ABSTRACT Limb morphology across the arthropods is reviewed using external morphological and internal anatomical data from both recent and fossil arthropods. Evolutionary trends in limb structure are identified primarily by reference to the more rigorous of the many existing phylogenetic schemes, but no major new phylogenetic inferences are presented. Tagmosis patterns are not considered, although the origins and patterns of heteronomy within the postantennulary limb series are analysed. The phenomenon of annulation is examined and two basic types of annuli are recognised: terminal and intercalary. The annulation of the apical segment of a limb results in the formation of terminal flagella, and is typical of primarily sensory appendages such as insect and malacostracan antennules and maxillary palps of some hexapods. Intercalary annulation, arising by subdivision of existing subterminal segments, is common, particularly in the tarsal region of arthropodan walking limbs. Differentiating between segments and annuli is discussed and is recognised as a limiting factor in the interpretation of fossils, which usually lack information on intrinsic musculature, and in the construction of groundplans. Rare examples of secondary segmentation, where the criteria for distinguishing between segments and annuli fail, are also highlighted. The basic crown‐group arthropodan limb is identified as tripartite, comprising protopodite, telopodite and exopodite, and the basic segmentation patterns of each of these parts are hypothesised. Possible criteria are discussed that can be used for establishing the boundary between protopodite and telopodite in limbs that are uniramous through loss of the exopodite. The subdivision of the protopodite, which is typical of the postantennulary limbs of mandibulates, is examined. The difficulties resulting from the partial or complete failure of expression of articulations within the mandibulate protopodite and subsequent incorporation of partial proto‐podal segments into the body wall, are also discussed. The development and homology between the various exites, including gills, on the postantennulary limbs of arthropods are considered in some detail, and the question of the possible homology between crustacean gills and insect wings is critically addressed. The hypothesis that there are only two basic limb types in arthropods, antennules and postantennulary limbs, is proposed and its apparent contradiction by the transformation of antennules into walking limbs by homeotic mutation is discussed with respect to the appropriate level of serial homology between these limbs.
A new species of the cyclopinid genus Cyclopicina, C. toyoshioae sp. nov., was collected from the hyperbenthic layer off northern Kyushu Island, Japan; its description is based on two adult female specimens. This is the first record of the genus from the Indo-Pacific region. The new species can be distinguished from its two known congeners in: (1) the relatively short antennules which do not reach the posterior margin of the dorsal cephalothoracic shield; (2) the shape of seminal receptacles; (3) the segmentation and armature of the cephalothoracic appendages; (4) the shape of the basal protrusion between the rami of legs 1–4; (5) the presence of three outer spines on the third exopodal segment of leg 4; and (6) the presence or absence of outer setae on the free exopodal segment of leg 5. The genus Cyclopicina shows a wide but scattered distribution in hyperbenthic layers, from the continental shelves to deep-sea basins, in the northern hemisphere.
Abstract A new species of the rare arietellid genus Scutogerulus is described from deep hyperbenthic waters off Okinawa, southwestern Japan. This is the second species of the genus. Phylogenetically significant characteristics known only on the basis of the type species are confirmed by the discovery of the new congener, in particular: (1) the genital system of the female exhibits the most plesiomorphic condition of any arietellid genus; (2) the well developed setae on the endopodal segments of the maxillae and maxillipeds are modified into ‘shield‐like setae’ similar to the ‘button setae’ in another arietelloidean family, the Augaptilidae; (3) the outer distal spine on the first exopodal segment of leg 1 is absent.
Three new species of copepod crustaceans are described from material collected from anchialine and brackish habitats inand around the village of Walengkabola on the coast of Muna Island, to the southeast of Sulawesi. A new species of cy-clopoid, Paracyclopina sacklerae n. sp., was described from material collected from the tidal inflow entering into the bot-tom of sinkholes a few metres inland from the shoreline. Detailed comparisons are made with Paracyclopina orientalis(Lindberg, 1941), n. comb., a closely related congener here transferred from its original genus Cyclopetta Sars, 1913. Theassignment of Paracyclopina Smirnov, 1935 to the family Cyclopettidae is followed here despite uncertainty over the va-lidity of some of the families created by the break up of the former Cyclopinidae. Two new species of Boholina Fosshagen& Iliffe, 1989 are described, based on material from the same sinkholes and from caves located up to 700m inland fromthe coast and exhibiting further reduced salinity down to 1.8 ppt. One species, B. parapurgata n. sp., is very closely relatedto B. purgata Fosshagen & Iliffe, 1989 from Bohol island in the Philippines, the other B. munaensis n. sp., is very closelyrelated to B. crassicephala Fosshagen & Iliffe, 1989 also from Bohol island, but a number of fine scale differences in the leg 5 of both sexes are recognised in each case. Keys to valid species of both genera are provided.
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