Genetic diversity of freshwater crabs (Brachyura: Sesarmidae) from central Jamaica with description of a new species

Jamaica is the only island of the Greater Antilles where freshwater streams are not populated by representatives of the old lineage of freshwater crabs, the Pseudothelphusidae. Instead, a very diverse fauna of endemic sesarmid crabs inhabits freshwater and terrestrial habitats throughout the island, thereby showing complete independence from the sea. They have been reported thriving in bromeliad leaf axils, rock rubble, empty snail shells, caves and mountain streams. Otherwise, the Sesarmidae are typical inhabitants of soft‐sediment littoral habitats like marshes and mangroves. For many years, crabs from Jamaican mountains streams had been considered to belong to a single species, Sesarma bidentatum Benedict . However, recent morphological and molecular studies have shown that crabs from mountain streams of different regions of the island belong to different species. Consequently, four new crab species have been described over the last 10 years. In this study, we give evidence that freshwater streams in central Jamaica also host two different species of crabs. In streams draining to the north we exclusively found the species S. windsor Türkay and Diesel, , while streams draining to the south were inhabited by a closely related but undescribed species of crab. The southern species is here described as new and is referred to as Sesarma meridies sp. n. Morphological and molecular (12S and 16S mtDNA) evidence is provided that allows these two species of freshwater crabs from central Jamaica to be distinguished. The species richness of Jamaican endemic sesarmids thereby increases to 10, which makes the island unique in terms of its diversity of land‐dwelling crabs.     

Comparative morphology of the foregut of four Gnathophausia species (Crustacea; Mysidacea; Lophogastrida). Relationships with other taxa

The features of the foregut of Gnathophausia ingens Dohrn, 1870, G. zoea W.-Suhm, 1875, G. longispina G. O. Sars, 1883 and G. gracilis W.-Suhm, 1875 (Crustacea, Mysidacea, Lophogastrida, Lophogastridae) are described, based on scanning electron microscopy. Comparisons are made with the foregut of related taxa, particularly with Eucopia, the only genus constituting the second family (Eucopiidae) of the Lophogastrida. The foreguts of Gnathophausia and Eucopia exhibit (1) common features, which might be characteristic of the sub-order Lophogastrida, (2) more similarities with those of the Decapoda than those of the sub-order Mysida. But preliminary observations suggest that the stomach is obviously smaller than that of the similarly sized Decapoda. The foregut of Gnathophausia is morphologically unique to this genus, although each species exhibits small specific differences.     

Intrinsic properties and extrinsic neurohormonal control of crab cardiac hemodynamics

This report provides the first direct measurements of the stroke volume and total cardiac output of crustacean hearts, as recorded from a semi-isolated in vitro preparation. The responses to mechanical perturbations, changes in preload and afterload, show that these hearts do not possess automatic compensatory Frank-Starling-like mechanisms. Heart rate, reflecting the burst rate of the cardiac ganglion, is minimally affected by stretch. On the other hand, these hearts are exquisitely responsive to the neurohormones of the pericardial organs. Serotonin, CCAP and proctolin all produce positive chronotropic and inotropic effects, but the responses to each are unique. Two FMRFamide peptides were positively chronotropic, but negatively inotropic.     

Expanding the taxonomic conundrum: Three new species of groundwater crustacean (Syncarida,Bathynellacea, Parabathynellidae) endemic to the Iberian Peninsula

Two new species of the genus Iberobathynella and one new species of the cosmopolitan genus Hexabathynella are described from the Iberian Peninsula. The three new species were found in the groundwater of caves and the gravelly bank of a river, two species in the north of Spain (Cantabria and Burgos) and one in the south (Sevilla). The two new species of the genus Iberobathynella present a unique combination of characters. These character combinations for the species from Cantabria are: thoracopod 8 female with wrinkled cuticle and two teeth; seven spines on the furca; nine spines on the sympod, three barbed and one plumose seta on the exopod and two barbed setae on the endopod of the uropod; maxilla with 0, 0 and 15 setae on the three segments, respectively; five teeth on the pars incisiva and six teeth on the pars molaris of the mandible and seven segments on the antennule. The combinations of characters for the species from Burgos are: antennule with seven segments; segment 5 of the antennule with one aesthetasc; mandible with four and five teeth on the pars incisiva and pars molaris respectively; maxillule with one seta on segment 1 and 14 setae on segment 3; segment 1 of the endopod of the thoracopod 1 with two setae; uropod with six spines on the sympod, four barbed setae and one plumose seta on the exopod and no setae on the endopod; furca with five spines and the thoracopod 8 female with wrinkled cuticle and two teeth. This last species has an exclusive character for the genus: the absence of setae on the endopod of the uropod. The new species of the genus Hexabathynella has six spines of similar length on the sympod of the uropod (in all other species within the genus the distal spine is longer than the others); the form of the antennal organ in the males is shown to be a new unique character for the genus; the maxilla has three and 13 setae on segments 2 and 3, respectively; the uropod has six spines on the sympod, three barbed setae on the exopod and two smooth setae on the endopod, the endopod is twice as long as the exopod and the shape of the female thoracopod 8 is unique.     

Skara hunanensis a new species of Skaracarida (Crustacea) from Upper Cambrian (Furongian) of Hunan,south China

The fossils of Orsten-type preservation are as famous as Chengjiang Fauna in the world,but it was not until 2005 that the Orsten-type fossils represented by Skaraearida and Phosphatocopida were first reported to be found in western Hunan,South China. Here,we report the systematic paleontology of all the exquisitely preserved specimens belonging to Skaraearida.They were found at a same horizon of Upper Cambrian (Furongian) in Wangcun section,western Hunan,south China,assigned to a new species Skara huna- nensis herein.Skara hunanensis is characterized by small,soft-integumented,marine forms with slender,annulate body;labrum large and ventrocaudally directed;uniramous antennulae;biramous antennae and mandibulae;maxillas and maxillipeds of the same shape;all postantennular limbs join a short cephalic filter apparatus.The body has two tagmata:a cephalon with five pairs of well developed ap- pendages and a trunk composed of 11 ring-shaped conical segments.     

A new species of the genus Vercoia from Okinawa Island,Japan (Crustacea,Decapoda, Caridea,Crangonidae), with descriptions of its zoeal stages

A new crangonid shrimp and its four zoeal stages are described and illustrated in detail from Okinawa Island, Japan. The new species of Vercoia is readily distinguished from V. gibbosa Baker, 1904 Baker W. H 1904 Notes on South Australian decapod Crustacea Transactions and Proceedings and Report of the Royal Society of South Australia, 28, 146–161, pls 27–31  [Google Scholar], V. socotrana Duris, 1992 Duris, Z. 1992. Revision of Vercoia Baker (Crustacea: Decapoda: Crangonidae). Invertebrate Taxonomy, 6: 1437–1457.  [Google Scholar] and V. japonica Komai, 1995 Komai, T. 1995. Vercoia japonica, a new species of crangonid shrimp (Crustacea: Decapoda: Caridea) from Japan. Natural History Research, 3: 123–132.  [Google Scholar], in adult morphology, by the bilobed anterior expansion of the hepatic carina of the carapace, the notched mid-dorsal carina on the fifth abdominal somite, and the presence of the distoventral tooth on the ischium of the second pereopod. The larvae of the new species which are the first larvae of a species assigned to Vercoia to be described, are very similar to those of species of Philocheras, but they differ in the setation of the endopods of the maxillule and maxilla. A key to the adult species of Vercoia is provided.     

A revision of the Caridina gracilirostris De Man, 1892, species group,with descriptions of two new taxa (Decapoda; Caridea; Atyidae)

Re‐examination of the syntypes of Caridina gracilirostris De Man, 1892 De Man, J. G. 1892. “Decapoden des Indischen Archipels.”. In Zoologische Ergebnisse einer Reise in Niederlandisch Ost‐Indien Edited by: Weber, M. Vol. 2, 265–527. Plates 15–29 [Google Scholar], shows that the type series is composed of three species. These three species are similar in the form of the rostrum, but can be differentiated easily by a combination of rostral formula and sexual appendages. To stabilize the taxonomic status of these species, a lectotype for C. gracilirostris is selected. A lectotype for Caridina appendiculata Jalihal and Shenoy, 1998 Jalihal, D. R. and Shenoy, S. 1998. “Taxonomic revision of some Indian prawn species of genus Caridina H. Milne Edward, 1837 (Atyidae).”. In Proceedings and abstracts of the Fourth International Crustacean Congress, 128–129. Amsterdam, , Netherlands: The Crustacean Socrety.  [Google Scholar], is also designated from among the remaining syntypes of C. gracilirostris. A new species, C. neglecta, is described. Caridina gracilirostris and C. gracilima Lanchester, 1901 Lanchester, W. F. 1901. On the Crustacea collected during the “Skeat” expedition to the Malay Peninsula.. Proceedings of the Zoological Society of London, 1900([1901]): 533–574.  [Google Scholar], are redescribed and figured, and C. appendiculata is transferred to the C. nilotica species group. A new species group is also recognized for C. gracilirostris, C. neglecta, C. gracilima, and a new species, C. longifrons. The C. gracilirostris species group is defined here as taxa possessing a rostrum with subapical teeth, fewer than 10 dorsal teeth, and without any postorbital teeth.     

A revision of the genus Platythelphusa A. Milne-Edwards, 1887 from Lake Tanganyika,East Africa (Decapoda: Potamoidea: Platythelphusidae)

The genus Platythelphusa is revised and six species are recognized. These species are P. armata A. Milne-Edwards, 1887, P. maculata (Cunnington, 1899), P. conculata Cunnington, 1907, P. tuberculata Capart, 1952, P. polita Capart, 1952 and P. echinata Capart, 1952. A seventh taxon, P. denticulata Capart, 1952 is considered here to be a junior synonym of P. conculata. A diagnosis for each species is provided and most are figured from the type. Keys to the families of African freshwater crabs and to the genus Platythelphusa are also provided.     

Gastropod shell utilisation pattern by the hermit crab Clibanarius symmetricus (Anomura: Diogenidae) in an Equatorial Amazon estuary

Clibanarius symmetricus is a diogenid hermit crab that is highly abundant in rocky intertidal environments, including the rock outcrops of Amazon estuaries. This study characterises the C. symmetricus shell utilisation pattern in the Marapanim River estuary, Pará, Equatorial Amazon, based on the hypothesis that occupancy patterns would differ, in relation to biometry and diversity of occupied shells, from those of other regions in the range of this species due to the distinct and unique environmental characteristics of equatorial estuaries. Monthly samplings were carried out from August 2006 to July 2007, in the upper and lower areas of the mid-littoral during low tides. A total of seven gastropod species were found as shells occupied by hermit crabs: 93.33% were Thaisella trinitatensis shells, 2.00% Nassarius vibex, 2.00% Neritina virginea, 1.33% Natica marochiensis, 0.67% Parvanachis obesa, and, occasionally, Littorina flava and Phalium granulatum shells, each with only one occurrence (0.33%). Juveniles [cephalothoracic shield length (CL) of less than 3.6 mm] occupied a higher variety of shells, while adults occupied shells with larger meristic variation. Males occupied larger shells. The length of the animal was influenced by shell measurements (total width, aperture width and weight). Clibanarius symmetricus showed occupancy patterns generally similar to those of specimens of the same species previously studied in the Brazilian subtropical region, and this occupancy is explained by shell availability, shell size and weight, and hermit size. However, this study showed lower occupied shell species diversity, and the species with highest occupancy frequency (T. trinitatensis) was not reported in any previous studies on this hermit crab. In addition, the studied population differed in occupancy patterns, with differences between males and females, and between juveniles and adults.