Gammarus desperatus,a new species from New Mexico (Crustacea : Amphipoda)

A new species of the Amphipoda (Gammarus desperatus) is described from North Spring in Roswell, Chaves County, New Mexico. Apparently this is the same species reported erroneously as G. fasciatus Say from nearby Lander Springbrook by Noel (1954).Supported in part by NSF Grants GB-2461 and GB-6477X to W. L. MinckleySupported in part by NSF Grants GB-2461 and GB-6477X to W. L. Minckley     

Cheiriphotis trifurcata, new species (Crustacea, Amphipoda, Corophiidae, Protomedeiinae) from the Seagrass Bed of the Lower Gulf of Thailand

A new species of corophiid Amphipoda, Cheiriphotis trifurcata, collected from the seagrass bed of the Lower Gulf of Thailand, is described. Cheiriphotis trifurcata is characterized by its trifurcated tip of the modified setae on the outer ramus in male pleopod 3. In this paper, the new species is fully described and compared with related species and a complete key of the 16 valid species in the genus Cheiriphotis is given.     

Leucon parasiphonatus,a new species (Crustacea: Cumacea: Leuconidae) from Antarctic waters

Six specimens ofLeucon parasiphonatus n. sp. were collected at depths ranging from 15 to 424 m in the vicinity of King George Island (South Shetland Islands, Antarctica) and the south eastern Weddell Sea.Leucon parasiphonatus belongs to the subgenusLeucon and differs from the other already known antarctic and Subantarctic species of the genus, in the absence of a serrated dorsomedian line and in the presence of a long pseudorostrum with several fine setae at its tip, surrounding the very long branchial siphon. The surface of the carapace is granulated; the carapace displays no teeth except for a few at its antero-lateral margin and at its ventral margin. The species most similar toLeucon parasiphonatus isLeucon siphonatus, reported from Mediterranean and North Atlantic waters.     

Micropacteridae, a new family of Remipedia (Crustacea) from the Turks and Caicos Islands

Recent diving explorations of anchialine caves on the Turks and Caicos Islands yielded a rather small and slender new species of Remipedia. Micropacter yagerae n. gen., n. sp. is distinguished from all other species of nectiopod remipedes by a number of autapomorphic characters, including an oval body terminus with fused segments, unequal pairs of terminal claws on maxilla and maxilliped, an almost complete reduction of sternal bars and pleurotergites, molar processes with relatively few, but strong spines, and frontal filaments with bifurcate processes. Based on the unique combination of derived and primitive characters, we propose to erect a new family, Micropacteridae, for this new species and genus of Remipedia. Taxonomic diagnoses for the class Remipedia, order Nectiopoda (emended due to discovery that the maxilliped is 9-segmented), and for the families Speleonectidae and Godzilliidae are presented and discussed.     

Mating behavior and time budget of an androdioecious crustacean,Eulimnadia texana (Crustacea: Conchostraca)

The clam shrimp,Eulimnadia texana (Crustacea, Conchostraca), is found in freshwater ephemeral environments throughtout the United States. Individual clam shrimp of this species are either hermaphroditic or male, a relatively rare mating system for animals known as androdioecy. Comparison of sex ratios between four neighboring populations ofE. texana in Southern New Mexico showed wide variation in the ratio of males to hermaphrodites with males making up as much as 42% of some populations and not occurring at all within others. Since little is known about the behavior of this species, an ethogram and time budget were prepared based on observations of laboratory populations. Males attempt to clasp hermaphrodites prior to mating. Precopulatory mate guarding occurs in this species. Outcrossing generally occurs during mate guarding and after the hermaphrodite molts. Hermaphrodites, however, seem to control the mating process. Successful mating by males never occured if the hermaphrodite struggled with him; hermaphrodite will self in the presence of males.     

Segmental mismatch in crustacean appendages: the naupliar antennal exopod of Artemia (Crustacea, Branchiopoda, Anostraca)

Based on traditional techniques and confocal laser scanning microscopy for external morphology, and immunohistochemistry for the muscular system, we describe here the segmental features of the antennal exopod of Artemia nauplii. Two kinds of serial elements are present, i.e. setae (with cuticular folds at their base) and ringlets (serially arranged sclerites separated by joint-like cuticular folds not extending to form complete rings around the appendage). The two series are usually not in register. The cuticular folds of the setae and of the ringlets are also sites of intermediate insertions of the three exopod muscles: as the two tegumentary structures are discordant in periodicity, this is also mirrored in the pattern of muscle insertions on the two sides of the appendage. Similar cases of segmental mismatch are known for the trunk of several arthropods, but segmental mismatch along the appendages has received very little attention. The occurrence of segmental mismatch in the naupliar appendages of both extant and fossil crustaceans is reviewed and it is suggested here to be a primitive feature of the exopods of both second antennae and mandibles. Problems in the interpretation of morphological evidence are discussed, also in relation to development and evolution of segmentation of naupliar appendages.     

Caprellids (Crustacea: Amphipoda) from Papua New Guinea,with the description of a new species

This is the first study of caprellid amphipods from the coast of Papua New Guinea. Several collections from Madang Lagoon (north) and Bootless Bay (south) have been studied. Seven species in seven genera are recorded, of which Pseudoproto papua sp. nov. is described as new to science. The genus Pseudoproto Mayer, 1903 has consisted, so far, of only one species, Pseudoproto fallax Mayer, 1903. Although only a single male has been found of Pseudoproto papua sp. nov., differences in antennae, mouthparts, gnathopod 2 and pereopods 3 and 4 have revealed that it represents a new species of Pseudoproto. Lateral view figures of all species, together with a key to species level for the Caprellidea from Papua New Guinea are also included. Communicated by H.-D. Franke     

Doxomysis algoaensis, a new mysid species (Crustacea: Mysidacea) from Algoa Bay (South Africa)

Doxomysis algoaensis sp.nov. is described from Algoa Bay, South Africa where it is common in nearshore marine waters just beyond the breaker line. D. algoaensis sp.nov. is morphologically similar to D. australiensis, but can readily be distinguished by the shape and armature of the telson and the length of the exopod of the fourth male pleopod. The apical cleft is one fifth the telson length in the former species and one third the length in D. australiensis. The telson apex on each side of the cleft is also armed with five and four stout spines in the two species, respectively. In D. australiensis, the exopod of the fourth male pleopod is almost three times the length of the endopod; in D. algoaensis sp.nov., the exopod is only slightly longer than the endopod. Other distinctive features of D. algoaensis sp.nov. include the maxillary palp, which is only slightly broader than long and the greater number of spines on the endopod of the uropod.     

Long-term changes in the size of the Pomphorhynchus laevis (Acanthocephala) population in the River Avon

Samples of Gammarus pulex and dace, Leuciscus leuciscus , taken from the River Avon, Hampshire, at intervals over a period of 9 years were examined for the presence of the acanthocephalan. Pomphorhynchus laevis. Changes in the incidence and intensity of infection of P. laevis in dace and in G. pulex and in the frequency distribution of P. laevis in dace were used as indicators of the population size of the parasite. Throughout the period of observation, the parasite showed a similar pattern of distribution along the length of the river, although at some sites its abundance varied from year to year. Levels of both incidence and intensity of infection of P. laevis in both hosts at one specific locality remained fairly constant over the 9-year period, and the annual variations fell within the natural range of monthly variation over any 12-month period. The frequency distribution of P. laevis in dace also exhibited a similar pattern throughout the period. It was thus concluded that the population size of P. laevis had not changed to any great extent over the 9 years. The factors responsible for this constancy are discussed in the light of conclusions drawn from earlier work.     

Vemakylindrus cantabricus, a new species of Diastylidae (Crustacea, Cumacea) from the northern Iberian coasts

Eleven species of the genusVemakylindrus Bacescu, 1961 are known at present. A hitherto unknown species is described herein asV. cantabricus, sp. nov., and is compared with the more closely related congeneric species:V. hastatus (Hansen, 1920) andV. stebbingi Day, 1980.Vemakylindrus cantabricus may be distinguished from its congeners by a combination of the following characters: (1) carapace densely covered by hooked denticles and hairs; (2) pseudorostrum shorter than carapace; (3) telson of “Diastylis type” with 5–6 pairs of lateral spines; and (4) external process of basis of third maxilliped with 4 long plumose setae.     

A new freshwater mysid from the Amazon, with a reassessment of Surinamysis Bowman (Crustacea: Mysidacea)

A new species of mysis, Surinamysis robertsonae , is described from the plankton of the Lago Calado, a whitewater lake in the Amazon Basin. This is only the second freshwater mysid to be described from the Amazon. Surinamysis Bowman, 1977, comprising S. robertsonae, S. americana and S. merista , is raised to full generic rank on the grounds of telson morphology (compared to the other species of the Antromysis group) and the flagelliform process of the male antennule.     

Three new genera of nematodes (Strongyloidea: Cloacininae) from the redlegged pademelon,Thylogale stigmatica Gould (Marsupialia: Macropodidae) from eastern Australia

Summary Cassunema exigua n.g., n.sp., Monilonema lacunosa n.g., n.sp. and Foliostoma macropodis n.g., n.sp. are described from the stomach of the redlegged pademelon, Thylogale stigmatica Gould, 1860 (Marsupialia: Macropodidae), from north Queensland, Australia. All three genera belong to the subfamily Cloacininae Stossich, 1899 and to the tribe Macropostrongylinea Lichtenfels, 1980. The genus Cassunema is characterized by a poorly sclerotized buccal capsule with longitudinal ridges formed by the lining of the anterior part of the capsule. The genus Monilonema is characterized by a leaf-crown like flange at the mouth opening, a bulbous cervical collar, and paired dorsal and ventral tubular structures running internally and posteriorly from the collar. The genus Foliostoma is characterized by a leaf crown of tiny elements at the mouth opening, and oesophagus with short narrow anterior part, wide posterior part, bulb narrower than corpus and a heavily sclerotized ring between buccal capsule and oesophagus. A revised definition of the tribe Macropostrongylinea is given together with a key to the genera. ac]19810101     

Spelaeomysis cochinensis,a new mysid (Crustacea: Mysidacea) from a prawn culture field in Cochin,India

Spelaeomysis cochinensis sp. nov., the eighth species of the genus is described from a prawn culture field in Cochin, India. It is characterised by a pair of eye plates with few ommatidia and the fully spiny border of the telson.     

A new species of Cyzicidae (Crustacea: Conchostraca) from Iraq

A new species of Conchostraca, Eocyzicus mesopotamiensis sp. nov., from a small pond in Iraq is described and illustrated. The account includes structural details and means of recognition. Information on the habitat is also given.     

Daphnia (Ctenodaphnia) brooksi (Crustacea: Cladocera), a new species from eastern Utah

A single population of an unusual ctenodaphnid was sampled in a shallow, turbid, temporary pond in eastern Utah in 1965. The animals resemble the African Daphnia (Ctenodaphnia) barbata, but show several morphological differences, and are therefore given the new name Daphnia (Ctenodaphnia) brooksi. Repeated efforts to collect this species since 1965 have failed, suggesting either the species is very rare, or the type population represented an instance of long-distance migration.     

The population biology of the acanthocephalan Pomphorhynchus laevis (Müller) in the River Avon

Regular samples of Gammarus pulex and dace Leuciscus leuciscus and occasional grayling Thymallus thymallus and chub L.cephalus were examined from the River Avon, Hampshire, for the presence of the acanthocephalan Pomphorhynchus leavis . The parasite only occurred in medium sized Gammarus due to lower probability of contact with small gammarids and stunted growth and selective mortality amongst older infected ones. No cycles in incidence or development of the parasite in G.pulex were observed. The parasite infected gammarids and grew in all months, and cystacanths were available throughout the year. Despite seasonal feeding activity and dietary preferences, fish fed on Gammarus and acquired infections in all months. Dispersion of P.laevis within the fish population was related to host feeding behaviour. No evidence of seasonal cycles in incidence or intensity of infection in fish was found, and observed monthly changes in the parasite population were related to changes in size structure of the host sample. In dace and grayling P.laevis grew little and matured only in summer, but in chub it grew and produced acanthors all year. The parasite population in fish appeared to be in a state of dynamic equilibrium and gain and loss of parasites took place throughout the year with the level of infection at any moment being determined primarily by the feeding behaviour of the host. This relationship between host diet, water temperature and parasite population size is discussed, and P.laevis in the R. Avon compared with other localities and other parasites.     

Johnius (Johnius) laevis,a new sciaenid from northern Australia and Papua New Guinea

A new sciaenid,Johnius (Johnius) laevis, is described from northern Australia and Papua New Guinea. Amongst theJohnius (Johnius) species with no mental barbel, ctenoid body scales, and more than 10 lower gill rakers, the new species is distinguished by the combination of the following characters: dorsal soft rays 29–34; scales above the lateral line 5–6, and below 8–10; eye diameter 22.4–30% HL; interorbital width 24.6–29.8% HL; and body scales with weakly developed ctenii.     

Diversity of isopods (Crustacea): new data from the Arctic and Atlantic Oceans

New data on the diversity pattern of isopods (Crustacea) from the northern most part of the North Atlantic and the Arctic Oceans is presented. The pattern of diversity with depth is similar at depths <1000m, but differs considerably below about 1000m. In the Arctic the diversity of isopods (expressed both as numbers of species per sled and expected number of species) increased with increased depth to a maximum at depths of about 320 to 1100m, but then declined towards deeper waters. There was a significant increase in numbers per sled and in the expected number of species with increased depth in the northernmost part of the North Atlantic Ocean. Additionally, changes occurred in the relative composition of the shallow and deep water fauna, with asellote isopods being relatively larger part of the isopod fauna in the Arctic than in the northern most part of the North Atlantic. This indicates major faunistic changes occurring at the Greenland-Iceland-Faeroe Ridge, possibly caused by rapid changes in the temperature. Furthermore, that the low diversity of the Arctic deep-sea is a regional phenomenon, and not a part of a large scale latitudinal pattern in the North Atlantic.