Michel E. Hendrickx

EMBRYOLOGY OF DECAPOD CRUSTACEANS I. EMBRYONIC DEVELOPMENT OF THE MANGROVE CRABS GONIOPSIS PULCHRA AND ARATUS PISONII (DECAPODA: BRACHYURA)

Abstract The complete embryonic development of the mangrove crabs Goniopsis pulchra and Aratus pisonii is described based on morphological features observable in live eggs. Periods of development are defined in steps of 48 hours each and in relation to the time of embryonic development. Eight periods were described and illustrated for Aratus pisonii and nine for Goniopsis pulchra. Embryo development from recently spawned eggs to hatching lasted 14 days for Aratus pisonii and 15 for Goniopsis pulchra at 26–28°C. The embryonic development of the two species was very similar; growth was synchronous, appendages were formed during the same periods, complexity of abdominal and ocular processes were chronologically comparable. Goniopsis pulchra eggs were slightly larger, while in Aratus pisonii the digestive gland was easier to observe in later periods and the telson grew larger. Cromatophores were more evident in Aratus pisonii embryos, especially those of the telson.

EXTERNAL DESCRIPTION OF THE EMBRYONIC DEVELOPMENT OF THE PRAWN, MACROBRACHIUM AMERICANUM BATE, 1868 (DECAPODA, PALAEMONIDAE) BASED ON THE STAGING METHOD

The embryonic changes during the development of the freshwater prawn, Macrobrachium americanum are described from observations made on live embryos based on the percentage-staging method. Eggs were observed with a stereomicroscope to obtain descriptions of embryonic periods. This prawn has an incubation time of 18 days at 24°C. Ten periods are described and illustrated. A comparison of this developmental process with those of congeneric species is included. Se describen los caracteres externos del desarrollo embrionario del langostino dulceacuicola Macrobrachium americanum tomando como criterio el metodo de estadios fijos basado en porcentajes. Los huevecillos fueron observados en vivo con un microscopio estereoscopico y se descibe cada periodo de desarrollo. Los huevecillos tardan 18 dias en incubarse a una temperatura de 24°C. Diez periodos se describen e ilustran. Se compara el desarrollo con el de algunas especies cercanas.

Abnormal rostrum and telson in two species of penaeid shrimp (Decapoda, Dendrobranchiata, Penaeidae) from the Pacific coast of Mexico

[Morphological abnormalities were observed in two specimens of penaeid shrimp collected along the east coast of the Gulf of California, Mexico. A bifid rostrum was observed in the brown shrimp, Farfantepenaeus californiensis and a bifid telson in the white shrimp, Litopenaeus vannamei . Des anomalies morphologiques ont ete observees chez deux specimens de crevettes Peneides recoltees le long de la cote est du golfe de Californie, Mexique. La crevette brune, Farfantepenaeus californiensis , presente un rostre bifide et la crevette blanche, Litopenaeus vannamei , un telson bifide. , Morphological abnormalities were observed in two specimens of penaeid shrimp collected along the east coast of the Gulf of California, Mexico. A bifid rostrum was observed in the brown shrimp, Farfantepenaeus californiensis and a bifid telson in the white shrimp, Litopenaeus vannamei . Des anomalies morphologiques ont ete observees chez deux specimens de crevettes Peneides recoltees le long de la cote est du golfe de Californie, Mexique. La crevette brune, Farfantepenaeus californiensis , presente un rostre bifide et la crevette blanche, Litopenaeus vannamei , un telson bifide. ]

Abundance and diversity of macrofauna (fish and decapod crustaceans) in Penaeus vannamei culture ponds in Western Mexico

Abstract Polyculture involving shrimp and fish has not been developed in western Mexico. Shrimp farming along the west coast of Mexico has been estimated to occupy a total of 8000 ha, producing about 0.90 tons ha −1 in 1993. Abundance and diversity of macrofauna (fish and decapod crustaceans) associated with culture (MAC) of Penaeus vannamei were determined twice in a year, in a shrimp farm located 25 km south of Mazatlan, Sinaloa, SE Gulf of California, Mexico. A total of 4978 specimens of MAC was obtained; 2355 in June 1993 and 2623 in January 1994, totalling about 115 kg of fresh weight (0.34 to 0.87% of shrimp harvest). Fish represented 98.3% and 98.0% of specimens and 90.2–93.5% of total fresh weight; the rest were swimming crabs ( Callinectes ). The abundance of Pomadasys macracanthus, Lile stolifera , and Dormitator latifrons mexicanus was high and remarkably constant at both harvests. Maximum diversity was observed in winter (January 1994). Dominance by fresh weight reflects the importance of Pomadasys macracanthus in both cycles, and of Cynoscion xanthulus in the second. Largest fish were Gobiomorus maculatus (19.0 cm total length (TL)) and Elops affinis (36.5 cm TL). When comparing sizes, fish showed either a very clear ( P. macracanthus, M. altipinnis and G. cinereus ), slight ( L. stolifera and D. latifrons mexicanus ) or obscure ( C. xanthulus ) displacement towards higher values in the second, longer cycle. Callinectes arcuatus , the only abundant decapod crustacean harvested, also showed a remarkable stability as far as population size, fresh weight and size distribution were concerned.

THE COMPLETE LARVAL DEVELOPMENT OF JOHNGARTHIA PLANATUS (BRACHYURA: GRAPSOIDEA: GECARCINIDAE) DESCRIBED FROM LABORATORY REARED MATERIAL, WITH NOTES ON THE AFFINITY OF GECARCINUS AND JOHNGARTHIA

Abstract The land crab Johngarthia planatus is an eastern tropical Pacific species with a known distribution from Mexico to Colombia. Complete larval development of the species is fully described and illustrated from laboratory-reared material. The five zoeal stages and the megalopa are compared with those of Gecarcinus lateralis lateralis from the Atlantic coast. Main differences for zoeal stages are observed in the carapace and telson lateral spines while minor differences are observed in the mouthparts setation. For the megalopa stage a difference in size of the third maxilliped exopod supports the separation of Johngarthia from Gecarcinus. A brief comparison of all known zoea I and megalopa stages of species of the Gecarcinidae is made, taking into account recent new descriptions.

The complete larval development of Pilumnus limosus (Crustacea: Decapoda: Brachyura: Pilumnidae) described from laboratory reared material

The pilumnid crab Pilumnus limosus is known from Gonzaga Bay, Baja California, Mexico, to Zorritos, Paita, Peru. Larvae from a female collected in the intertidal rocky shore in Mazatlan, south-eastern Gulf of California, Mexico, were reared in the laboratory from Zoea I to megalopa. A complete description and illustration of larval features is provided and a comparison with closely related species showing known larval development is presented. As in most species of this genus, P. limosus larval development consists of four zoeae. All features observed in P. limosus are similar to those of P. reticulatus and P. sayi. All those larvae have lateral processes on abdominal somites 2-5 (2 or 3 in other species); posteromarginal denticles on abdominal somites 2. 6 (absent in other species of the genus).

THE GENUS PARACERCEIS HANSEN, 1905 (ISOPODA, SPHAEROMATIDAE) IN THE EASTERN TROPICAL PACIFIC, WITH THE DESCRIPTION OF A NEW SPECIES

Paracerceis spinulosa sp. nov., is described from material collected along the Pacific coast of Mexico. This species was previously reported in literature as Paracerceis sp. and differs from the other two species of Paracerceis from the eastern Pacific (i.e., P. sculpta (Holmes, 1904) and P. richardsonae Lombardo, 1988) by the presence of a large, subconical median tubercle on the telson, a much higher uropodal exopod partly covered with spiny and rounded tubercles, and a distinct spinulation pattern on all pereiopods. Newly-collected material of P. sculpta and P. richardsonae provides new environmental and distributional data. Keys to the males and females of the species of Paracerceis of the eastern Pacific are provided.

An introductory survey of ecology and sensory receptors of tropical eastern pacific crustaceans

Abstract A comparative survey of sensory organs (mainly visual) of 35 species of crustaceans (Mysidacea, Stomatopoda and Decapoda) was initiated in the SE Gulf of California, Mexico, an enclosed sea which has been well studied for its physical conditions and the taxonomy of crustacean species. The purpose of this survey was to study how the perceptive capacities are conditioned by the signals arriving from their environment. Studied species were sampled from terrestrial, intertidal, subtidal and deep sea habitats. Our data indicate that down to 200 m there seems to be not much difference of skewing patterns in stomatopods. Eyes are adapted to local conditions. In crabs and stomatopods, ommatidia are aligned in a vertical array along the longer axis of the eye. Visual fields of ommatidia overlap. This could emphasize, for instance, the horizontal motion of vertical edges. Deep‐sea crustaceans still have eyes, but in the same habitat species with apparently functional eyes occur together with species with s...

Effects of the oxygen minimum zone on squat lobster distributions in the Gulf of California, Mexico

Distribution of squat lobsters of the genera Gastropthychus (one species), Uroptychus (1), Janetogalathea (1), Galacantha (1), Munidopsis (8), and Munida (7) in the Gulf of California, Mexico, was plotted vs. the localization of the Oxygen Minimum Zone (OMZ) using bottom projections of the 0.50, 0.25, 0.10, and 0.05 ml l−1 oxylines. Four fringes where oxygen concentrations were equal or lower than these concentrations were obtained, extending from the southern Gulf to about 28°–28°30′N. A total of 172 sampling locations with squat lobsters were plotted on four maps, one for each fringe, noting that with decreasing values of bottom oxygen (i.e., from 0.50 to 0.05 ml l−1) the number of locations with species included between the upper and lower boundaries of these fringes decreases as follows: 34% for 0.50, 25% for 0.25, 12% for 0.10, and 5% for 0.05 ml l−1. The upper and lower limits of the 0.05 ml l−1 fringe are recognised as threshold frontiers, acting as barriers between shallow and deep communities of squat lobsters in the area. The distribution of the localities where species have been collected with respect to the upper and lower boundaries of the 0.05 ml l−1 fringe clearly indicates a segregation pattern. Eight species of Munida (except M. perlata), and one each of Janetogalathea and Gastropthychus inhabit the shallow area, just above the OMZ core, with species of Munida generally found a rather long distance from this fringe. By contrast, species of Munidopsis, G. diomedeae and U. pubescens correspond to the deep area, i.e., below the OMZ core. It is suggested that the core of the OMZ in the Gulf of California serves as a vertical and latitudinal distribution filter, preventing species from freely migrating up and down or south and north.

Community structure of deep-water decapod crustaceans below the oxygen minimum zone in the south-east Gulf of California and analysis of environmental drivers

Despite the ecological importance of decapod crustaceans in energy transfer in marine ecosystems, little is known on their distribution below oxygen minimum zones (OMZs). To understand the spatio-temporal dynamics of benthic and benthopelagic decapod crustaceans living below the OMZ cores, four seasonal oceanographic and sledge surveys were performed in the south-east Gulf of California at depths between 730 and 2250m. Multivariate analyses indicate the existence of three major depth-related assemblages at: 800–1000, 1000–1200 and >1200m (mean trawl depth). Benthic detritivores dominated between 800 and 1000m and benthopelagic (i.e. swimming) predators dominated deeper, where dissolved oxygen (DO) values were higher. Assemblages comprised the same species throughout the year, but aggregations of smaller organisms were observed in June. DO significantly controlled the distribution of decapod crustaceans, likely through physiological exclusion of swimming species from hypoxic waters. Besides, the combined effects of DO and temperature contributed to defining the depth ranges occupied by each species. Food derived from surface-water production modulated changes in community parameters with different time lags in the different depth-related assemblages. These findings demonstrate the vulnerability of bathyal communities to the global pattern of OMZ expansion.