Revision of diplectanid monogeneans (Monopisthocotylea, Diplectanidae) in sillaginid fishes, with a description of a new species of Monoplectanum

Five species of diplectanids are described or redescribed on the basis of sclerotised parts, from a survey of 26 species of Sillaginidae in the Indo-west Pacific. Diplectanum sillagonum Tripathi is widespread, and is recorded on Sillago sihama from tropical Australia north to Hong Kong and west to India, as well as on S. vincenti (in India) and S. attenuata (Persian Gulf). Diplectanum blairense Gupta & Khanna infects S. sihama and S. indica and is sympatric with D. sillagonum over some of its range (Hong Kong to India and south to Bali). Diplectanum flagritubus Nagibina is synonymised with D. blairense. Diplectanum puriense Tripathi is redescribed from S. chondropus in western Thailand, but was not found on specimens of its type host, Sillaginopsis panijus from the Bay of Bengal. Monoplectanum youngi sp. n. is described from Sillago analis, S. ciliata, S. sihama, S. parvisquamis, S. lutea and S. attenuata and is more widespread than D. sillagonum , extending into subtropical waters in Australia. Monoplectanum australe Young infects S. maculata and S. burrus , and appears to be endemic to Australia. The diagnosis of Monoplectanum , until now monotypic, is emended, the genus is unlikely to contain more new species on sillaginid fishes, and its two species probably share a common ancestor with D. blairense. Parasitological evidence favours a close relationship between Sillaginidae and Sciaenidae.     

Parasite biodiversity in a coral reef fish: twelve species of monogeneans on the gills of the grouper Epinephelus maculatus (Perciformes: Serranidae) off New Caledonia, with a description of eight new species of Pseudorhabdosynochus (Monogenea: Diplectanidae)

Coral reefs are known for their high level of biodiversity, but parasite biodiversity has not been evaluated. Cases such as Epinephelus maculatus, described here, show that the numerical estimation of parasite biodiversity in coral reefs could reach more than ten times the number of fish species; consequently, the extinction of certain fish species from endangered coral reefs would result in the co-extinction of at least ten times the number of parasite species. E. maculatus is a grouper of intermediate size (1-2 kg) and common in the coral reefs of New Caledonia, South Pacific. Based on the examination of more than 800 monogenean specimens, 12 species of monogeneans (ten diplectanids and two ancyrocephalids) were differentiated on the gills. These species of diplectanids have not been found in other epinephelines in the same area and thus are considered as specific to this host. In addition, three species of copepods, and isopod larvae, are present on the gills; E. maculatus thus has a total of 16 species of gill ectoparasites, which can be found together on a single individual fish. Diplectanids include Laticola dae Journo & Justine, 2006, which is the most abundant species representing about 50% of the specimens, and nine species which are rare, each representing 2-7% of the specimens: Diplectanum uitoe n. sp. and eight species of Pseudorhabdosynochus Yamaguti, 1958. D. uitoe, provisionally attributed to Diplectanum Diesing, 1858, is characterised by a small conical penis with internal walls. Pseudorhabdosynochus auitoe n. sp., P. buitoe n. sp., P. cuitoe n. sp., P. duitoe n. sp., P. euitoe n. sp. and P. fuitoe n. sp. are differentiated on the basis of the morphology of the sclerotised vagina, but are very similar in other characteristics; P. guitoe n. sp. is characterised by a quadriloculate organ with very thick walls and a very small sclerotised vagina; and P. huitoe n. sp. is characterised by its sclerotised vagina and by very long ventral and dorsal haptoral bars. Two rare (2-3% of specimens) ancyrocephalids, Haliotrema epinepheli Young, 1969 and Haliotrema sp., are briefly described in relation to the male copulatory organs and haptoral bars; H. epinepheli is apparently a generalist species found in various epinephelines and other fish species. A table of the 50 species of diplectanids (Pseudorhabdosynochus, Laticola Yang et al., 2006, Echinoplectanum Justine & Euzet, 2006 and Diplectanum) from serranids is provided.     

Diplectanids infesting the gills of the barramundi Lates calcarifer (Bloch) (Perciformes: Centropomidae), with the proposal of Laticola n. g. (Monogenoidea: Diplectanidae)

Four species of the Monogenoidea, Laticola lingaoensis n. sp., L. latesi (Tripathi, 1957) n. comb. [previously Pseudorhabdosynochus latesi (Tripathi, 1957) Kritsky & Beverley-Burton, 1986], L. paralatesi (Nagibina, 1976) n. comb. [previously Diplectanum paralatesi Nagibina, 1976] and Diplectanum penangi Liang & Leong, 1991, are reported from the gills of Lates calcarifer (Centropomidae) from the South China Sea (new geographical records for L. latesi and D. penangi). Collections from off Bathurst Island, Northern Territory, Australia, represent a new geographic record for L. paralatesi; Chilka Lake, Orissa, India, is established as the type-locality for L. latesi. Laticola n. g. (Diplectanidae) is proposed for species with a spoon-shaped copulatory organ with two to four concentric incomplete ridges in the base. Laticola lingaoensis, the type-species of Laticola, is described, and L. latesi and L. paralatesi are redescribed based on specimens from the South China Sea. Pseudorhabdosynochus monosquamodiscusi Balasuriya & Leong, 1995 and Pseudorhabdosynochus yangjiangenesis Wu & Li, 2005 are considered junior subjective synonyms of L. latesi and L. paralatesi, respectively.     

A new genus and new species of Sciaenidae from the Gulf of Panama (Perciformes: Sciaenidae)

Paranebris bauchotae, a new genus and species of sciaenid from the Gulf of Panama is described from three specimens (138-212 mm SL). It is distinguished from all other sciaenids by having granulated tooth plates on the jaws and the premaxillary tooth plates that are exposed laterally of the lower jaw when the mouth is closed. The new genus shares the following characters with the New World genus Nebris: a thick fleshy and cartilage gap present between premaxillary bones where the ascending processes form an A-frame arch; gas bladder with a pair of long U-shaped appendages; and a thick, oval-shaped sagitta with deeply grooved caudal section of the sulcus. Paranebris bauchotae is distinct from all Nebris species in having a firmer interorbital skin and scale cover (spongy to the touch in Nebris), a larger eye (6-7 vs. 8-12 times in head length) and large ctenoid scales (vs. small and cycloid in Nebris).     

Diplectanum yamagutii sp.n.(Monogenea, Monopisthocotylea, Diplectanidae), Parasite de Kyphosus cinerascens (Forsskål) à Hawaii

Diplectanum yamagutii sp.n., a gill parasite of Kyphosus cinerascens (Forsskål, 1775) off Hawaii is described from amongst the type-material deposited by Professor S. Yamaguti in the National Parasite Collection of the United States National Museum of Natural History at Beltsville (Maryland, USA). Diplectanum yamagutii sp.n., D. diplobulbus Yamaguti, 1968, D. nenue Yamaguti, 1968, D. spiculare Yamaguti, 1968 and D. kyphosi (Yamaguti, 1968) comb.n. are sympatric parasites of Kyphosus cinerascens off Hawaii. These five species are distinguished by the shape and size of the armature of both the cirrus and the haptoral sclerotised pieces.     

Optimal identification procedure for Diplostomum paracaudum (Iles, 1959) and D. pseudospathaceum Niewiadomska, 1984 metacercariae (Digenea) based on morphological characters

The diagnostic usefulness of the morphological characters of the metacercariae of two similar species of the genus Diplostomum, D. paracaudum and D. pseudospathaceum, is studied. The data are based on 203 specimens of D. paracaudum and of 153 D. pseudospathaceum from fish infected experimentally. The variability of 14 morphometric features and eight indices is analysed. It appears that no single feature or index can provide a classification (discrimination) rule with a sufficiently small percentage of misclassification. In order to increase the discriminant power, a technique based on the bootstrap method is used, which, combined with a stepwise discriminant analysis, leads to the selection of five metric features. A linear discriminant function, L, obtained for selected characters separates the two species better than any single feature. It also allows each specimen to be classified as D. paracaudum if the value of the function L is positive and as D. pseudospathaceum if negative. The accuracy of this procedure is in excess of 90%.     

REVISION OF THE SPOTTED DOLPHINS, STENELLA SPP.

The taxonomy of the spotted dolphins has been confused. Two apparent species exist, one endemic to the Atlantic and the other pantropical. They have sharply different color patterns and non-overlapping vertebral counts. However, the holotype specimens for most of the names that have been applied to the spotted dolphins (including S. attenuata, S. frontalis, S. plagiodon and others) are skulls only, with no information on coloration or number of vertebrae. The two species overlap in all skull characters; geographical variation in both is pronounced. We used a discriminant analysis based on tooth counts and three skull measurements (standardized to skull width) to identify the type specimens to the two species. We used other criteria for assignment of nominal species for which holotype specimens do not exist. We propose that Stenella frontalis (G. Cuv., 1829) be used for the Atlantic endemic species and Stenella attenuata (Gray, 1846) for the pantropical species and here redescribe the species. Proposed common names are Atlantic spotted dolphin and pantropical spotted dolphin. S. frontalis now includes Delphinus froenatus F. Cuv., 1829, D. doris Gray, 1846 and D. plagiodon Cope, 1866. S. attenuata (a nomen conservandum) includes D. velox G. Cuv., 1829, D. pseudodelphis Wiegmann, ≤ 1840, D. brevimanus Wagner, 1846, D. microbrachium Gray, 1850, D. albirostratus Peale, 1848, Steno capensis Gray, 1865, Clymene punctatus Gray, 1866, Steno consimilis Malm, 1871 and Prodelphinus graffmani Lönnberg, 1934. Unidentifiable to either of the two valid species are D. dubius G. Cuv., 1812, D. pernettensis de Blainville, 1817 (suppressed), D. malayanus Lesson, 1826 and D. Rappii Reichenbach, 1845; these must remain incertae sedis.     

A new genus for Diplectanum setosum Nagibina, 1976 (Monogenea: Dipletanidae), a parasite of Psammoperca waigiensis (Cuvier) (Perciformes: Latidae) from Okinawa-jima Island,Japan

Systematic Parasitology - The diplectanid monogenean Diplectanum setosum Nagibina, 1976 is redescribed based on newly collected specimens from Psammoperca waigiensis (Cuvier) (Perciformes: Latidae)...     

Contribution to the taxonomy of the family Campulidae Odhner, 1926 (Digenea) by means of a morphometric multivariate analysis

Digeneans of the family Campulidae occur exclusively in marine mammals, particularly in cetaceans. Their taxonomy is confused, being based on adult morphology only. We used a multivariate discriminant analysis of morphometric data to provide new evidence on the taxonomy of the Campulidae. Measurements of 217 specimens from 21 species of all seven genera of the family were taken. The percentage of specimens correctly assigned into their own species was 96.3%. The first three discriminant functions accounted for most of the variation between the species, which were grouped together in suprageneric groups along the first and the second function. The ordination pattern observed conforms partly with the established taxonomy of the Campulidae. Variation along the first discriminant function can be interpreted as a gradient of the vitelline extension and the maximum width to length ratio. This function separates three groups of species, corresponding to the Hunterotrematinae, Orthosplanchninae and Campulinae-Lecithodesminae. The last two subfamilies are separated along the second axis, the Lecithodesminae having longer bodies and suckers than the Campulinae. This study also provides some evidence at the generic and specific level.     

Diplectanum squamatum n.sp. (Monogenea:Diplectanidae) fro the gills of Cynoscion guatucupa (Sciecidae) in southwest Atlantic waters

Diplectanum squamatum n. sp. is described from the gills of the sciaenid Cynoscion guatucupa collected off Mar del Plata, Argentina. The new species is distinguished from other species of the genus by the morphology of the hamuli and the male copulatory organ, and presence of scales on the haptor and body. This is the first species of Diplectanum to be reported from southwest Atlantic waters and, with the possible exception of D. cayennense Euzet & Durette-Desset, 1974, the only species from the Atlantic coast of South America.     

Diplectanids infesting the gills of the barramundi Lates calcarifer (Bloch) (Perciformes: Centropomidae), with the proposal of Laticola n. g. (Monogenoidea: Diplectanidae)

Four species of the Monogenoidea, Laticola lingaoensis n. sp., L. latesi (Tripathi, 1957) n. comb. [previously Pseudorhabdosynochus latesi (Tripathi, 1957) Kritsky & Beverley-Burton, 1986], L. paralatesi (Nagibina, 1976) n. comb. [previously Diplectanum paralatesi Nagibina, 1976] and Diplectanum penangi Liang & Leong, 1991, are reported from the gills of Lates calcarifer (Centropomidae) from the South China Sea (new geographical records for L. latesi and D. penangi). Collections from off Bathurst Island, Northern Territory, Australia, represent a new geographic record for L. paralatesi; Chilka Lake, Orissa, India, is established as the type-locality for L. latesi. Laticola n. g. (Diplectanidae) is proposed for species with a spoon-shaped copulatory organ with two to four concentric incomplete ridges in the base. Laticola lingaoensis, the type-species of Laticola, is described, and L. latesi and L. paralatesi are redescribed based on specimens from the South China Sea. Pseudorhabdosynochus monosquamodiscusi Balasuriya & Leong, 1995 and Pseudorhabdosynochus yangjiangenesis Wu & Li, 2005 are considered junior subjective synonyms of L. latesi and L. paralatesi, respectively.     

The systematics of Australian Daphnia (Cladocera: Daphniidae). Multivariate morphometrics

Forty nine characters were measured in each of 76 male and 200 female Daphnia including specimens from all eleven taxa described from the genus in Australia, except D. jollyi. Separate multivariate analyses (cluster, principal components and discriminant) of males and females each revealed only five morphological groups in the genus corresponding to the species D. occidentalis, D. lumholtzi, D. cephalata, D. nivalis, and a conglomerate of all other taxa described from the D. carinata complex, D. carinata (sensu lato). Interpretation of the male results was straightforward, but that for females was not because of the occurrence of an environmentally induced seasonal change in morphology (cyclomorphosis) in females. Log transformations of the female data successfully isolated the effects of cyclomorphosis. The seasonal morphs formed two groups which were further differentiated into taxonomic groups.     

Are geometric morphometric analyses replicable? Evaluating landmark measurement error and its impact on extant and fossil Microtus classification

Geometric morphometric analyses are frequently employed to quantify biological shape and shape variation. Despite the popularity of this technique, quantification of measurement error in geometric morphometric datasets and its impact on statistical results is seldom assessed in the literature. Here, we evaluate error on 2D landmark coordinate configurations of the lower first molar of five North American Microtus (vole) species. We acquired data from the same specimens several times to quantify error from four data acquisition sources: specimen presentation, imaging devices, interobserver variation, and intraobserver variation. We then evaluated the impact of those errors on linear discriminant analysis‐based classifications of the five species using recent specimens of known species affinity and fossil specimens of unknown species affinity. Results indicate that data acquisition error can be substantial, sometimes explaining >30% of the total variation among datasets. Comparisons of datasets digitized by different individuals exhibit the greatest discrepancies in landmark precision, and comparison of datasets photographed from different presentation angles yields the greatest discrepancies in species classification results. All error sources impact statistical classification to some extent. For example, no two landmark dataset replicates exhibit the same predicted group memberships of recent or fossil specimens. Our findings emphasize the need to mitigate error as much as possible during geometric morphometric data collection. Though the impact of measurement error on statistical fidelity is likely analysis‐specific, we recommend that all geometric morphometric studies standardize specimen imaging equipment, specimen presentations (if analyses are 2D), and landmark digitizers to reduce error and subsequent analytical misinterpretations.     

几何形态测量学方法在小哺乳动物化石分类鉴定中的应用——4种(鼠平)类化石大样本的个案研究

小哺乳动物化石在晚新生代生物地层学和生物年代学研究中具有重要作用,尤其是筛洗法在古生物调查中得到广泛应用后,通常可以采集到数量可观的标本,使得其地位较大型哺乳动物化石更加彰显.因此,小哺乳动物化石标本的分类鉴定也成了一项十分关键的工作.然而,传统形态学方法在对大量标本进行分类鉴定时,往往容易受主观因素影响而将不稳定的细微性状变异作为依据建立新种,或者忽视一些肉眼难于察觉的形态学差异而将两个甚至多个类群合并到一起,导致基于形态学的化石分类鉴定随意性增加,失去客观性.此外,对于不具鉴定意义的非关键性单个牙齿,很难凭借肉眼或显微镜观察进行区分.针对这些问题,本文选取了安徽繁昌人字洞早更新世早期三种(鼠平)类甘肃模鼠Mimomys gansunicus,郑氏异模鼠Heteromimomys zhengi和繁昌维蓝尼鼠Hllanyia fanchangensis的1284件臼齿并以早上新世内蒙古比例克的比例克模鼠Mimomys bilikeensis的163件臼齿作为参考,采用几何形态测量学方法在各个臼齿咬合面上分别选取了7～14个同源landmark对咬合面的形态特征进行了线性判别分析,建立了针对这4个种的臼齿咬合面形态差异判别函数.分析结果表明,根据这些landmark所提供的形态差异信息,人字洞的1284件臼齿标本中的确存在3个可以明显区分且形态学性状稳定的类群,先前的分类鉴定得到了验证.与之不同地点不同时代的比例克模鼠也可以很好区分.因此,建立在大样本基础上的这4种(鼠平)类臼齿咬合面同源形态特征的判别函数可以用来描述这些种类较为稳定的形态特征差异,并用来作为今后对样本较少的标本进行分类鉴定时的判别依据.因为几何形态测量学的方法不仅可以对二维的离散landmark数据以及重要形态学特征的轮廓线进行分析,甚至还可以扩展至三维空间,所以上述方法对于较为容易获得大样本标本的小哺乳物化石分类鉴定具有普遍意义.     

Otoliths as natural tags in the systematics of salmonids

Synopsis We studied otolith shape in two species of Salmo and two species of Salvelinus to quantify the accuracy of intraspecific, interspecific, and intergeneric identification. Otolith shape is chiefly population and species specific. Between genera, only 3% of the specimens were incorrectly grouped using discriminant analysis.     

Pseudorhabdosynochus argus n. sp. (Monogenea: Diplectanidae) from Cephalopholis argus, P. minutus n. sp. and Diplectanum nanus n. sp. from C. sonnerati and other monogeneans from Cephalopholis spp. (Perciformes: Serranidae) off Australia and New Caledonia

Monogeneans from three species of Cephalopholis, namely C. argus, C. sonnerati and C. boenak, are described from fish caught off New Caledonia, South Pacific, with comparisons with material from off Queensland, Australia. Pseudorhabdosynochus argus n. sp. from C. argus is present off New Caledonia and Australia; it is characterised by its male quadriloculate organ with very elongate cone, and its sclerotised vagina with anterior trumpet, coiled primary canal and distal part with two chambers and an accessory part. C. boenak has no monogeneans off New Caledonia, but off Australia it harbours Pseudorhabdosynochus sp., a new species which is morphologically related to P. argus. P. minutus n. sp. from C. sonnerati is characterised by its minute body and a sclerotised vagina with two spherical chambers. Diplectanum nanus n. sp. from C. sonnerati is characterised by its very small funnel-shaped male copulatory organ and minute body. A new species, Haliotrema sp. from C. sonnerati is characterised by a very elongate tubular penis; it is distinct from H. cromileptis Young, 1968 (redescribed herein from specimens collected from Cromileptes altivelis off New Caledonia). The species described here include the first members of Pseudorhabdosynochus and the first diplectanids described from species of Cephalopholis. There is no evidence for a clade of Pseudorhabdosynochus species specific to members of Cephalopholis, since the species described here share similarities with other species from Epinephelus. However, it is suggested that the gill structure of Cephalopholis spp. imposes selection toward small body sizes for monogeneans.     

Morphometric discrimination among females of sibling species of Aconophorini (Homoptera: Membracidae)

Abstract. Keys to species of auchenorrhynchous Homoptera are often based on male features, leaving no means for identifying females other than association with males. As a possible solution to this problem, we examined the use of linear discriminant functions derived from morphometric data (ten linear measurements among homologous body landmarks) for distinguishing females in two groups of sibling species in the Neotropical treehopper tribe Aconophorini (Membracidae: Membracinae): (1) Calloconophora caliginosa (Walker) and C.pinguis (Fowler); and (2) Guayaquila minuta (Fowler), G.venezuelensis Dietrich, and Central and South American populations of G.pallescens (Stål). Samples of female specimens identified by association with males were used to derive the discriminant functions. Performance of these discriminant functions as evaluated by jackknifing the data was as follows: 98.11% of the specimens in the first group correctly identified using a combination of three measurements, and 94.94% of the specimens in the second group correctly identified using a combination of ten measurements.     

Multivariate analysis of morphological variation among closely related species Bromus japonicus, B. squarrosus and B. arvensis (Poaceae) in comparison with isozyme evidences

Morphological variation and taxonomic continuum of 110 specimens of Bromus arvensis, B. japonicus and B. squarrosus were analysed to assess the morphological variability of these close taxa. The importance of every morphological character was estimated by the GLM procedure. Stepwise discriminant analysis was used in order to find a set of morphological characters that maximises differences among the species. According to this, the most important characters appeared to be the length of anthers, width of lemma and lemma margin angle shape. The most important characters for the determination of Bromus arvensis was the length of anthers and for B. squarrosus width of lemma. According to the UPGMA cluster analysis, canonical discriminant, classificatory discriminant and principal component analyses, all specimens were separated into three moderately distinct groups which corresponded to the three traditional species. The study showed that qualitative characters were the best for the delimitation of the tax a by statistical analyses and demonstrated the incongruity between the pattern of morphological and genetic (allozyme) variation among the three Bromus species.