Reproductive strategies of two sympatric species of Hyalella Smith, 1874 (Amphipoda,Dogielinotidae) in laboratory conditions

This study was performed in order to test theoretical predictions that sympatric species might show different reproductive strategies to facilitate their coexistence. The duration of precopulatory mate‐guarding behaviour, body size of ovigerous females, embryonic and postembryonic development time, fecundity, and viability of the sympatric amphipod species Hyalella pleoacuta and H. castroi were investigated under laboratory conditions (19±1°C and 12 h light/dark photoperiod). Specimens were collected with nets in autumn and spring 2004, and summer and winter 2005 in the Vale das Trutas, São José dos Ausentes County, southern Brazil, and transported to the laboratory. Both species of Hyalella showed similar reproductive strategies, especially in respect to the duration of the precopula, duration of the embryonic period, and fecundity. However, these species differed in body size of ovigerous females, duration of the postembryonic period, viability, and body size of juveniles that remained in the marsupium and those released by females. These differences in the reproductive traits of H. pleoacuta and H. castroi may facilitate their coexistence in nature.     

Reproductive biology of two species of Hyalella Smith, 1874 (Crustacea: Amphipoda: Hyalellidae) from southern Brazil

Reproduction is a critical event in the life cycle of animals, and a high amount of energy is allocated to it. The aim of this study was to characterize the reproductive biology of two recently described species of Hyalella from the north-east region of state of Rio Grande do Sul in southern Brazil. The specimens were collected during 12 months from a stream source (Hyalella georginae) and from a water reservoir (H. gauchensis), in Palmeira das Missões municipality, state of Rio Grande do Sul. Upon sampling, ovigerous females and pairs in precopulatory behaviour were separated into microtubes. In the laboratory, the cephalothorax length (CL in mm) of all specimens was measured. Male size at onset of sexual maturity was larger than that of the females, in both species. There was a correlation between the size of paired males and females: larger males carried larger females, in both Hyalella species. Precopulatory pairs were found throughout the year; however, H. georginae had a higher frequency in spring, and H. gauchensis in autumn. There was a positive correlation between the CL of ovigerous females and the number of eggs/juveniles. A reduction in the number of eggs throughout the embryonic development was observed in H. georginae. The average fecundity of H. georginae was significantly higher than H. gauchensis. The differences between the reproductive biology of these species may be related to the physical and environmental conditions at which they are exposed in their habitats.     

Abundance variations and life history traits of two sympatric species of Neotropical annual fish (Cyprinodontiformes: Rivulidae) in temporary ponds of southern Brazil

We investigated abundance variations and life history traits (body size, sex ratio, length–weight relationships and condition factor) of two species of annual fish (Austrolebias minuano Costa and Cheffe and Cynopoecilus fulgens Costa) in temporary ponds of southern Brazil. Six samples were taken from small temporary ponds during three annual seasons over 2 years (2008–2009). A total of 104 individuals of A. minuano and 433 individuals of C. fulgens were collected. The abundance of both species tended to decrease from autumn to spring in the 2 years. The overall sex ratio of A. minuano and C. fulgens were 1.0 male to 1.8 females and 1 male to 1.04 females, respectively. Juveniles of both species occurred only in autumn over the two years and no adult was observed during this season. While the length–weight relationship of A. minuano indicated hyperallometric growth, the relationship of C. fulgens indicated values close to isometric growth.     

A new species of Hyalella from the Patagonia,Chile, with redescription of H. simplex Schellenberg, 1943 (Crustacea: Amphipoda)

The species of Hyalella living in the southern extreme of South America have several common morphological features. The uniqueness of this morphology presents a good argument for inferring phylogenetic relationships among them. The species are concentrated, although not exclusively, in the Patagonia of Chile and Argentina. The group is called here ' patagonica complex'. These species are not the only Hyalella present in the area, however. Hyalella simplex Schellenberg, 1943, with no morphological affinities to the patagonica complex is also present, and is one of the few other species outside the complex living in the continental extreme south of South America. Hyalella simplex is redescribed in this paper. Two species of the patagonica complex have been recorded for the area: H. neonoma Stock and Platvoet, 1991 and H. araucana Grosso and Peralta, 1999. H. fossamancinii Cavalieri, 1959, another species in the complex, is found high in the Andes. The new species H. franciscae described in this work is added to the complex.     

A new species of Hyalella from Colombia,and the redescription of H. meinerti Stebbing, 1899 from Venezuela (Crustacea: Amphipoda)

The new species H. quindioensis is described from Colombia. This species is close to H. paramoensis Andres, 1988 also in Colombia. Hyalella meinerti Stebbing, 1899 is figured and redescribed. The type locality for this species is Venezuela. However, it has a wide distribution including Colombia, Peru, Ecuador and Brazil.     

Two new species of Niphargus (Crustacea: Amphipoda) from Iran

Two Niphargus species, Niphargus khayyami sp. nov. and Niphargus khwarizmi sp. nov., are morphologically analysed and described. Both species are found in western Iran, which represents the easternmost border of the distributional area for this subterranean amphipod genus. We were unable to attribute N. khayyami sp. nov. to any of 80 Niphargus species that were analysed for 28S ribosomal DNA sequences; sequencing of N. khwarizmi sp. nov. failed. Niphargid findings from west Asia recorded in 5 years imply that almost one half of the range of this large freshwater amphipod genus is still unexplored. http://www.zoobank.org/urn:lsid:zoobank.org:pub:9E9E7CC9-83E2-419F-A394-57197305E1EF     

Description of two new species of Guernea (Crustacea,Amphipoda, Dexaminidae) from Japan,with tentative revision of subfamily Prophliantinae

Guernea minor sp. nov. and G. ezoensis sp. nov. are described from Japan. Based on these new species and the literature, a tentative revision of the subfamily Prophliantinae is proposed. The subgenus Prinassus of the genus Guernea is invalidated. The subgenus Haustoriopsis of the genus Guernea is re-elevated to a separate genus from Guernea. Dexaminoculus is transferred from Prophliantinae to Dexamininae.     

Spatial niche variation in two sympatric species of Bokermannohyla (Anura: Hylidae) in southeastern Brazil

We studied patterns of microhabitat use by adults of two sympatric Bokermannohyla species at the Reserva Particular do Patrimônio Natural Santuário do Caraça, southeastern Brazil. We selected three streams, one where both species occurred in syntopy and the other two where each one occurred alone. We sampled 150-m transects in each stream throughout 1 year, recording microhabitat features for each frog located (substrate type, height and distance from water). Microhabitat availability varied between dry and wet seasons in all streams, and overall microhabitat diversity changed in two streams. Bokermannohyla nanuzae seemed to have a niche contraction in the presence of Bokermannohyla martinsi, but this only happened during the dry season. Microhabitat requirements during the wet season may be closely linked to similar reproductive needs that probably represent a strong selective pressure, forcing niche overlap.     

Three new species of Gammarus from Shaanxi,China (Crustacea: Amphipoda: Gammaridae)

Three new species, Gammarus shenmuensis n. sp., G. murarius n. sp. and G. martensi n. sp. are described, based on the collections from the Shaanxi Province of China. The morphological characters that distinguish these different species are presented. Distribution data on these gammarids are also given.     

A new genus and species of Caprellidae (Crustacea: Amphipoda) from Kiribati

ABSTRACT

Luisacaprella eliae gen. nov, sp. nov. (Crustacea, Amphipoda, Caprellidae) is described bwct ased on specimens collected from Kiribati, Pacific Ocean. The new genus is close to Aciconula but can be mainly distinguished by the following characteristics: (1) pereonites 6 and 7 are fused in Luisacaprella gen. nov. while they are separated in Aciconula; (2) the setal formula of mandibular palp is 2-x-1 in Luisacaprella and 1-x-1 in Aciconula; (3) pereopods 3 and 4 are two-articulate in males and females of Luisacaprella, whereas there is sexual dimorphism in Aciconula, and males have pereopods 3 and 4 two-articulate while females have pereopod 3 two- or three-articulate and pereopod 4 four-articulate. The new species L. eliae is additionally characterised by its tiny size (<3 mm). The new taxon was collected from dead branching coral of shallow waters (3–32 m). Further studies targeting small caprellids which could easily be overlooked from substrates such as sediments and dead corals are needed to properly understand the global caprellid diversity of tropical and temperate areas.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:1F5A24BE-A7AC-4D3C-A087-F7284F84A2DC     

A new landhopper species of Myanmarorchestia (Crustacea: Amphipoda: Talitridae) from Yunnan,China

A new landhopper talitrid, Myanmarorchestia nunomurai Nakano and Morino, sp. nov., from Yunnan Province, China is described. Since species of Myanmarorchestia were known only from Mt. Victoria of the Arakan Mountains of Myanmar, this is the first record of the genus from China. Myanmarorchestia nunomurai is characterised by its coxal gills on gnathopod 2 to pereopod 6 without filamentous projections while the other congeners from Myanmar possess some/all of the coxal gills with filamentous projections. Additionally, M. nunomurai can be diagnosed by the sexually dimorphic uropod 2, of which the outer ramus bears a robust seta on the midlateral surface and a few rows of small teeth on the middle to distodorsal surface.

http://zoobank.org/urn:lsid:zoobank.org:pub:3C014FFC-F4D6-4F18-8188-33672367ABB1     

Biogeography of amphipods (Crustacea: Amphipoda: Gammaridae) from the central Zagros Mountains,Iran, with descriptions of two new species

Seven species of gammarid amphipods were studied in the relatively small province of Charmahal-Va-Bakhteyari in the central Zagros Mountains, Iran. Of these, four are previously known (Gammarus proiectus, G. komareki, G. syriacus and G. balutchi), one is a new record for the region (G. pseudosyriacus) and two are new species (G. lordeganensis and G. bakhteyaricus). From the taxonomic point of view, head microsculpturing characters were found to be reliable as discriminating sets of characters useful in species identification. Habitat diversification and climatic fluctuations appear to be the main factors for species diversity of the area, and the Zagros Mountains act as a geographical barrier to species distribution.     

Elevation of two eastern Atlantic varieties of Ampelisca brevicornis (Costa, 1853) (Crustacea,Amphipoda) to full specific rank with redescription of the species

Two species of Ampelisca, Ampelisca pectenata and Ampelisca cavicoxa, are studied here. These species were originally taken to be varieties of Ampelisca brevicornis, but they proved upon closer study actually to be different species. They are redescribed here in detail, and raised to the status of species. These two species have hitherto only been known to inhabit tropical Atlantic areas. Now for the first time they have been recorded on the French Atlantic coast, which shows that they have a wider geographical distribution than was previously assumed. Some biological data are also given which add to the knowledge available about this family of Amphipoda. Deux espèces d'Ampeliscidae sont étudiées dans ce travail, Ampelisca pectenata et Ampelisca cavicoxa. A l'origine, elles ont été décrites comme variétés de Ampelisca brevicornis, mais une étude détaillée montre qu'il s'agit d'espèces différentes. Elles ont donc étéentièrement redécrites et élevées au rang d'espèces. Ces espèces n'étaient connues jusqu'àprésent qu'en régions tropicales Atlantiques. Pour la première fois elles sont signalées sur les cô     

The occurrence of the genus Ingolfiella (Crustacea,Amphipoda) in South Africa,with description of a new species

Abstract

The occurrence in South West Africa, i.e. within the confines of the Republic of South Africa, of the Amphipod genus Ingolfiella Hansen is recorded. The species is subterranean, is larger than any of the previously known species, and is described as I. opisthodorus sp. n. It is compared with I. leleupi Ruffo from the Congo and Northern Rhodesia. The majority of the specimens seem to be females although none has even a trace of oostegites or brood lamellæ. They exhibit a marked dimorphism of the first pair of pleopods, chiefly in specimens exceeding 14 mm. in body length; a juvenile form of this pair occurs in specimens measuring 12 to 14 mm. A few supposed males, among the last specimens to be collected (in June), are smaller than the supposed females but the two pairs of gnathopods are relatively larger and of a different form.     

A new species of amphipod of the genus Neomegamphopus (Crustacea,Amphipoda, Neomegamphopidae) from Rodrigues,Indian Ocean

A new species of Neomegamphopus Shoemaker is described from Rodrigues, Indian Ocean. The systematics of the Neomegamphopidae from the Indian Ocean is discussed and a key to the species from that ocean is provided.     

Revision of Stegosoladidus Barnard and Karaman, 1987 (Crustacea: Amphipoda: Stegocephalidae), redescription of two species and description of three new species

Stegosoladidus simplex (K. H. Barnard, 1930) and S. ingens (Chevreux, 1906) are both figured and redescribed. Three new species (Stegosoladidus antarcticus, S. complex and S. debroyeri) are described. The terminology used for classification of both setae and different setae arrangements is discussed, and the main types of setae are figured.     

Larval development of the fiddler shrimp,Metapenaeopsis stridulans (Alcock, 1905) (Decapoda: Penaeidae) reared in the laboratory

Larvae of Metapenaeopsis stridulans (Alcock, 1905) from Malaysia were successfully reared in the laboratory from the egg to the 1st post-larval stage. The larvae developed through six naupliar, three protozoeal and four mysis stages. The morphology of all these larval stages is described and figured.