos. En contraste, durante el verano el mayor incremento en la altura del cuerpo (s) fue relacionado con un amplio intervalo de temperaturas, mientras que su baja variabilidad (error estandar) coincidio con altos niveles de biomasa del zooplancton. Se considera que las condiciones termicas y de disponibilidad de alimento favorecen un optimo desarrollo larval particularmente en la epoca de verano. EnglishLarval size is considered as an important variable to understand the changes in larval development and identification of a suitable environment for larval growth and survivor. Larvae of the Pacific mackerel (Scomber japonicus) have a slow growth during the early stages of development (6-8 mm SL); subsequently, the growth rate increases, but the development depends mainly on the temperature and food. The aim of this study was to identify the areas and seasons favorable for larval development of S. japonicus, in relation to the sea surface temperature and the zooplankton biomass, off the west coast of the Baja California Peninsula (~25°-32°N) from 2006 to 2010. Larvae of the Pacific mackerel showed the greatest amplitude in their spatial distribution during spring, but with greater restricted abundance compared to Punta Eugenia (~28°N) during summer. Changes in its distribution were influenced by geostrophic flow and thermal variability. Linear regression analysis allowed to identify areas favorable for larvae development, with a lower development in spring, related to a narrow range of temperatures and levels of comparatively low zooplankton biomass. In contrast, during summer the largest increase in body height (s) was related to a wide range of temperatures, while its low variability (standard error) coincided with high levels of zooplankton biomass. It is considered that thermal conditions and food availability, favor an optimum larval development, particularly during the summer season.

Comparative anatomy of the caudal skeleton of lantern fishes of the genus Triphoturus Fraser-Brunner, 1949 (Teleostei: Myctophidae)

The caudal skeleton provides important information for the study of the systematics and ecomorphology of teleostean fish. However, studies based on the analysis of osteological traits are scarce for fishes in the order Myctophiformes. This paper describes the anatomy of the caudal bones of 3 Triphoturus species: T. mexicanus (Gilbert, 1890), T. nigrescens (Brauer, 1904) and T. oculeum (Garman, 1899). A comparative analysis was performed on cleared and stained specimens to identify the differences and similarities of bony elements and the organization of the caudal skeleton among the selected species. Triphoturus mexicanus differs from T. oculeum in the presence of medial neural plates and a foramen in the parhypural, while T. nigrescens differs from their congeners in a higher number of hypurals (2 + 4 = 6) and the separation and number of cartilaginous elements. This osteological description of the caudal region allowed updates to the nomenclature of bony and cartilaginous elements in myctophids. Further, this study allows for the recognition of structural differences between T. mexicanus and T. oculeum, as well as the major morphological distinction between T. nigrescens and their sister species.