Cephalic Plate Research Articles

Phylogenetic analysis of <em>Petaloptoctus</em> (Maldanidae: Polychaeta), with description of a new species from southeastern Brazil

We used morphological data for a phylogenetic analysis of the genus Petaloptoctus (Maldanidae: Polychaeta). We found three most parsimonious phylogenetic trees with length = 37, CI = 0.89 and RI = 0.92. The genus Petaloproctus is monophyletic, and is supported by a strongly arched prostomium, pinnate capillary setae, and an anal cup with a reduced dorsal border. Our proposal for the systematisation of the subgroups of Petaloproctus is (( P. tenuis ( P. terriculus + P. neoborealis )) ( P. ornatus ((( P. cirratus + P. dentatus ) ( P. macrodentatus ( P. borealis ( P. vallejoi n. sp. + P. socialis )))))). We also regard Nicomachinae as a monophyletic group with the following synapomorphies: prostomium short and arched; nuchal grooves short and curved; cephalic plate lost; anal pore opening on margin of anal plate. Monophyly of Micromaldane and Nicomache was also supported in the analysis. Petaloproctus vallejoi n. sp. has 19 setigerous and one asetigerous pre-anal segment. The prostomium is rounded, forming a keel with curved laterals. Nuchal grooves are short and deep, strongly curved outwards. Each neuropodium has one acicular spine on setigers 1-3. The pygidium has a large ventral border, and a reduced dorsal border. The anus is terminal, and close to the margin of the anal plate, surrounded by divergent folds.

The systematic position of Lauroiinae Skrjabin and Schikhobalova, 1951 (Nemata: Heterakoidea: Aspidoderidae), as revealed by the analysis of traits used in its diagnosis.

During our work on biodiversity of parasites of mammals of the Neotropics we collected numerous nematodes assignable to species of the family Aspidoderidae (Nemata: Heterakoidea). These nematodes occur as parasites of the cecum and large intestine of marsupials, rodents and xenarthrans (armadillos) only in the New World. As aspidoderid nematodes have been little studied beyond their alpha taxonomy, it is the purpose of the present paper to apply phylogenetic systematic methods to more completely understand the evolutionary relationships of the included species. Members of the aspidoderid subfamily Lauroiinae have had very little work applied to their systematic relationships and no systematic revisions exist that include all recognized species. Diagnostic characters that define species in this subfamily include plate-like cuticular structures on the anterior end. Herein we define a suite of 52 characters derived from studies of specimens using both light and electron microscopy. Our phylogenetic systematic analysis included the eight known species in the Lauroiinae, seven of the Aspidoderinae and four outgroup taxa. The results indicate that the Lauroiinae is paraphyletic, that the cephalic plates on the anterior end are not synapomorphies for the Lauroiinae, and that structures forming the cordon are present in all species of the family. We propose elimination of the subfamily designations in the family Aspidoderidae and we show the utility of using additional characters in the diagnosis of the family and the genera within this family. The resulting hypothesis should serve as the foundation to understand the historical associations of the nematodes with the mammals they infect. © The Willi Hennig Society 2008.

Redescription and illustrations of the Centipede, Ectonocryptops kraepelini Crabill, 1977 (Scolopendromorpha: Scolopocryptopidae: Ectonocryptopinae)

In 1977, R. E. Crabill, Jr., erected Ectonocryptops for a new Mexican centipede from Colima that he named, E. kraepelini. He placed it in the Cryptopidae, but with 23 pairs of legs and pedal segments, it properly belongs in the Scolopocryptopidae, subfamily Ectonocryptopinae, according to today's taxonomy (Shelley & Mercurio 2005). Crabill did not provide illustrations, and the holotype and only specimen, supposedly at the American Museum of Natural History, New York, USA (AMNH), was subsequently lost. Consequently, the identity of this centipede was uncertain until we (Shelley & Mercurio 2005) proposed Ectonocryptoides quadrimeropus, n. gen., n. sp., for an anatomically similar form from neighboring Jalisco. Discovery of the latter allowed us to interpret characterizations in Crabill's verbal account of Ectonocryptops kraepelini, and separate generic status seemed warranted because of different numbers of podomeres on the caudal legs, four in Ectonocryptoides quadrimeropus and five in Ectonocryptops kraepelini (Crabill 1977). Repeated and extensive searches in the type and general collections at the AMNH failed to reveal the missing holotype as did ones at the National Museum of Natural History, Smithsonian Institution, Washington, DC, where Crabill was a curator when he described Ectonocryptops kraepelini. The holotype was discovered in the AMNH by the second author in 2005; the cephalic plate & antennae, coxosternum & segments 1–7, and segments 19–23 plus the caudal legs had been dissected, cleared, and mounted on a slide, whereas segments 8–18 were in a vial of alcohol. The slide mount was in extremely poor condition with darkened and cracked medium that was filled with air bubbles and meniscuses such that critical parts could not be clearly viewed. We removed the mounted parts from the slide, placed them in alcohol with the rest of the specimen, and redescribe Ectonocryptops kraepelini and provide, for the first time, illustrations of anatomical features. We also provide new accounts of the subfamily, Ectonocryptoides, and Ectonocryptoides quadrimeropus, so that all subfamilial components are treated in a single publication. Asterisks (*) in the account of Ectonocryptops kraepelini denote items taken from Crabill's (1977) description that we could not confirm.

New species of Syphacia (Syphacia) Seurat (Nematoda : Oxyuridae) from Pseudomys species (Rodentia : Muridae) from central Australia

Syphacia (Syphacia) brevicaudata sp. nov. is described from the desert rodents Pseudomys desertor Troughton, 1936 and P. hermannsburgensis (Waite, 1896); Syphacia (Syphacia) pseudomyos sp. nov. is described from P. hermannsburgensis from western Queensland and central Northern Territory, Australia. Syphacia (Syphacia) brevicaudata is distinguished from all other species of Syphacia by having a suite of characters including an oval, dorsally and ventrally constricted cephalic plate, no cervical alae, a relatively short tail and two pairs of post-anal papillae. Syphacia (Syphacia) pseudomyos is distinguished from all other species of Syphacia by having a suite of characters including an oval, dorsally and ventrally constricted cephalic plate, no cervical or lateral alae, one pair of post-anal papillae, a relatively short tail and large eggs. Females of a putative species were distinct due to the lack of a cephalic plate but had other characters consistent with the genus. Two other putative species of Syphacia, females only, also collected from P. hermannsburgensis and having oval dorsally and ventrally constricted cephalic plates, could be distinguished from their congeners by a combination of characters including the presence of cervical alae, Syphacia sp. 2, and a protruding vulva, Syphacia sp. 3. These new species are the first records of oxyurid nematodes from the genus Pseudomys, and from Australian arid-zone rodents.

Evidence for post-natal instability of head scalation in the meadow viper (Vipera ursinii) – patterns and taxonomic implications

AbstractIn Squamates, head meristic characters are commonly used in analyses of intraspecific variability, systematics and phylogeny. Taxonomic significance of head scales is based on the assumption that discrete values of particular scales are set at birth and stable during individual ontogeny. In this paper, we analysed ontogenic changes of head scalation in a population of meadow viper (Vipera ursinii), based on multiple recaptures of marked individuals. Our results show that changes of cephalic scales occur both in immatures and in adults; the frequency of occurrence of change in the sample of re-photographed individuals was 52.2%. Oligomerisation was the most frequent change, found in 39.1% of re-photographed individuals. Changes in shape of cephalic plates as well as polymerisation were recorded in 30.4% of re-photographed individuals. Results of the log-linear analyses indicated no relation either between scale change and sex or between scale change and growth. Although we do not suggest that meristic characters of head scales are completely inadequate for taxonomic use, we point out the need for taking into account the ontogenic trajectories of these characters when analysing intra- and interpopulation variability, in systematics and phylogeny.

A new species of Syphacia (Nematoda: Oxyuridae) from Oligoryzomys nigripes (Rodentia: Cricetidae) in Argentina

The aim of this paper is to describe Syphacia kinsellai n. sp. (Nematoda: Oxyuridae) from the cecum of Oligoryzomys nigripes (Olfers 1818) (Sigmodontinae: Oryzomyini) captured in Misiones Province, Argentina. The new species can be differentiated from other species of the genus principally by the shape of the cephalic plate; distribution of submedian papillae and amphids; development of porous badge; presence of derids in females; absence of cervical and lateral alae; shape and structure of accessory hook of gubernaculum; and distance of excretory pore and vulva from the anterior extremity. Until the present, only two species of Syphacia had been reported from Argentina in sigmodontine rodents, the first one parasitizes an Oryzomyini host and the second one an Akodontini host. This new species is the second record of Syphacia from the tribe Oryzomyini in Argentina; however, we propose that the first record, S. oryzomae, should be treated as a nomen dubium.

A NEW SPECIES OF SYPHACIA (NEMATODA: OXYURIDAE) FROM AKODON AZARAE (RODENTIA: CRICETIDAE) IN ARGENTINA

Eight species of Syphacia (Nematoda: Oxyuridae) have been reported from South America in rodents of the Sigmodontinae, only 1 of which has been recorded in Argentina. Syphacia (Syphacia) carlitosi n. sp. is described from the ceca of Akodon azarae bibianae and Akodon azarae hunteri (Sigmodontinae: Akodontini) captured in 3 provinces in the northeast region of Argentina. The new species is differentiated principally by the shape of the cephalic plate; distribution of submedian papillae and amphids; presence, extent, and shape of cervical alae in females; absence of lateral alae; absence of deirids; spicular and gubernaculum length; shape and structure of accessory hook of gubernaculum; and distance of mamelons, excretory pore, and vulva from the anterior extremity. This is the second record of Syphacia parasitizing rodents of the tribe Akodontini.

Syphacia(Syphacia) Abertoni N. SP. (Nematoda: Oxyuridae) from Zyzomysargurus(Thomas)(Rodentia: Muridae)from Northern Australia

SummarySyphacia (Syphacia) abertoni n. sp. (Nematoda: Oxyuridae) is described from the caecum of Zyzomys argurus (Thomas, 1889) (Rodentia: Muridae) from two locations in northern Australia: Mount Isa, Queensland and Coomalie Creek, Northern Territory. Syphacia abertoni is distinguished from other members of the genus by the presence of cervical alae, an elongated oval cephalic plate, size of eggs, and lengths of spicule and gubernaculum.

Consideraciones taxonómicas de Callistochiton pulchellus (Gray, 1828) (Mollusca, Placophora) en Iquique, norte de Chile

Information is presented on taxonomic traits of Callistochiton pulchellus (Gray, 1828) collected at thirteen sites between Iquique (20°12'S-70°09'W) and Pabellon de Pica (20°54'S-70°08'W) in the north of Chile. Sampling sites were at least one km apart. The species was found at only three of the thirteen sampling sites (23%), and only underneath boulders sunken in sand. A new southern limit for this species was recorded in Chanavayita, 54 km south of Iquique. The most important characteristics of its habitat are presently discussed, as well as the the most relevant morphological differences of this species in comparison with Calloplax vivipara (Plate, 1902) which it closely resembles in form and tegmental ornamentation. C. pulchellus had a greater number of radial lines on the cephalic plate (♠ 12) than C. vivipara (♠ 9). It was also noted that the central plates in the former species were more rectangular than those of the latter species.

Phosphatocopina – ostracode-like sister group of Eucrustacea

The Phosphatocopina were long considered as the oldest, Cambrian, record of ostracode Crustacea. However, our detailed analysis of more than 2,500 specimens from the Upper Cambrian ‘Orsten’ of Sweden reveals that Phosphatocopina are neither Ostracoda nor Eucrustacea. The antenna and mandible of the phosphatocopines investigated consist of a prominent limb stem which carries a two-segmented endopod and multi-annulated exopod. This stem portion is now recognised as the fusion product of the coxa and basipod during ontogeny. Phosphatocopina share features, such as the coxa and basipod on antennae and mandibles, as well as ventral body structures such as the prominent pre-oral labrum and a single post-oral cephalic plate, the sternum (with paragnaths on the mandibular sternal portion), exclusively with the Eucrustacea. As a plesiomorphy, the ontogeny of Phosphatocopina starts with a ‘head larva’ with four pairs of limbs, a larva type found in the ground pattern of the Euarthropoda as well as the Crustacea. In contrast, eucrustacean ontogeny begins with a nauplius with three pairs of limbs, a ‘short-head larva’ or orthonauplius. Again, the post-mandibular limbs of phosphatocopines retain the plesiomorphic limb design of a basipod with a setiferous ‘ proximal endite’, whereas Eucrustacea, including the Ostracoda, have their first post-mandibular limb differentiated into a ‘ mouthpart’, the maxillula. Autapomorphies of Phosphatocopina include the small antennula with few terminal setae, a bivalved shield with interdorsum, and the fused coxa and basipod on antenna and mandible. We therefore consider the Phosphatocopina to be the sister group of the Eucrustacea. The respective phosphatocopine species of the Upper Cambrian of southern Sweden are restricted to a particular time zone and may be useful as stratigraphic markers.

Echiniscus barbarae, a new species of tardigrade from Cuba Island (Tardigrada: Heterotardigrada, Echiniscidae, ‘arctomys group’)

A new heterotardigrade, Echiniscus barbarae sp. nov., is described from a moss sample collected in Cuba. This species belongs to the ‘arctomys group’, which contains many problematic species. The new species differs from the most similar species Echiniscus limai mainly by having cephalic, scapular and terminal dorsal plates not faceted. This paper is the first record of Tardigrada from Cuba.

Gongylonema madeleinensis n. sp. (Nematoda: Spiruroidea), from Mastomys erythroleucus (Rodentia) from a Senegalese Island

A new species of gongylonematid parasites of the rodent Mastomys erythroleucus is described. Gongylonema madeleinensis n. sp. differs from the other species of the genus by the size of its eggs and spicules-gubernaculum complex, the form and distribution of its cuticular scutella, and the absence of a pore on its cephalic plate. After examination of the esophageal content of 270 continental and 29 insular rodents, G. madeleinensis n. sp. seems to be endemic to the island "des Madeleines" near Dakar, Senegal.

Observations on the Morphology, Systematics, and Biogeography of the Genus truttaedacnitis (Nematoda: Cucullanidae)

All species of Truttaedacnitis Petter, 1974, were examined for a phylogenetic analysis. Morphological studies showed that Truttaedacnitis truttae (Fabricius, 1794) from North America possessed a reduced button-shaped or nipple-shaped caudal mucron that is in contrast to the sharp spike-shaped mucron commonly reported in Eurasian specimens. Histological studies showed that the excretory pore in Truttaedacnitis sphaerocephala (Rudolphi, 1809) was situated near the level of the pseudobuccal capsule between the 2 parts of the ventral cephalic ridge. Cucullanus heterodonti Johnston and Mawson, 1943 is transferred to Truttaedacnitis based on the presence of prominent cephalic plates separated by sutures. An hypothesis regarding interrelationships among Truttaedacnitis spp. was developed using phylogenetic systematics. The anterior excretory pore is a synapomorphy supporting the monophyly of Truttaedacnitis clitellarius (Ward and Magath, 1917) and T. sphaerocephala parasitizing sturgeons. The arrangement of cephalic plates indicates that Truttaedacnitis pybusae Anderson, 1992 and T. truttae may form a monophyletic group and further supports the monophyly of T. clitellarius and T. sphaerocephala. Using unordered character states of different cephalic plates produced a cladogram that suggested that species in holarctic/circumboreal families (Acipenseridae, Salmonidae, Petromyzontidae) may be monophyletic. The systematics and biogeography of the various species of Truttaedacnitis and their host specificity indicate that associations in this parasite genus are very ancient and of a relictual nature, determined largely by past continental and oceanic configurations, and a combination of vicariance and dispersal.

Microscopic studies of Procamallanus elatensis, a parasite in siganids, Red Sea fish in Egypt

Camallanidae is a common nematode family found in a variety of Red Sea fish. Procamallanids were found to be specific to Siganus luridus and S. rivulatus which are considered to be commercially important fish. Procamallanus elatensis collected from Siganids in the northern Gulf of Elat were first described by Fusco and Overstreet using light microscopy, This report includes the first SEM description of Camallanid nematodes.The parasites were washed in 7% saline and saved in 7% formalin until brought to Brigham Young University.They were washed with sodium cacodylate buffer (pH. 7.2), fixed in OSO4 for 12 hr, washed in cacodylate buffer, immersed into 2% tannic acid for 8 hr, washed in buffer, fixed again in OSO4 for 2 hr, washed in buffer, dehydrated with critical point drying and coated with gold.Adult worms were long, slender, and reddish in color. At the anterior end the mouth was round and surrounded by the cephalic plate.

Variation and systematics in the colubrid snakes of the genus Hydromorphus

Newly collected material (26 specimens) of the snake genus Hydromorphus substantially extends the known variation in cephalic plates, chin shields, mental groove development, segmental counts and colouration. Variation in head shield seems to be associated with the semi-aquatic habits of these snakes. Variation in chin shields and a tendency for reduction of the mental groove may reflect a shift in diet from large to small prey items. Hydromorphus clarki Dunn, 1942, is placed in the synonymy of Hydromorphus concolor Peters, 1859; Hydromorphus dunni Slevin, 1942, from southwestern Panama is considered a valid species; H. concolor is recorded from Guatemala for the first time and ranges from there southward through Central America to central Panama. The latter species is oviparous.

Marine Arthrotardigrada and Echiniscoidea (Tardigrada, Heterotardigrada) from the Indian Ocean

Abstract Three new species of marine Heterotardigrada, Arthrotardigrada and Echiniscoidea from a sandy shore of the Island of Mauritius, are described. They are two species of Stygarctidae: Parastygarctus renaudae and Stygarctus lambertii, and a species of Echiniscoididae: Anisonyches mauritianus. The evolution of the cephalic plate in P. renaudae during post‐embryonal development is somewhat peculiar. A. mauritianus has an evident medial cirrus and sense organs on the first three pairs of legs but both the clavae and the sense organs on the fourth pair of legs are indistinguishable.

Gongylonema aegypti n. sp. (Nematoda: Thelaziidae) from Egyptian rodents

A new species of spiruroid nematode,Gongylonema aegypti, is described from two rodents,Mus musculus andGerbillus gerbillus, from Egypt.G. aegypti is distinguished from closely related species by the size of the spicules and gubernaculum, the absence of cuticular bosses in males, and the size of the egg. SEM studies suggest that the generic diagnosis ofGongylonema should be amended to include the presence of a dorsal pore on the cephalic plate and the presence around the buccal cavity of three triangular teeth (not lips) and two sclerotized plates or interlabia. ac]19850414

Life-history evidence for sibling species in Axiothella rubrocincta (Polychaeta: Maldanidae)

Individual Axiothella rubrocincta Johnson on the Californian coast live in U-shaped tubes, feed on the surface of the sediment, attain densities of 100 m-2, attain lengths of 140 mm, have maximum oocyte diameters of 220 μm and produce demersal larvae. Individuals from Washington populations live in vertical tubes, feed 10–15 cm below the sediment surface, reach densities of 5000 m-2, attain lengths of 60 mm, have maximum oocyte diameters of 385 μm and brood their young in their tubes to at least the 7-setiger stage. Individuals from California have a scalloped posterior margin of the cephalic plate, while individuals from Washington have entire margins. There are no other consistent morphological differences between populations. The population from Eagle Cove, Washington has individuals similar in size and oocyte diameter to individuals from California, but which maintain vertical tubes. A. rubrocincta represents a sibling species complex.

Spatial aspects of cell interactions involved in the determination of dorsoventral polarity in equally cleaving gastropods and regulative abilities of their embryos, as studied by micromere deletions inLymnaea andPatella

In equally cleaving gastropods, the interactions between micromeres and macromeres involved in the determination of the mesentoblast mother cell (3D) were studied by changing the spatial arrangement of the micromeres by deleting one first quartet micromere or its progeny. A fixed relation was found between the deletion site and the place of origin of 3D; therefore, a fixed relation also exists in the configuration of the three remaining first quartet micromeres and the 3D. These results argue against the possibility that the animal-vegetal interactions do not choose between macromeres, but only permit the expression of a choice already made in another way and at another moment. The results are consistent with a stochastic model in which accidental differences between the macromeres in the number or extent of contacts with first quartet micromeres play a discriminating role during micromere - macromere interactions, that lead to 3D determination.Embryos which lack a given first quartet micromere show a total absence of regulation in the larval head pattern; only the cephalic plates show regulative abilities while forming the adult head structures. Therefore, in later stages new activating and restraining factors seem to play a part in the head development.

Scanning Electron Micrographs of the Head Region of Some Species of Aphelenchoidea (Aphelenchina: Nematoda)

The head regions of eighteen species in eight genera, representing six subfamilies in three families, of the Aphelenchoidea were examined with a scanning electron microscope for characters which might be helpful in the taxonomy of this group. All species have the same basic hexaradiate pattern, with a cephalic plate with two subdorsal, two lateral and two subventral lip sectors. The amphidial apertures are widely spaced and located slightly dorsally on the lateral lip sectors, towards the edge of the cephalic plate. There is a prominent cephalic papilla on the outer margin of each of the other four lip sectors. Many specimens have six small papillae or depressions close to the stomatal aperture and these are the inner labial papillae. A second ring of six raised areas probably represents the lips (sensu stricto) which correspond with the position of the outer labial papillae. Several Aphelenchoides spp. have a lip region surrounded by a deep groove so that the lips are contained within a labial disc. The cephalic plate patterns of Aphelenchus and Paraphelenchus are similar to each other and without a labial disc. Huntaphelenchoides, Cryptaphelenchoides and Seinura have the most prominent lips and lip sectors and the Seinura sp. has additional lateral lobes between the stomatal aperture and lateral lips. All of the species, except one Aphelenchoides, have fine annular striations on the head region behind the cephalic plate.