Pengelompokan Spesies Helicotylenchus (Nematoda: Hoplolaimidae) Berdasarkan Karakter Morfologi

Nematoda genus Helicotylenchus adalah salah satu organisme parasit yang dapat menyebabkan kerusakan pada tanaman dan dapat mengakibatkan penurunan produksi. Untuk genus ini sudah ada kompendium yang mencakup beberapa karakter diagnostik yang dapat dimanfaatkan untuk identifikasi. Akan tetapi, karena tidak ada pengelompokan spesies, maka pemanfaatan itu belum bisa terwujud. Penelitian ini dilakukan untuk melakukan pengelompokan spesies-spesies Helicotylenchus berdasarkan karakter morfologi panjang tubuh, Dorsal Oesophageal Gland Opening (DGO), panjang stilet, jumlah anulus kepala, dan jumlah anulus ekor. Pengelompokan dilakukan dengan memvisualisasi data kisaran setiap karakter menjadi hi-lo-close stock chart dengan menggunakan MS Excel. Hasil pengelompokan dengan karakter panjang tubuh terbentuk enam kelompok, DGO tujuh kelompok, panjang stilet tujuh kelompok, jumlah anulus kepala lima kelompok, dan jumlah anulus ekor lima kelompok. Pengelompokan yang paling jelas adalah berdasarkan karakter panjang tubuh. Pengelompokan ini diharapkan dapat membantu identifikasi nematoda genus Helicotylenchus sehingga kajian mengenai spesies genus ini dapat terfasilitasi.

Intra-specific morphological and morphometric variability of Radopholus similis (Cobb, 1893) Thorne, 1949

All the root inhabiting migratory endoparasitic nematode populations of Radopholus procured from banana crop of Vellayani, Thiruvananthapuram, Kerala were identified as Radopholus similis. Heat killed females were straight to slightly ventrally curved posteriorly. Female’s head was low, rounded, continuous or slightly setoff with the body contour. Females were 500-660 µm long and were comparatively longer than males. Males had button shaped head set off by a constriction; female with three to five lip annuli, four crenate and areolated lateral incisures, stylet 14-18 µm long with rounded knobs, vulva post-equatorial (58%), sometimes with slight protuberant lips, ovary paired and equally developed, oesophageal gland overlapped the intestine dorsally, tail elongate-conoid with narrowly rounded terminus. The stylet length (µm), width of stylet knob (µm), distance of excretory pore from anterior end (µm), distance from head to basal bulb (µm), lateral field structure, shape of stylet knob, head region, position of phasmid, tail shape with its terminus, morphometric values like m%, o% and v% and a, c and c´ ratios of females were stable (CV<12%) features. There is an existence of intra-specific variability in the morphological and morphometric features of R. similis. The main morphological diversity was observed with P% of male and female, b ratio of female and stylet length, distance of DEGO from stylet base, o% and T% of male. All the root inhabiting migratory endoparasitic nematode populations of Radopholus Thorne, 1949 procured from banana of Vellayani, Thiruvananthapuram, Kerala were identified as Radopholus similis (Cobb, 1893) Thorne, 1949. A high degree of intra-specific morphometric variability was observed with regard to the total body length (µm), body width (µm), stylet length (µm), distance of dosrsal oesophageal gland orifice (DEGO) from stylet base (µm), number of lip annuli, lip height (µm), distance from head to basal bulb (µm), distance of anus from anterior end (µm), tail length (µm), anal body width (µm), distance of phasmid from tail terminus (µm), number of lateral lines, width of lateral field (µm), b ratio and P % among females of R. similis. Morphometric features like m%, o% and v% of females of R. similis showed least variability. These can be considered as the stable morphometric characters for discrimination of females of R. similis. Ratios like ‘a’ and ‘c’ of females of R. similis were found moderately variable. The morphometric feature and of male i.e. distance from head to basal bulb (µm) was found least variable; while number of lip annuli and spicule length (µm) were moderately variable.

Nematodes from galls on Myrtaceae. XI. Descriptions of five new species of Fergusobia from Australia

Five new species of Fergusobia are described. Fergusobia janetae Davies n. sp. is characterized by the combination of an arcuate to straight, spindle-shaped parthenogenetic female with a relatively small oesophageal gland, an extensile uterus and a conoid tail, an arcuate infective female with a bluntly rounded tail tip, and a C-shaped male with an arcuate to angular spicule and bursa arising at more than 90% of body length. Fergusobia robustae Davies n. sp. is characterized by the combination of a small, C-shaped parthenogenetic female with a short cylindroid tail with a broadly rounded tip; an arcuate to C-shaped, relatively broad, infective female with a tail tip that is almost hemispherical; and an arcuate male with a strong angular spicule and a bursa arising at 30–40% of body length. Fergusobia pruinosae Davies n. sp. is characterized by the combination of a medium sized, open C-shaped, parthenogenetic female in which the cuticle does not swell upon fixation, with a strongly sclerotised stylet, with a more or less narrowly conoid tail with a bluntly or broadly rounded tip; infective female that is arcuate to J-shaped with a notched tail tip; and open C-shaped males with stout, angular spicules and bursa arising near the secretory/excretory pore. Fergusobia pauciflorae Davies n. sp. is characterized by the combination of a medium sized, arcuate, parthenogenetic female with a small stylet, and a conoid tail with a bluntly rounded tip; a small, open C to J-shaped infective female with a broadly rounded to almost hemispherical tail tip; and straight to arcuate males with stout, angular spicules and bursa at ~70% of body length anterior to the cloaca. Fergusobia obliquae Davies n. sp. has a relatively broad, arcuate, parthenogenetic female having a small but strongly sclerotised stylet, and a short conoid tail with a bluntly rounded tip; an arcuate, infective female with an almost hemispherical tail tip; and C-shaped males with arcuate to angular (not heavily sclerotised) spicules and bursa arising 50–80% of body length anterior to tail. Sequencing of the 18S and 28S rDNA domains for F. janetae n. sp. and of mitochondrial DNA cytochrome oxidase subunit I (mtCOI) for F. pauciflorae n. sp. confirm that they are distinct species.

Convergence with naticids: phenotypic phylogenetic study on some Antarctic littorinoideans, with description of the zerotulid new genusPseudonatica, and its presence in Brazil (Mollusca, Caenogastropoda)

Some Antarctic littorinoideans have a remarkable convergence with Naticoidea in shell and operculum features. Two naticid-like species of that group are studied in their phenotypic features in order to improve their taxonomy and to discuss the meaning of that convergence, as the former are herbivore-detritivore and the latter active predatory organisms. One of the studied species is the littorinidLaevilacunaria antarctica(Martens, 1885). The other belongs to a new genus –Pseudonatica, with the type species also newly described:P. antarctica, the genus is tentatively placed in Zerotulidae. Another Pseudonatica is also described,P. ampullarica, based only on shells collected by Marion-Dufresne French expedition off Brazilian coast, this finding expands the occurrence of zerotulids northwards. Besides the similarities of shell and operculum, other structures of these Antarctic species also show singular similarities with naticoideans, such as the wide foot, the complexity of opercular attachment in pedal opercular pad, the wide oesophageal gland, and the coiled arrangement of the pallial oviduct. The phenotypic characters were coded and inserted in a previous large phylogenetic analysis on Caenogastropoda (Simone, 2011), furnishing a wide basis for discussion on the characters, taxonomic position, evolution and adaptations of these organisms.

Philometroides khalili n. sp., a new philometrid nematode (Philometridae) from the operculum of the cyprinid fish Labeo rosae in Zimbabwe

Summary A new nematode species, Philometroides khalili n. sp. (Philometridae), is described from female specimens recovered from the operculum of the freshwater cyprinid fish Labeo rosae Steindachner (Cyprinidae, Cypriniformes) caught in the Bubi River, Zimbabwe. Based on light and scanning electron microscopical examination, the new species mainly differs from the only other African congeneric species P. africanus Moravec et Van As, 2001 in the body shape (filiform), length of gravid female (56 - 71 mm), in possessing a large oesophageal gland with a conspicuously large cell nucleus and in the shape (transversely oval), size (up to 33 - 36 μm high) and distribution of cuticular bosses. From other congeners it differs by a combination of morphological and biometrical features

Developmental modularity and phenotypic novelty within a biphasic life cycle: morphogenesis of a cone snail venom gland

The venom gland of predatory cone snails ( Conus spp.), which secretes neurotoxic peptides that rapidly immobilize prey, is a proposed key innovation for facilitating the extraordinary feeding behaviour of these gastropod molluscs. Nevertheless, the unusual morphology of this gland has generated controversy about its evolutionary origin and possible homologues in other gastropods. I cultured feeding larvae of Conus lividus and cut serial histological sections through the developing foregut during larval and metamorphic stages to examine the development of the venom gland. Results support the hypothesis of homology between the venom gland and the mid-oesophageal gland of other gastropods. They also suggest that the mid-region of the gastropod foregut, like the anterior region, is divisible into dorsal and ventral developmental modules that have different morphological, functional and ontogenetic fates. In larvae of C. lividus , the ventral module of the middle foregut transformed into the anatomically novel venom gland of the post-metamorphic stage by rapidly pinching-off from the main dorsal channel of the mid-oesophagus, an epithelial remodelling process that may be similar to other cases where epithelial tubes and vesicles arise from a pre-existing epithelial sheet. The developmental remodelling mechanism could have facilitated an abrupt evolutionary transition to the derived morphology of this important gastropod feeding innovation.