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Raymond T Bauer - One of the best experts on this subject based on the ideXlab platform.

  • Synalpheus paraneptunus (Crustacea: Decapoda: Caridea) populations with intersex Gonopores: a sexual enigma among sponge-dwelling snapping shrimps
    Invertebrate Reproduction & Development, 2008
    Co-Authors: E. Töth, Raymond T Bauer
    Abstract:

    Summary Caridean shrimp populations are usually gonochoristic, i.e., composed of separate sexes; however, some carideans are protandric sex changers or simultaneous hermaphrodites. In this contribution we investigated the sexual composition and its determination in two sponge-dwelling Synalpheus species with different degrees of sociality. Because the usual external sexing methods (presence or absence of appendices masculinae in males) can not be used in Synalpheus spp., we sexed individuals by observation of male and female Gonopores using scanning electron microscopy (SEM). We found that populations of two species of the Synalpheus paraneptunus complex consist almost entirely of individuals with both male and female Gonopores (termed herein “intersexes”). Such a high incidence of intersexes has not been previously reported in other decapods. We performed morphological and behavioral observations to test various hypotheses explaining the presence of intersex Gonopores. Whereas protandry and simultaneous ...

  • Gonopore sexing technique allows determination of sex ratios and helper composition in eusocial shrimps
    Marine Biology, 2007
    Co-Authors: Eva Tóth, Raymond T Bauer
    Abstract:

    An evaluation of the social organization and sexual system of eusocial species of Synalpheus has been hindered because it has not been possible to determine the sexual composition of colony helpers (workers). The external sexual characters typically used to sex caridean shrimps are lacking in Synalpheus. We used SEM sexing technique to determine the sexual composition of helpers in colonies of Synalpheus regalis, S. rathbunae, S. chacei, S. rathbunae A (see Morrison et al. Mol Phylogen Evol 30:563–568, 2004), and S. filidigitus. Colonies consisted of both sexes and sex ratios of helpers generally conformed to 50:50 female to male. Females were characterized by Gonopores with U-shaped slits on the coxae of the third pereopods (first walking legs) while males had oval Gonopore openings on the coxae of the fifth pereopods (third or last walking legs). In S. chacei, S. filidigitus, and S. rathbunae A, a few helpers were found that had both male and female Gonopores (intersexes). All three reproductive females (queens) of S. filidigitus examined were intersexes. Sexing of helpers allowed us to test some hypotheses about sexual differences in helper morphology that might indicate task specialization (division of labor). Male helpers were not different from female ones in body size (except in S. regalis: males somewhat larger) and in fighting chela size. The lack of sexual dimorphism in these characters suggests no male–female specialization in colony tasks such as defense. The presence of male and female helpers similar in size suggests that the sexual system of these eusocial species is gonochoristic, although protandry of some sort in S. filidigitus can not be ruled out. The intersexuality observed in a few individuals may be due to developmental anomalies, protandry, or even simultaneous hermaphroditism. Finally, the sexing technique allowed us to establish that new colonizers of unoccupied sponges in S. rathbunae are a single male and female of helper size.

  • spermatophore transfer in the hermit crab clibanarius vittatus crustacea anomura diogenidae
    Journal of Morphology, 2002
    Co-Authors: Gregory S Hess, Raymond T Bauer
    Abstract:

    Although mating has been described in several hermit crab species, the mechanics of spermatophore transfer have not previously been demonstrated. Evidence from pleopod and Gonopore morphology, video observations, and inseminated females indicates that in Clibanarius vittatus the male applies a spermatophoric mass directly onto the female via the Gonopores rather than with modified pleopods 1–2 (gonopods) and/or genital papillae as in many other decapods. The single second pleopod of males of C. vittatus has a simple endopod with no apparent modifications for sperm transfer. There are no genital papillae extending from the male Gonopores. The globular spermatophores are aligned in rows surrounded by a seminal secretion in the male ducts (vasa deferentia that terminate in ejaculatory ducts opening to the exterior via the Gonopores). During copulation, described from time-lapse video recordings, the ventral surface of the last thoracic segment of the male, bearing the Gonopores, was apposed to the ventral cephalothorax of the female. A massive amount of seminal secretion containing spermatophore ribbons, termed here the spermatophoric mass and described for the first time in a hermit crab species, was observed covering the sternites and coxae of pereopods 1–5 of a recently copulated female. It is suggested that during copulation the male emits the contents of the ejaculatory ducts directly onto the female without the aid of gonopods or genital papillae. Although spermatophore transfer is simple in C. vittatus, the presence of modified anterior pleopods or elongate genital papillae (sexual tubes) in other paguroidean species suggests the possibility of a more complex insemination process in these other hermit crabs. J. Morphol. 253:166–175, 2002. © 2002 Wiley-Liss, Inc.

Wang An-tai - One of the best experts on this subject based on the ideXlab platform.

Peter Hovingh - One of the best experts on this subject based on the ideXlab platform.

  • Erpobdella (Dina) parva complex (Annelida: Hirudinea: Arhynchobdellida: Erpobdellidae): additional description of Erpobdella parva, E. dubia, and E. lahontana and taxonomic revision
    Hydrobiologia, 2004
    Co-Authors: Peter Hovingh
    Abstract:

    Erpobdella ( Dina ) parva complex ( E. parva , E. dubia , and E. lahontana) were analyzed by species distribution, pigmentation, size, number and position of the labial eyes, tubercle presence, annulus width, Gonopore position, and male genital atrium shape. I concluded that E. parva and E. dubia are conspecific, with the priority name of E. parva . The Lahontan basin species (E. lahontana) , was found to be distinct by Gonopore position, and now includes two additional basins (Granite Springs and Winnemucca). Endemism occurred in the Relict Dace basin complex (Butte and Steptoe basins) with respect to one form of Gonopore positions. The variation in pigmentation, eye position and number, Gonopore position, and male genital organ shape were highly variable in the Great Basin. Examination of the annular widths did not give any guidance to the taxonomic problem of the genera of this complex. It was noted that the Erpobdella parva complex did have some similarities with Nephelopsis obscura .

  • erpobdella dina parva complex annelida hirudinea arhynchobdellida erpobdellidae additional description of erpobdella parva e dubia and e lahontana and taxonomic revision
    Hydrobiologia, 2004
    Co-Authors: Peter Hovingh
    Abstract:

    Erpobdella (Dina) parva complex (E. parva, E. dubia, and E. lahontana) were analyzed by species distribution, pigmentation, size, number and position of the labial eyes, tubercle presence, annulus width, Gonopore position, and male genital atrium shape. I concluded that E. parva and E. dubia are conspecific, with the priority name of E. parva. The Lahontan basin species (E. lahontana), was found to be distinct by Gonopore position, and now includes two additional basins (Granite Springs and Winnemucca). Endemism occurred in the Relict Dace basin complex (Butte and Steptoe basins) with respect to one form of Gonopore positions. The variation in pigmentation, eye position and number, Gonopore position, and male genital organ shape were highly variable in the Great Basin. Examination of the annular widths did not give any guidance to the taxonomic problem of the genera of this complex. It was noted that the Erpobdella parva complex did have some similarities with Nephelopsis obscura.

Eva Tóth - One of the best experts on this subject based on the ideXlab platform.

  • Gonopore sexing technique allows determination of sex ratios and helper composition in eusocial shrimps
    Marine Biology, 2007
    Co-Authors: Eva Tóth, Raymond T Bauer
    Abstract:

    An evaluation of the social organization and sexual system of eusocial species of Synalpheus has been hindered because it has not been possible to determine the sexual composition of colony helpers (workers). The external sexual characters typically used to sex caridean shrimps are lacking in Synalpheus. We used SEM sexing technique to determine the sexual composition of helpers in colonies of Synalpheus regalis, S. rathbunae, S. chacei, S. rathbunae A (see Morrison et al. Mol Phylogen Evol 30:563–568, 2004), and S. filidigitus. Colonies consisted of both sexes and sex ratios of helpers generally conformed to 50:50 female to male. Females were characterized by Gonopores with U-shaped slits on the coxae of the third pereopods (first walking legs) while males had oval Gonopore openings on the coxae of the fifth pereopods (third or last walking legs). In S. chacei, S. filidigitus, and S. rathbunae A, a few helpers were found that had both male and female Gonopores (intersexes). All three reproductive females (queens) of S. filidigitus examined were intersexes. Sexing of helpers allowed us to test some hypotheses about sexual differences in helper morphology that might indicate task specialization (division of labor). Male helpers were not different from female ones in body size (except in S. regalis: males somewhat larger) and in fighting chela size. The lack of sexual dimorphism in these characters suggests no male–female specialization in colony tasks such as defense. The presence of male and female helpers similar in size suggests that the sexual system of these eusocial species is gonochoristic, although protandry of some sort in S. filidigitus can not be ruled out. The intersexuality observed in a few individuals may be due to developmental anomalies, protandry, or even simultaneous hermaphroditism. Finally, the sexing technique allowed us to establish that new colonizers of unoccupied sponges in S. rathbunae are a single male and female of helper size.

Fernando L Mantelatto - One of the best experts on this subject based on the ideXlab platform.

  • reproductive features of the deep water hermit crab sympagurus dimorphus anomura parapaguridae inhabiting pseudoshells in the sw atlantic ocean
    Journal of Natural History, 2017
    Co-Authors: Laura Schejter, M A Scelzo, Fernando L Mantelatto
    Abstract:

    We herein provide information on reproductive aspects (the Gonopore morphology of both sexes, the size of embryonic eggs and the fecundity) of the hermit crab Sympagurus dimorphus from deep waters ...

  • Male reproductive system of the red brocade hermit crab Dardanus insignis (Diogenidae) and its relationship to other family members
    Zoomorphology, 2014
    Co-Authors: Raquel C. Buranelli, Fernando J. Zara, Fernando L Mantelatto
    Abstract:

    The reproductive system of hermit crabs shows species-specific morphology, which can be used in phylogenetic analysis. Here, we describe the male reproductive system of the hermit crab Dardanus insignis , including morphological and biometric analyses of the spermatophore, the Gonopore, and sperm ultrastructure. The morphological analyses were based on 15 selected specimens and carried out by means of light and electron microscopy. Our results indicate a reproductive system composed of lobular testes attached to a simple straight vas deferens connected to the exterior via ventral Gonopores. The Gonopores are ovoid, surrounded by dense serrulate setae, and covered by a membranous operculum. The spermatophores exhibit a tripartite structure, with an elongate ovoid ampulla, a long narrow stalk, and a proximal foot. The spermatozoal ultrastructure shows three main regions: an ovoid-oblong acrosomal vesicle, a nucleus, and cytoplasm with three armlike extensions. Some of these characteristics can also be found in other species of Diogenidae within the genus Dardanus and in members of Coenobitidae, a closely related family. The available information on spermatophore and spermatozoal structure may indicate a closer similarity between the genus Dardanus and the Coenobitidae, compared with other members of Diogenidae.

  • Reproductive apparatus of the male giant hermit crab Petrochirus diogenes (Anomura, Diogenidae): morphology and phylogenetic implications
    Aquatic Biology, 2012
    Co-Authors: Raquel C. Buranelli, Fernando L Mantelatto
    Abstract:

    We describe the male reproductive apparatus of the giant hermit crab Petrochirus diogenes, with morphological and biometric analyses of the spermatophore, the Gonopore and the ultrastructure of the spermatozoa. Specimens were collected from the southern coast of Sao Paulo, Brazil. Morphological analyses were done using stereoscopic, light, transmission and scanning electron microscopy. The reproductive system of this hermit crab is composed of elon- gate and lobular testes followed by vasa deferentia that connect to the exterior via Gonopores. The Gonopores are ovoid and surrounded by setae, and each Gonopore is composed of a mem- branous operculum that forms a depression constituting the Gonopore opening. The Gonopore constitutes a unique structure among the Diogenidae due to its number of setae. The spermato- phores are tripartite, composed of a sperm-containing ampulla, a peduncle and a proximal foot. The spermatozoon has 3 main regions (acrosomal vesicle, nucleus and cytoplasm). The structure of the spermatophore indicates that this species can be considered an exception within Dio- genidae with regard to spermatophore morphology and can therefore be used for phylogenetic inferences.

  • Spermatophore and Gonopore Morphology of the Southwestern-Atlantic Hermit Crab Pagurus exilis (Benedict, 1892) (Anomura, Paguridae)
    Zoological Studies, 2010
    Co-Authors: M A Scelzo, Marina Zilio Fantucci, Fernando L Mantelatto
    Abstract:

    The form and function of the spermatophore have been used as a complementary tool in studies of the reproductive biology and systematics of hermit crabs. In this context, we describe the spermatophore and Gonopore morphology of Pagurus exilis. The spermatophores were extracted from the distal part of the vas deferens of specimens collected in Argentina and Brazil. The spermatophores were composed of 3 major regions: a main ampulla (with a sperm capsule inside and an accessory ampulla at the base), a stalk, and a pedestal. Each spermatophore had a distinct dorsolateral suture line around the ampulla, where the rupture occurs to release the sperm. The spermatophore total length was 1.5 times the main ampulla length. The main ampulla was oval and slightly flattened. A triangular accessory ampulla extended from the main ampulla base to the pedestal on 1 side, and contained no to several sperm. The stalk is short and flattened, and as wide as the main ampulla. One to 3 spermatophores were found attached to each pedestal, which was almost oblong in shape. The dimensions of the spermatophore and its component parts were directly influenced by the size of the hermit crab. Gonopores of males were covered by long pappose setae, while female Gonopores bore a few short cuspidate setae. Specimens from Brazil and Argentina had the same spermatophore morphology, corroborating the previously observed absence of genetic differences between the both populations. The spermatophore morphology of this species has similarities with the broad general pattern of the Paguridae, being most similar to one of the (at least) 3 patterns of spermatophore morphology described for Pagurus.