Gabino Rodríguez-Almaraz

Distribution of the Red Swamp Crayfish Procambarus Clarkii (Girard, 1852) (Decapoda: Cambaridae) in Mexico: An Update

ABSTRACT A study of the distribution of Procambarus clarkii in northern Mexico led to the conclusion that this crayfish is native to Central Rio Bravo and its tributary, Rio Salado, in Chihuahua, Coahuila, Nuevo Leon, and Tamaulipas. The Sierra Madre Oriental and the Meseta del Norte, with elevations of 1,000 or more m above sea level, provide barriers that have inhibited more western natural dispersion. We point out that P. clarkii is exotic in central-west Tamaulipas, central Nuevo Leon, western Chihuahua, Sonora, and Baja California, where its presence has resulted from repeated man-made introductions. The habitat preferred by this crayfish in northern Mexico is lotic (73%), with a mud bottom (62.5%), and aquatic vegetation was present in 50% of the known localities.

The coastal-estuarine copepod, Eurytemora affinis (Poppe) (Calanoida, Temoridae), from arid inland areas of Mexico: An expected occurrence?

For decades, the coastal-estuarine copepod, Eurytemora affinis (Poppe, 1880) was considered a cosmopolitan species. Recent studies have demonstrated that it represents a species complex with static morphology but with genetically recognizable forms clustered in defined geographical patterns. In North America, this species is widely distributed in coastal environments, but has been known to also colonize freshwater systems along the eastern coast of the United States and Canada. Based on serial samples collected in the Chihuahuan Desert (2003-2006) and in the State of Tamaulipas (2000-2002), in this work we report the occurrence of this coastal copepod from arid and semi-arid continental systems of northern Mexico and the southwestern United States. All records are from areas well inland: 800 km from the coast in the Chihuahuan Desert and 240-250 km in Tamaulipas. Records from these particularly dry, isolated habitats illustrate the adaptive performance of this species, which enables it to dwell in such extreme conditions. This is the first record of E. affinis from Mexico and also the southernmost one in the Americas as a freshwater form. Illustrations and morphometric data of specimens obtained in these arid and semi-arid zones are provided. The size, general morphology, and morphometry of these specimens show similarities to different sub-groups known within the species range, but some characters and ratios are outside of the known patterns, thus expanding the morphometric spectrum of this species. Hitherto, the only other finding of an estuarine coastal calanoid copepod in epicontinental freshwater environments in Mexico is that of Pseudodiaptomus marshi Wright, 1936 on the Yucatan Peninsula.

Morphology and systematic significance of the mystax, a hitherto undescribed cephalic structure of males in certain Notostraca (Branchiopoda)

Abstract We report on the morphology and occurrence of the “mystax,” an overlooked cephalic structure found in males of certain Notostraca. The mystax is a conspicuous, protuberant, dark-brownish sclerodermal stripe located on the anteroventral flange of the carapace. Histological sections show the mystax as an expansion of the exoskeleton formed by the exocuticle. Examination of exuviae revealed that the old mystax remains intact in the shed cuticle. In some Triops populations of México and Japan, large individuals bearing ovisacs exhibit a “pseudomystax,” which consists of a dark-brownish band in nearly the same position as the mystax, but it does not form a protuberant stripe. A total of 661 males and 6402 ovisac-bearing individuals from four continents were examined. The mystax was found in males of Triops australiensis from Australia, T. granarius from Japan, Triops sp. from North America, Triops sp. from Africa, and Triops sp. from Asia. The mystax is absent in all ovisac-bearing individuals of all species analyzed and in all males of Triops cancriformis (Africa, Europe, and Japan), and in all males of the genus Lepidurus. Practical and systematic implications of the mystax are discussed.

Evidence of oceanic dispersal of a disjunctly distributed amphidromous shrimp in Western North America: first record of Macrobrachium occidentale from the Baja California Peninsula

Six morphological species of the genus Macrobrachium occur in the Baja California Peninsula (M. americanum, M. digueti, M. hobbsi, M. michoacanus, M. olfersii, and M. tenellum). Their presence is an interesting topic for the systematics of the group, given that their distribution shows a distinct disjunct on the coastal plains of the northern part of the Gulf of California slope. Extensive collection of freshwater shrimp of the peninsula allowed us to discover individuals whose morphology corresponds to Macrobrachium occidentale Holthuis, 1950. This species, described in 1950 from the Pacific slope of Central America has received little atention. The type locality is in Guatemala, but it is also found in Mexico, El Salvador, Costa Rica, and Panama. In Mexico it has been reported in the states of Sinaloa, Nayarit, Guerrero, and Oaxaca. The aim of the present work is to contribute to the systematics of M. occidentale through two approaches. First, by reviewing the geographical distribution in Mexico, using taxonomic morphological revision of extensive field collections, as well as material deposited in three scientific collections. Second, through molecular genetic analysis of fragments of the mitochondrial genes 16S rRNA and cytochrome oxidase I, determine whether individuals from the peninsula belong to the same entity found on the mainland Pacific slope of Mexico or whether they form a distinct lineage. The results indicate the presence of the same genetic entity in both regions and show a disjunct distribution similar to other species of the genus in this region. We present a systematic account for M. occidentale, including a taxonomic treatment of the studied populations and a report of their genetic identity and relationships. Further, we suggest and discuss that the presence of this amphidromous species on the peninsula is explained by the oceanic dispersal hypothesis.

First records of Ergasilus cerastes (Copepoda, Poecilostomatoida) on cage-reared Ictalurus from northeast Mexico

GABINO A. RODRIGUEZ-ALMARAZ1,3), RICARDO GOMEZ-FLORES1) and JAIME RÁBAGO-CASTRO2) 1) Universidad Autónoma de Nuevo León, UANL, Facultad de Ciencias Biológicas, Av. Universidad S/N, Ciudad Universitaria, San Nicolás de los Garza, Nuevo León, CP 66451 Mexico 2) Facultad de Medicina Veterinaria y Zootecnia, Universidad Autónoma de Tamaulipas, Carretera Victoria-Mante Km. 5, Cd. Victoria, Tamaulipas, CP 87000, Mexico