Coxal Plates Research Articles

Vicmusia duplocoxa, gen. et sp.nov., (Crustacea : Amphipoda : Gammaridea) of the new family Vicmusiidae from Australian upper bathyal waters

Vicmusia duplocoxa, gen, et sp. nov., from a depth of 400 m in the Bass Strait Canyon off south-eastern Australia is described. The species possesses three unique apomorphisms: pereonal and pleonal tergites are divided laterally (one dorsal and two lateral subplates to each tergite); coxal plate 2 is strongly reduced among long plates 1, 3 and 4; mouthparts are produced into a setose forward-pointing funnel. The species cannot readily be placed in any of the currently diagnosed gammaridean superfamilies or families, so the new family Vicmusiidae is erected but for now is left as Gammaridea, incertae sedis.

SCANNING ELECTRON MICROSCOPY OF SURFACE MICROSTRUCTURES OF SOME GAMMARIDEAN AMPHIPOD CRUSTACEANS

The cuticular surface of the head and second coxal plate of 124 species (104 genera) of Amphipoda has been examined by scanning electron microscopy. Most of the species examined possess a variety of microstructures that are presumed to be nonsensory, including numerous pores of different sizes and several types of cuticular projections (microtrichs). The microstructures frequently are distributed over the surface in highly ordered arrangements. The functional and phylogenetic significance of these features is discussed. In recent years some attention has been given to the variety of microstructures present on the surface of the integument of amphipod crustaceans. Among the structures described to date are those that appear, on the basis of their morphological organization and relatively restricted distribution, to be sensory. Thus, Mauchline and Ballantyne (1975) have identified by light microscopy several types of presumed sensilla projecting from the integumental surface of both hyperiid and gammaridean amphipods. The scanning electron microscope (SEM) investigations of Cuadras (1982), Holmquist (1982), Schwedhelm (1984), and Oshel (personal communication) on gammarideans provide more details of the morphology of some of these cuticular projections. In Schwedhelm's report, a sensory role for the microstructure described is substantiated by demonstration of its innervation. In other instances, a sensory function is presumed from similarities between the external appearance of the microstructure in question and that of undoubted sense organs described from other arthropods. However, in addition to these putative sensilla there are several other microstructures in amphipods which occur extremely abundantly over much of the cuticular surface and which display other, morphological, characteristics that do not seem compatible with a sensory function. For example, the external opening of each of the very numerous pore canals of three species of Gammarus bears a peglike projection that is not innervated (Halcrow, 1978); these projections in an unstated species of Gammarus have been identified as sensilla and also as microtrichs by Cuadras (1982). According to Richards (1951), microtrichia are projections from the surface ofthe cuticle which may or may not contain a cytoplasmic filament extending from the underlying epidermis. This purely morphological definition of a microtrich is adopted in the present study without any connotations of a sensory function. Pores through the cuticular surface can be even more abundant than the microtrichs (Duncan, 1985; Halcrow, 1985; Moore and Francis, 1985). Several sizes of pores have been described, but it seems that most are the external openings of pore canals. The distinct morphology and ordered distribution of the microtrichs and pores of Gammarus spp. (Halcrow, 1978) suggested that they might be useful characteristics in the taxonomy of the Amphipoda and, particularly, the Gammaridea, a group in which the natural classification continues to be a source of much controversy (Bousfield, 1978; Bowman and Abele, 1982; Barnard and Karaman, 1983). Duncan (1985) has recently used an investigation of the cuticular microstructures of three species of terrestrial talitrid amphipods to speculate on the evolutionary history of this family.

New Distribution Records for Gammar Us Insensibilis Stock, 1966, in Britain

The amphipod Gammarus insensibilis is recorded from the Black and Mediter ranean seas to the Atlantic coast of Europe, extending in distribution as far north as the English Channel (Stock, 1967). Although usually occurring at depths down to 15 m in sheltered brackish waters, in the Mediterranean it can be found in fully marine conditions. In Britain the species has been previously recorded at only two localities, the Chesil Fleet in Dorset (Spooner, 1947 as G. locusta), and New England Creek on the Thames estuary in Essex (Howes, 1939 as G. locusta). Spooner described specimens from both sites as 'aberrant' forms of G. locusta (Linnaeus, 1758), and lists the following characteristics that the form has in common with typical fully-marine G. locusta: (1) elevated urosomal segments, (2) the deep ventral portion of coxal plate 4, (3) the produced angular corner of the lateral lobe, (4) the lack of long hairs on the basal segments of pereiopods 6 and 7, and (5) the sparsity of hairs on antenna 1. These similarities have undoubtedly led to misidentification of G. insensibilis, especially in sheltered brackish areas where it replaces the fully-marine G. locusta. Spooner (1947) also lists characteristics distinguishing his aberrant G. locusta (= G. insensibilis) from the fully-marine G. locusta', (1) the inner ramus of uropod 3 is relatively short, between 80% and 90% of the length of segment 1 of the outer ramus, (2) setae are unusually dense, (3) spines on the ventral border of epimeral plates 2 and 3 are strong in some specimens, (4) the body size is much reduced, and correlated with this, the number of segments in the accessory flagellum is less than 8, and (5) there is a strong tendency in some males for the setae on antenna 2 to be curled. Spooner also noted morphological differences between his two British stocks of aberrant G. locusta (= G. insensibilis). In the present study G. insensibilis and G. locusta were readily distinguished using the following characteristics (Stock, 1966, 1967; Lincoln, 1979):

Acanthonotozoma Serratum, an Arctic Amphipod New to Britain

The amphipod family Acanthonotozomatidae was represented hitherto in British waters by the generaIphimedia Rathke (includingPanoploea Thompson) andOdius Lilljeborg; Acanthonotozoma Boeck being unrecorded (Lincoln, 1979).Material referable toAcanthonotozoma serratum (O. Fabricuius, 1780) is here reported from the East coast of Scotland. Two specimens (1 juvenile,ca. 7 mm long and 1 immature female, broken in half, estimated length 85 mm) were taken by Dr R. Earll by diving (his sample no. CR2, St. 4/3) from amongst tubes occupied by the amphipodEricthonius rubricornis Stimpson attached to boulders amongst coarse sand, depth 345 m, at Coldingham Bay, St Abbs, Berwickshire, Scotland (55° 53' 30": 2° 5' 36") on 17 August 1982. Dr Earll kindly made over his amphipod material to me for identification.Just (1978) has reviewed the genusAcanthonotozoma and has commented on the variability of both morphology and coloration ofA. serratum from Greenland, Iceland, Spitzbergen, Russian Kara Sea, N. Norway and the Skagerrak. The Scottish material has Norwegian rather than Greenlandic characteristics. Thus the dorsal tooth on peraeonite 5 is lacking, giving the dorsum a 4-dentate appearance. Coxal plate 3 is bluntly tapered distally. Coxal plate 4 is squarish and coxal plate 7 has the posterodistal corner unproduced. The posterodistal projections of the third epimeral plate are short with a wide angle between them. The basal articles of peraeopods 57­ have a square, less sharply produced posterodistal corner.Mouthparts and anterior peraeopoda have been dissected from the right side of the female and mounted on three slides in polyvinyl-lactophenol. No significant differences are apparent in mouthpart morphology compared with fig. 4 in Just (1978).

DESCRIPTION OF COWICHANIA INTERSTITIALIS N. GEN., N. SP., AND PROPOSAL OF COWICHANIINAE N. SUBFAM., WITH REMARKS ON PHYLOGENY AND CLASSIFICATION OF HYDRYPHANTIDAE (ACARI: PARASITENGONA: HYDRYPHANTOIDEA)

AbstractMale and female adults of Cowichania interstitialis n. gen., n. sp. are described, and Cowichaniinae n. subfam. is proposed for members of this genus and species. Adults of the new species are autapomorphic among Hydryphantidae in having an entire, uniformly sclerotized dorsal shield, the dorsoglandularia displaced laterally, the genital field located well posteriorly on the idiosoma, and unique sclerotized plates surrounding the coxal plates laterally and posteriorly, and are unusual in having slightly stalked genital acetabula and sexually dimorphic chaetotaxy on the tibiae of the pedipalps. Provisional remarks on phylogeny and higher classification of Hydryphantidae are also presented.

Taxonomy and Distribution of Edotea (= Tropedotea) lyonsi (Menzies and Kruczynski, 1983) N. Comb. (Crustacea: Isopoda: Idoteidae)

Tropedotea lyonsi Menzies and Kruczynski, 1983, is reported from the waters off Alabama southeastward to Cape Romano, Florida. The monotypic genus Tropedotea was recently erected on the basis of coxal plates of pereonites V to VI1 visible in dorsal view and a reduced number of articles in both antennae. Pereonites V to VI11 are also visible in dorsal view in Edotea Gudrin-Mdndville, 1843, and the number of articles in antenna 1 and 2 of Tropedotea Menzies and Kruczynski, 1983, is the same as in Edotea. Hence Tropedotea lyonsi is assigned to the genus Edotea and Tropedotea is designated a junior synonym of Edotea. A total of 40 individuals of Tropedotea lyonsi Menzies and Kruczynski, 1983, were collected with a box core from 12 stations (Figure 1 ) during the Outer Continental Shelf studies of the Minerals Management Service (formerly the Bureau of Land Management) along the west coast of Florida and in the northern Gulf. The monotypic genus Tropedotea Menzies and Kruczynski, 1983 ,was distinguished from Edotea GuCrin-M6nCville, 1843, by having coxal plates visible in dorsal view, antenna 1 consisting of 4 articles and antenna 2 with 5 articles. The remaining characters listed for the genus (e.g., pleon of 2 partly fused segments, maxilliped ' triarticulate, pereopods 1-7 subsimilar, etc.) are not unique but characteristic of other genera or the family Idoteidae as a whole. Edotea is diagnosed as having coxal plates not visible in dorsal view (Richardson 1905, p. 394, Menzies and Frankenberg 1966, p. 21). Tropedotea lyonsi has coxal plates visible in dorsal view, although they are difficult to distinguish. This character is not unique to the genus Tropedotea and until now has been apparently overlooked in the genus Edotea. Edotea triloba (Say, 1818) (= E. montosa Stimpson, 1853) from the northern Gulf of Mexico, from the coast of Georgia, and from Newport, Rhode Island, have indications of the coxal plates on pereonites V to VI1 in dorsal view, incompletely fused with pereonites V to VII. Under sufficient magnification, the remnants of the articulation may be seen, the imperfect fusion evident in both juveniles and adults. The generic diagnosis of Edotea should be emended to state coxal plates imperfectly fused to pereonites V to VI1 and partly visible in dorsal view. The second distinctive feature given by Menzies and Kruczynski for the genus Tropedotea was the number of antennal articles, 4 in antenna 1 and 5 in antenna 2; however, the basal article of antenna 1 and the minute 6th article on antenna 2 were overlooked in the original description of T. lyonsi. An examination of the paratype has shown the antennae of T. lyonsi to be in agreement with Edotea in the number of articles of both antennae. Dr. T. E. Bowman (U. S. National Museum of Natural History, in litt.) has confirmed our observations on the type-specimen. As noted prevlously, the remaining characters described for the genus Tropedotea are shared by other genera within the family Idoteidae. We consider the bilobed frontal lamina Of the cephalon and the presence Of a pair of bifid Spines on the carpus of each pereopod of T. lyonsi as specific rather than generic characters. For the above reasons we assign Tropedotea lyonsi Menzies and Kruczynski, 1983, to the genus Edotea GuCrin-MCnCville, 1843, and consider Tropedotea Menzies and Kruczynski, 1983, a junior synonym of Edotea. GULF OF MEXICO ~ i g u ~ ~ 1. Distribution of Edotea (= Tropedotea)lyom*h the eastem Gulf of Mexico. Circled star is type locality. Depth contours are 20 and 40 meters. Manuscript received July 1 , 1983;accepted August 4 ,1983.

A functional interpretation of coxal morphology in Epimeria cornigera (Crustacea: Amphipoda: Paramphithoidae)

Coxal plates 1–5 of Epimeria cornigera form a closely interlocking series keyed by the head such that ventral flexion of the peraeon is severely curtailed. The clamp formed by coxae 4 and 5 is interpreted as an adaptation facilitating copulation in a species with feeble gnathopods and non-prehensile antennae. The morphology of the posterior three pairs of peraeopods can also be regarded as an adaptation for gripping the female. Other possible functions (e.g. predator deterrence and feeding grip) of coxal structures are also examined.

A scanning electron microscope study of the praniza larva ofGnathia maxillarisMontagu (Crustacea, Isopoda, Gnathiidae), with special reference to the mouthparts

Summary Praniza larvae of Gnathia maxillaris Montagu (Crustacea, Isopoda, Gnathiidae) were examined by scanning electron microscopy. The body comprises a head, swollen peraeon, pleon and telson. Mouthparts are modified for cutting, spearing, and anchorage to the skin of fishes, from which larvae draw blood. Mandibles, maxillules and maxillipedes have serrated surfaces, whereas paragnaths are strongly pointed and gnathopods are hooked. Maxillae were not seen in SEM preparations. They are small structures which probably play little active part in feeding. Pits, which are possibly sense organs, occur on the head, parts of the peraeon, the coxal plates of peraeopods and pleonal somites. Pectinate scales are found on the inner and lateral surfaces of the peraeopods. The pleon, pleopods, the telson and uropods bear small semilunar scales.

A New Species of Water Mite Parasitizing the Backswimmer Buenoa scimitra

Hydrachna virella (Acari: Hydrachnellae), a new species of water mite that parasitizes backswimmers of the species Buenoa scimitra Bare (Hemiptera: Notonectidae), is described. Adults and nymphs are characterized by a pronounced elongation of the posteromedial portion of the 4th coxae. Larvae are distinguished by the relative sizes of the coxal plates and by the positions and relative sizes of the coxal plate setae.

A new species of Psammonyx (Crustacea, Amphipoda, Lysianassidae) from the Northwestern Atlantic

Psammonyx terranovae n.sp., distinguished from P. nobilis in the lack of ventral setae on the anterior coxal plates, is described and figured in detail. A diagnosis of the genus Psammonyx is presented. Psammonyx terranovae has been found in the intertidal in eastern Newfoundland and in the subtidal, south to the Nova Scotia banks. Its distribution is discussed in relation to its temperature tolerances and its possible past history.

Status of Exosphaeroma inornata Dow and E. media George and Stromberg (Isopoda: Sphaeromatidae) with Ecological Notes

The sphaeromatid isopod Exosphaeroma media George and Stromberg 1968 from San Juan Island, Puget Sound, is synonymized with E. inornata Dow 1958 from California. Differences between the original descriptions of both species are attributed to author errors or variations in the phenotype. Variation in the relative position of the rostrum and clypeus, crenulation of the uropod rami, pleotelson shape, coxal plate suture lines, and body ratio (width/length) are discussed. Exosphaeroma inornata is reported to be a wide-ranging intertidal species which is commonly found in crevices, sand, and associated with various algae. Although the distribution is reported to be from San Diego, Calif., north to San Juan Island, Puget Sound, a large distribution gap exists between Humboldt Bay and Puget Sound. Key words: isopod synonomy, anatomical variations, distribution, habitat

The Amphipod Functional Model and Its Bearing upon Systematics and Phylogeny

The peculiar habitus of Amphipods with lateral compression, deep coxal plates 1‐4, broad bases of peraeopods 5‐7, and enlarged pleura (epimeral plates) of abdominal segments 1‐3 is seen as a functional system closely dependent upon the currents produced by the incessant beating of the pleopods. The derivation and position of branchiae and oostegites is discussed. The morphology of more or less aberrant groups, including the suborders Caprellidea and Ingolfiellidea, and its correlations with the mode of life and the basic functional model is analyzed. The possible bearing of the functional model system upon the position of the Amphipoda among the Peracarida is briefly dealt with.

DEEP-SEA AMPHIPODA FROM THE WESTERN NORTH ATLANTIC OCEAN: I. INGOLFIELLIDEA AND AN UNUSUAL NEW SPECIES IN THE GAMMARIDEAN FAMILY PARDALISCIDAE

Ingolfiella atlantisi n. sp. is described from a depth of 4892–4743 m in. the North American Basin, the first ingolfiellid amphipod known from this basin and only the second known from the deep sea. It is a member of a characteristic deep abyssal group of amphipods. The distribution and ecology of the 13 known species in the genus Ingolfiella are summarized. Present evidence is insufficient to distinguish a relic distribution of the known members of this genus from a cosmopolitan distribution of many species. The description of I. atlantisi illustrates the dangers of early splitting of lit tie-known groups into several genera.The pardaliscid amphipod Eperopeus abyssicola n. sp. is described from several locations at abyssal depths in the range 2500–4977 m. It shows a striking convergence to members of the genus Ingolfiella, especially in general body form but also in partial reduction of the coxal plates and partial reduction of the pleopods. This is the second example of such a convergence in the gammaridean amphipods.

Eine neue Niphargus-Art (Gammaridae, Amphipoda) aus Bulgarien

The author describes a new species, Niphargus toplicensis n. sp., of the spring «Toplitzata» near the village of Mussomischta (district of Goze Delcev). N. toplicensis n. sp. Is closely related to N. aquilex moldacicus Dobreanu, Manolache and Puscariu, 1953, N. smederevanus Karaman, 1950, N. anatolicus Karaman, 1950, N. pancici Karaman, 1929, N. pancici clkanovi Karaman, 1959 but differs for several characters (a greater number of setae on the internal lobe of maxilla I, the coxal plates longer than their width, different armour of the telson and of the uropods I etc.).

Notes on the Bionomics of the Tube Building Amphipod,Leptocheirus PilosusZaddach

A study made of the adaptations to tubicolous life found in the small brackish water Photid Amphipod, Leptocheirus pilosus Zaddach, revealed several interesting points.The presence of cement glands in many amphipods has been recognized by several previous authors. In L. pilosus these glands are found mainly in the upper joints of the first two pairs of peraeopods, opening to the exterior through a common duct in the claw. Unicellular glands are also found all over the body, particularly on the coxal plates.

The Swimming and Burrowing Habits of Some Species of the Amphipod Genus Bathyporeia

The swimming and burrowing habits of four species of the genus Bathyporeia have been examined and shown to be alike, and similar to B. robertsoni as described by Schellenberg.Swimming is effected by the pleopods working in a metachronal rhythm, drawing water along a ventral groove formed by the coxal plates of the second peraeopods and the expanded bases of peraeopods 3, 4 and 5.The main water current enters anteriorly between the second gnathopods and is filtered by a series of feathered bristles borne on the basis of this appendage; a subsidiary current enters between the second and third peraeopods.Burrowing is effected mainly by the sweeping action of the second gnathopods and first two pairs of peraeopods, aided by the first and second uropods as soon as they can obtain a purchase on the sand. The adaptation of these three pairs of appendages to burrowing is explained.

A REVISION OF THE NORTH AMERICAN SPECIES OF EANUS

This genus has been considered synonymous with Ludius Esch. but seems distinct by the following characters: form usually robust and strongly convex; front moderately convex, not margined; prothorax wider than long; elytrai striae moderately impressed at base, very feeble or obsolete elsewhere; prosternal lobe rather short; the prosternal process in lateral aspect very strongly arcuate between the coxae and with the apical portion strongly oblique; the prosternal sutures almost straight; coxal plates narrow, more or less narrowed externally; tarsi filiform, the claws simple. Type Limonius estriatus Lec.

Studies of parajulid diplopods. I. The development of the external sexual structures of Parajulus impressus say(8)

AbstractA description of the gross embryology of the sex apparatus of a common diplopod, the corn millipede. The life‐cycle of this animal involves eleven instars extending over a period of three years.In the male the true first legs are shed at the ninth ecdysis and the large clasping appendages are substituted through the last three instars. In the region of the second body somite the fused coxal plate and the penes are developed at the final molt; the second appendages are reduced at this time. The greatest changes occur in the region of the seventh somite, where the legs are shed about the eighth ecdysis and the gonopods developed through the remaining instars. It is evident that these gonopods arise as a modification of the sternites of the seventh somite.In the female the second legs are reduced to vestiges at the final molt. The structures at the mouth of the oviducts are developed from the surrounding tissues and the modified sternites of the reduced second legs. These changes are in progress as early as the seventh instar, but the greatest changes occur at the final ecdysis.