Sperm of Doradidae (Teleostei: Siluriformes)

Spermatic characteristics were studied in 10 species representing several distinct groups within the catfish family Doradidae. Interestingly, different types of spermatogenesis, spermiogenesis and spermatozoa are correlated with intrafamilial groups previously proposed for Doradidae. Semi-cystic spermatogenesis, modified Type III spermiogenesis, and biflagellate sperm appear to be unique within Doradidae to the subfamily Astrodoradinae. Other doradid species have sperm with a single flagellum, cystic spermatogenesis, and spermiogenesis of Type I (Pterodoras granulosus, Rhinodoras dorbignyi), Type I modified (Oxydoras kneri), or Type III (Trachydoras paraguayensis). Doradids have an external mode of fertilization, and share a few spermatic characteristics, such as cystic spermatogenesis, Type I spermiogenesis and uniflagellate sperm, with its sister group Auchenipteridae, a family exhibiting sperm modifications associated with insemination and internal fertilization. Semi-cystic spermatogenesis and biflagellate spermatozoa are also found in Aspredinidae, and corroborate recent proposals that Aspredinidae and Doradoidea (Doradidae + Auchenipteridae) are sister groups and that Astrodoradinae occupies a basal position within Doradidae. The co-occurrence in various catfish families of semi-cystic spermatogenesis and either biflagellate spermatozoa (Aspredinidae, Cetopsidae, Doradidae, Malapturidae, Nematogenyidae) or uniflagellate sperm with two axonemes (Ariidae) reinforces the suggestion that such characteristics are correlated. Semi-cystic spermatogenesis and biflagellate sperm may represent ancestral conditions for Loricarioidei and Siluroidei of Siluriformes as they occur in putatively basal members of each suborder, Nematogenyidae and Cetopsidae, respectively. However, if semi-cystic spermatogenesis and biflagellate sperm are ancestral for Siluriformes, cystic spermatogenesis and uniflagellate sperm have arisen independently in multiple lineages including Diplomystidae, sister group to Siluroidei.     

Occurrence of biflagellate spermatozoa in Cetopsidae, Aspredinidae, and Nematogenyidae (Teleostei: Ostariophysi: Siluriformes)

In the present study spermiogenesis was investigated in Cetopsis coecutiens (Cetopsidae), and Bunocephalus amazonicus (Aspredinidae), while spermatozoa ultrastructure was investigated in C. coecutiens, B. amazonicus, and Nematogenys inermis (Nematogenyidae). Aspredinidae and Cetopsidae share a spermatogenesis of the semicystic type, and a particular type of spermiogenesis process not reported in any fish group. In the three species analyzed, spermatozoa are biflagellate with flagella having the classical axoneme formulae (9 + 2). The analysis of thirteen characters showed the presence of eight characters shared by Cetopsidae and Aspredinidae, and six characters shared by Cetopsidae and Nematogenyidae, which may suggest that these three families may be more related than actually hypothesized, comprising a very primitive siluriform lineage originated after Diplomystidae.     

Comparative sperm ultrastructure in Nemertea

Although the monophyly of Nemertea is strongly supported by unique morphological characters and results of molecular phylogenetic studies, their ingroup relationships are largely unresolved. To contribute solving this problem we studied sperm ultrastructure of 12 nemertean species that belong to different subtaxa representing the commonly recognized major monophyletic groups. The study yielded a set of 26 characters with an unexpected variation among species of the same genus (Tubulanus and Procephalothrix species), whereas other species varied in metric values or only one character state (Ramphogordius). In some species, the sperm nucleus has grooves (Zygonemertes virescens, Amphiporus imparispinosus) that may be twisted and give a spiral shape to the sperm head (Paranemertes peregrina, Emplectonema gracile). To make the characters from sperm ultrastructure accessible for further phylogenetic analyses, they were coded in a character matrix. Published data for eight species turned out to be sufficiently detailed to be included. Comparative evaluation of available information on the sperm ultrastructure suggests that subtaxa of Heteronemertea and Hoplonemertea are supported as monophyletic by sperm morphology. However, the data do not provide information on the existing contradictions regarding the internal relationships of “Palaeonemertea.” Nevertheless, our study provides evidence that sperm ultrastructure yields numerous potentially informative characters that will be included in upcoming phylogenetic analyses. J. Morphol. 2010. © 2010 Wiley‐Liss, Inc.     

Spermatological characters of monozoic tapeworms (Cestoda: Caryophyllidea), including first data on a species from the Indomalayan catfish

The ultrastructure of spermiogenesis and mature spermatozoon in Lytocestus indicus (Cestoda: Lytocestidae) is described; this is the first representative of this group of monozoic, presumably most basal, tapeworms (Eucestoda) from the Indomalayan region to be documented in this manner. Similarly, as in other caryophyllideans, its spermiogenesis involves the formation of a conical differentiation zone with 2 centrioles associated with striated roots and an intercentriolar body. In the course of the process, 1 of the centrioles develops a free flagellum, which fuses with a cytoplasmic protrusion, whereas the other remains oriented in a cytoplasmic bud. Spermiogenesis is also characterized by the presence of electron-dense material in the early stages of spermiogenesis and a slight rotation of the flagellar bud. The mature spermatozoon of L. indicus is a filiform cell tapered at both extremities that lacks mitochondria; its nucleus has parallel disposition to the axoneme and does not reach up to the posterior extremity of the spermatozoon, which is typical for spermatozoa of the type III pattern. The new data confirm that caryophyllideans share the same type of spermiogenesis that is considered to be plesiomorphic in the Eucestoda. The existing information on spermatological ultrastructure of 8 members for 3 of 4 caryophyllidean families from different host groups (cyprinids and catostomids, both Cypriniformes, and mochokids and clariids, both Siluriformes) from 4 zoogeographical regions (Palearctic, Neotropic, Ethiopian, and Indomalayan regions) demonstrates great uniformity in spermiogenesis and sperm ultrastructure, which does not reflect different taxonomic position of the species studied.     

Seasonal ultrastructural modifications of the seminiferous epithelium in twoEulemur species:E. fulvus andE. macaco

A comparative ultrastructural study of the seminiferous epithelium was conducted during the mating and non-mating seasons of twoEulemur species:E. fulvus andE. macaco. The ultrastructure of the junctional complexes of the Sertoli cells, and the modifications in the spermatids during spermiogenesis are reported. Acridine orange staining of the sperm cells of these animals showed that the chromatin compaction was complete in all spermatozoa.     

A new subfamily of Trichomycteridae (Teleostei, Siluriformes), lower loricarioid relationships and a discussion on the impact of additional taxa for phylogenetic analysis

The Copionodontinae is described as a new subfamily of the neotropical catfish family Trichomycteridae. It comprises two new genera and three new species from north-eastern Brazil: Copionodon gen. nov. (including C. pecten sp. nov. and C. orthiocarinatus sp. nov. ) and Glaphyropoma gen nov. (including G. rodriguesi sp. nov. ) The Copionodontinae can be diagnosed externally by the anterior position of the dorsal fin, the presence of a well-developed adipose fin, and the strongly spatulate shape of the jaw teeth. The subfamily is hypothesized as monophyletic on the basis of several synapomorphies in internal and external anatomy. Copionodontines have the plesiomorphic condition of several characters, relative to all other trichomycterids, including the presence of ductus pneumaticus; the possession of separate pterosphenoids, sphenotics and prootics; the presence of the intercalarium; the complete infraorbital latero-sensory canal; the presence of the interhyal; and the wide lateral opening of the swimbladder capsule. Elsewhere within trichomycterids, these primitive traits are found only in Trichogenes. These and other characters support the hypothesis that copionodontines are the plesiomorphic sister group of all other trichomycterids, and that Trichogenes is their next successive sister group. Contrary to the currently accepted hypothesis, the monotypic Nematogenyidae is proposed as the sister group of the Trichomycteridae, and not of all remaining loricarioids. This change is to a major extent induced by the inclusion of copionodontines and Trichogenes in the analysis of lower loricarioid relationships. The present case is given as an example of the impact that undiscovered taxa, fossil or Recent, may have upon hypotheses of phylogenetic relationships.     

Position of enigmatic miniature trichomycterid catfishes inferred from molecular data (Siluriformes)

Trichomycteridae is a well‐corroborated catfish family that comprises about 300 valid species distributed in eight subfamilies. The phyletic status of the Trichomycterinae is uncertain, with different hypothesis regarding the position of the miniaturized Trichomycterus hasemani group. This group comprises four valid species, and neither its monophyly nor its positioning among the Trichomycteridae was tested in a phylogenetic framework. Bayesian Inference and Maximum Likelihood analyses of a molecular data set comprising the mitochondrial genes 12S and 16S and the nuclear genes H3, MYH6 and RAG2 (2983 bp) for 26 taxa highly supported the miniature catfish T. hasemani group as monophyletic and sister to the Tridentinae, consequently recognized as a new genus of this subfamily. Potamoglanis gen. nov. is diagnosed by seven character states: an angle of 35–40° between the main longitudinal axis of the head and the main axis of the autopalatine; thin tubular shape of the second ceratobranchial; presence of six or seven anal‐fin rays; eyes dorsally placed on head; opercular and interopercular odontodes patches not juxtaposed; absence of a distal process on the hyomandibula and presence of a long process on the anterior region of the hyomandibula. Potamoglanis gen. nov is similar to the Tridentinae genera by the presence of a wide cranial fontanelle; presence of a short ventral process in the opercular bone and by the origin of the dorsal fin placed in a vertical through the anal‐fin origin.     

A phylogenetic assessment of the branchiobdellidan family Branchiobdellidae (Annelida,Clitellata) using spermatological and somatic characters

The spermatozoa of six species belonging to the branchiobdellidan family Branchiobdellidae (i.e. Xironogiton victoriensis, Cirrodrilus kawamurai, Ankyrodrilus legaeus, Xironodrilus formosus, Branchiobdella kobayashii, Branchiobdella orientalis) were studied and compared to the other sperma‐tozoa already described in the group. A parsimony analysis was performed on the spermatozoal data of the species examined, as well as on their somatic characters. The results of the two analyses were contrasted and a further parsimony analysis was run on the matrix comprising both sets of characters. The study of sperm ultrastructure confirmed the genera recognized with traditional somatic characters and the monophyly of the branchiobdellidans. Xironodrilus was proved to be the sister species of Ankyrodrilus and its inclusion into the family Branchiobdellidae was supported. Evolutionary hypotheses on intergeneric differences in the family consistent with its biogeography can be suggested by the cladograms: Xironogiton is an early offshoot of branchiobdellidan lineage migrating to North America and probably radiating only in recent times; Branchiobdella kobayashii has a spermatozoon completely different from that of the other species of the genus, thus suggesting a complex story for this widespread taxon with a disjunct distribution.     

An assessment approach for application of spermatic data in phylogenetic analyses: within the genus Moenkhausia Eigenmann, 1903 (Characiformes: Characidae)

Spermiogenesis and sperm ultrastructure from 21 species of Moenkhausia and others related genera are described. To evaluate the phylogenetic signals, 18 unordered characters were utilized in implied weighting analysis through the program TNT 1.1. Four variations of spermiogenesis were found. In the earliest spermatids, the nucleus can be positioned lateral, eccentric, strongly eccentric or nearly medial in relation to the distal centriole. The nuclear rotation can be present or absent. These spermiogenesis processes are related or intermediate to Type I and Type III. Taking into account the degrees of nuclear rotation during the spermiogenesis and other characteristics, distinct forms of spermatozoa are observed among the species analyzed. The phylogenetic analysis yielded a single most parsimonious tree with fit value 2.70000 and the topology obtained founds Moenkhausia as non‐monophyletic. However, some hypothesis of relationships previously proposed viz the clade 20, which contains the type species Moenkhausia xinguensis, is recovered herein. This clade is supported by five synapomorphies, and it allows the supposition that these species constitute a monophyletic group. The whole topology is presented and discussed.     

Congruence between molecular phylogeny and cuticular design in Echiniscoidea (Tardigrada,Heterotardigrada)

Although morphological characters distinguishing echiniscid genera and species are well understood, the phylogenetic relationships of these taxa are not well established. We thus investigated the phylogeny of Echiniscidae, assessed the monophyly of Echiniscus, and explored the value of cuticular ornamentation as a phylogenetic character within Echiniscus. To do this, DNA was extracted from single individuals for multiple Echiniscus species, and 18S and 28S rRNA gene fragments were sequenced. Each specimen was photographed, and published in an open database prior to DNA extraction, to make morphological evidence available for future inquiries. An updated phylogeny of the class Heterotardigrada is provided, and conflict between the obtained molecular trees and the distribution of dorsal plates among echiniscid genera is highlighted. The monophyly of Echiniscus was corroborated by the data, with the recent genus Diploechiniscus inferred as its sister group, and Testechiniscus as the sister group of this assemblage. Three groups that closely correspond to specific types of cuticular design in Echiniscus have been found with a parsimony network constructed with 18S rRNA data. © 2013 The Linnean Society of London     

Monophyly of Euaesthetinae (Coleoptera: Staphylinidae): phylogenetic evidence from adults and larvae,review of austral genera,and new larval descriptions

Abstract We develop a morphological dataset for the rove beetle subfamily Euaesthetinae comprising 167 morphological characters (135 adult and 32 larval) scored from 30 terminal taxa including 25 ingroup terminals (from subfamilies Euaesthetinae and Steninae) and five outgroups. Four maximum parsimony analyses using different sets of terminals and character sets were run to test the monophyly of (1) Euaesthetinae, (2) Steninae, (3) Euaesthetinae + Steninae, (4) euaesthetine tribes Austroesthetini, Alzadaesthetini, Euaesthetini, Fenderiini and Stenaesthetini, and (5) the ten currently known austral endemic genera together. Analyses of adult and larval character sets separately and in combination recovered the monophyly of Euaesthetinae, Steninae, and both subfamilies together, with strong support. Analysis of 13 ingroup terminals for which complete data were available suggests that monophyly of Euaesthetinae is supported by 19 synapomorphies (13 adult, six larval), of Steninae by 23 synapomorphies (14 adult, nine larval), and of both subfamilies together by 24 synapomorphies (21 adult, three larval). Within Euaesthetinae, only the tribe Stenaesthetini was recovered as monophyletic based on adult characters, and in no analyses were the ten austral endemic genera recovered as a monophyletic group. Phylogenetic relationships among euaesthetine genera were weakly supported, although analyses including adult characters supported monophyly of Octavius and Protopristus separately, and of Octavius + Protopristus, Austroesthetus + Chilioesthetus and Edaphus + Euaesthetus. Steninae may include a third genus comprising two undescribed species probably possessing a ‘stick–capture’ method of prey capture, similar to that in Stenus. These two species formed a strongly supported clade recovered as the sister group of Stenus based on adult characters. Diagnoses and a key to adults are provided for the 15 euaesthetine genera currently known from the austral region (Australia, New Zealand, South Africa and southern South America). Euaesthetine larvae previously were known only for Euaesthetus, and we describe the larvae of nine more genera and provide the first larval identification key for genera of Euaesthetinae.     

PHYLOGENY OF CARTERIA (CHLOROPHYCEAE) INFERRED FROM MOLECULAR AND ORGANISMAL DATA1

Comparative ultrastructural data have shown that at least two distinct groups exist within Carteria. Similarly, interpretations of variation in gross morphological features have led to the discovery of morphologically distinct groups within the genus. Partial sequences from the nuclear-encoded small- and large-subunit ribosomal RNA molecules of selected Carteria taxa were studied as a means of 1) testing hypotheses that distinct groups of species exist within the genus and 2) assessing monophyly of the genus. Parsimony analysis of the sequence data suggests that three Carteria species, C. lunzensis, C. crucifera, and C. olivieri, form a monophyletic group that is the basal sister group to all other ingroup flagellate taxa (including species of Chlamydomonas, Haematococcus, Stephanosphaera, Volvox, and Eudorina). Two other Carteria taxa, C. radiosa and Carteria sp. (UTEX isolate LB 762), form a clade that is the sister group to a clade that includes Haematococcus spp., Chlamydomonas spp., and Stephanosphaera. Thus, the sequence data support the interpretations of ultrastructural evidence that described two distinct Carteria lineages. Moreover, the sequence data suggest that these two Carteria groups do not form a monophyletic assemblage. Parsimony analysis of a suite of organismal (morphological, ultra-structural, life history, and biochemical) character data also suggest two distinct lineages among the five Carteria taxa; however, the organismal data are ambiguous regarding monophyly of these Carteria taxa. When the two independent data sets are pooled, monophyly of Carteria is not supported; therefore, the weight of available evidence, both molecular and organismal, fails to support the concept of Carteria as a natural genus.     

Phylogenetic analysis of the family Ariidae (Ostariophysi: Siluriformes), with a hypothesis on the monophyly and relationships of the genera

Ariid monophyly and intrafamilial relationships are investigated based on cladistic analysis of 230 morphological characters. Terminal taxa examined include whenever possible type‐species, or the most morphologically similar species to the type‐species of the nominal genera, and the largest possible number of species, including cleared and stained specimens, available in zoological collections. Previous hypotheses about monophyly of the Ariidae are strongly corroborated by new synapomorphies discovered in the present study. The subfamily Galeichthyinae and the remaining ariids are strongly supported by new morphological characters. The monotypic subfamily Bagreinae is recognized as the sister group to all nongaleichthyin ariids, supported by a large series of exclusive synapomorphies. A new concept of Ariinae is presented: the subfamily is found to be unequivocally monophyletic and includes all ariid genera, except Galeichthys and Bagre. New data supporting the monophyly of the genera included in the Ariinae are introduced and previous hypotheses of monophyly, species composition, morphological definition, and relationships are reviewed and discussed.     

Spermiogenesis and sperm ultrastructure in ten species of Loricariidae (Siluriformes, Teleostei)

The current study describes the ultrastructural characteristics of spermatogenesis, spermiogenesis, and spermatozoa in specimens of siluriform taxa Neoplecostominae, Hypoptopomatinae, Otothyrinae, Loricariinae, and Hypostominae. Our data show that the characteristics of spermatogenesis and spermiogenesis and spermatozoa ultrastructure of Neoplecostominae are more common to Hypoptopomatinae and Otothyrinae than to Loricariinae and Hypostominae. Furthermore, Loricariinae and Hypostominae have more characteristics in common than with any other group of Loricariidae. These data reinforce the phylogenetic hypotheses of relationships among the subfamilies of Loricariidae. Considering the available data in Loricarioidei, Loricariidae presents ultrastructural characteristics of spermatogenesis and spermiogenesis that are also observed in Astroblepidae, its sister group. However, the most of the characteristics of spermatozoa ultrastructure found in Astroblepidae are also observed in Scoloplacidae, the sister group of a clade composed of Astroblepidae and Loricariidae.     

Ultrastructural and immunocytochemical investigation of acoel sperms with 9 + 1 axoneme structure: new sperm characters for unraveling phylogeny in Acoela

Acoel sperm characters proved useful in deciphering acoel taxonomy. The phylogenetic value of sperm characters in closely related sub-groups or in a monophyletic taxon has not yet been assessed. We have investigated sperm ultrastructure in seven members of the monophyletic taxon Childia sensu (Tekle et al. J Zool Sys Evol Res 43(1):72–90, 2005) and in their closest relatives, the Mecynostomidae (four taxa). All members of Childia examined show little variation in their sperm ultrastructure. The common characters of Childia taxa are: 9 + 1 axoneme structure, the presence of six distal cytoplasmic microtubules in the absence of axial or cortical ones, long nucleus and extensive nucleus–flagella overlap. We have identified a new set of cytoplasmic microtubules lying in the centriolar end of the sperm cell, distal microtubules. The origin and phylogenetic significance of this character is discussed. The types and arrangement of cytoplasmic granules could be used as phylogenetic characters at a low taxonomic level. A loose membrane amorphous core type of granule was found to be a synapomorphy for the following clade within the taxon Childia: C. crassum + C. groenlandica + C. vivipara + C. brachyposthium + C. macroposthium. Sausage shaped granules are plesiomorphic among the taxa examined. The rest of the granule characters were found to be homoplasious. Sperm ultrastructural characters have again proven their concordance with molecular phylogeny. The only morphological synapomorphies known for the sister taxa Childia–Mecynostomidae, in the molecular phylogeny, are characters derived from sperm ultrastructure: distal microtubules arranged in two groups of three microtubules each and a 9 + 1 axoneme structure. The spermatozoa of Childia and Mecynostomidae show 9 + 1 axoneme configuration, seemingly similar to the 9 + ‘1’ axoneme pattern of the Platyhelminthes—Trepaxonemata. Using electron-microscope immunocytochemistry, we have demonstrated that, unlike the central cylinder of trepaxonematans, the central cylinder of the 9 + 1 axonemal pattern in acoels is immunoreactive to tubulin and contains a single central microtubule. Therefore, the 9 + 1 patterns in acoels and trepaxonematans are homoplasious.     

Spermatozoa of tapeworms (Platyhelminthes,Eucestoda): advances in ultrastructural and phylogenetic studies

New data on spermiogenesis and the ultrastructure of spermatozoa of ‘true’ tapeworms (Eucestoda) are summarized. Since 2001, more than 50 species belonging to most orders of the Eucestoda have been studied or reinvestigated, particularly members of the Caryophyllidea, Spathebothriidea, Diphyllobothriidea, Bothriocephalidea, Trypanorhyncha, Tetraphyllidea, Proteocephalidea, and Cyclophyllidea. A new classification of spermatozoa of eucestodes into seven basic types is proposed and a key to their identification is given. For the first time, a phylogenetic tree inferred from spermatological characters is provided. New information obtained in the last decade has made it possible to fill numerous gaps in the character data matrix, enabling us to carry out a more reliable analysis of the evolution of ultrastructural characters of sperm and spermiogenesis in eucestodes. The tree is broadly congruent with those based on morphological and molecular data, indicating that convergent evolution of sperm characters in cestodes may not be as common as in other invertebrate taxa. The main gaps in the current knowledge of spermatological characters are mapped and topics for future research are outlined, with special emphasis on those characters that might provide additional information about the evolution of tapeworms and their spermatozoa. Future studies should be focused on representatives of those major groups (families and orders) in which molecular data indicate paraphyly or polyphyly (e.g. ‘Tetraphyllidea’ and Trypanorhyncha) and on those that have a key phylogenetic position among eucestodes (e.g. Diphyllidea, ‘Tetraphyllidea’, Lecanicephalidea, Nippotaeniidea).     

A biflagellate spermatozoon in the African bonytongue Heterotis niloticus (Teleostei,Osteoglossidae)

In this transmission electron microscopy study, we describe the ultrastructure of the spermatozoon of Heterotis niloticus (Osteoglossiformes), which is distinguished by having two flagella. Our investigation also highlights the great diversity of sperm cell structures observed across osteoglossiform families, such as aflagellate (Gymnarchidae, Mormyridae), monoflagellate (Notopteridae, Pantodontidae) and biflagellate spermatozoa. As biflagellate spermatozoa are rare in vertebrates, we also summarize the orders and families known to possess this ultrastructural character, most of which are fishes.     

Evolution of sperm morphology in potamid freshwater crabs (Crustacea: Brachyura: Potamoidea)

We investigated sperm cells and spermatophores of four species of Old World freshwater crabs belonging to three different genera of the subfamily Potaminae (family Potamidae). Characters previously believed to be apomorphic for the potamid subfamily Potamiscinae were also found to occur in the Potaminae. To infer the morphological ancestral character state combination of the Potamidae, ancestral character state analysis of four different sperm traits was performed, based on a 16S rDNA phylogeny of the investigated species. Comparing molecular phylogeny and character state distribution, several cases of convergent evolution could be identified. The densely packed, coenospermic spermatophores and the occurrence of a ‘tongue‐and‐groove’ connection between operculum and acrosomal zones are probably apomorphies for the whole Potamidae. The spermatozoa of Socotrapotamon socotrense show several unique characters. We also analysed the evolution of acrosome size. The sperm cells of the Potamidae and their sister‐group Gecarcinucidae only slightly overlap in acrosome size. Within the investigated species, the ‘East Asia’ subclade (subfamily Potamiscinae) developed significantly larger acrosomes than the subfamily Potaminae. Our results suggest that the use of brachyuran acrosome morphology for phylogenetic inference at the family level is strongly affected by small sample size, and by convergent character evolution. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010.