Penis Morphology Research Articles

Cuticle and muscle variation underlying phenotypic plasticity in barnacle feeding leg and penis form

AbstractMany aspects of barnacle body form are known to be developmentally plastic. Perhaps the most striking examples of such plasticity occur in their feeding legs and unusually long penises, the sizes and shapes of which can change dramatically and adaptively with changes in conspecific density and local water flow conditions. However, whether variation in overall appendage form is mirrored by structural responses in cuticle and muscle is not known. In order to determine how structural variation underlies phenotypic plasticity in barnacle appendages, we examined barnacles occurring at low and high population densities from one wave‐protected and one wave‐exposed site. We used histological sectioning and fluorescence microscopy of feeding legs and penises to compare cuticle thickness, muscle thickness, and muscle organization, and artificial penis inflation to compare penis extensibility. We observed striking differences in cuticle thickness, muscle thickness, and muscle organization between sites that differed in water velocity, but we found no clear differences associated with variation in conspecific density. Penis extensibility also did not differ consistently between sites. These results are consistent with an adaptive explanation for much of the remarkable and complex variation in barnacle feeding leg and penis morphology among sites that differ in water velocity.

The genus Pseudobithynia in Lebanon, with a redescription of three species and additional notes on its ecology

New material of Bithyniidae from Lebanon comprised topotypes of Paludina badiella Küster, 1853, Bithynia saulcyi Bourguignat, 1853, and Bithynia hamicensis Pallary, 1939, which are redescribed, and for which, for the first time, penis morphology is depicted. We found that P. amiqensis Glöer & Bößneck, 2007 is conspecific with P. hamicensis (Pallary, 1939) (syn. n.).

The erection mechanism of the ratite penis

AbstractThe erection mechanism of the penis in most vertebrates is blood vascular. A major evolutionary transition occurred in birds, where the erection mechanism changed from blood vascular to lymphatic. Within birds, however, the erection mechanism of the ratite penis has remained unknown. Early work suggested that the erection mechanism in ostrich Struthio camelus was blood vascular while no description existed for the emu Dromaius novaehollandiae or the rhea Rhea americana. Because the penis in all other described birds has a lymphatic erection mechanism, clarifying that the erection mechanism of ratites is of great importance to understanding one of the major evolutionary transitions of penis morphology within amniotes. Here, we show that the erection mechanism of ratites is lymphatic, confirming that the evolutionary transition to lymphatic erection occurred in the last common ancestor of Aves.

The genus <i>Daphniola</i> Radoman, 1973 (Caenogastropoda: Hydrobiidae) in the Peloponnese, Greece

A valvatiform hydrobiid gastropod, found in a spring at Dhiaselo, W of Sparta, N. Taigetos Mts., Peloponnese, Greece, was identified as Horatia hadei Gittenberger, 1982. Its protoconch sculpture, female reproductive organs and penis morphology are characteristic of Daphniola Radoman, 1973. Maximum likelihood phylogenetic analysis based on COI (cytochrome oxidase subunit I) fragments of mtDNA proved that the species is congeneric with D. exigua (A. Schmidt, 1856) and D. louisi Falniowski et Szarowska, 2000, and thus belongs to the genus Daphniola, and that D. hadei, D. exigua and D. louisi are species-level distinct taxa.

<i>Pseudamnicola exilis</i> (Frauenfeld, 1863) in southern Greece: a remnant of a flock of species (Rissooidea: Hydrobiidae)?

The morphology of shell, penis, and female reproductive organs was studied in five populations of Pseudamnicola exilis (Frauenfeld) from southern Peloponnese and Kithira Island (Greece). No interpopulation differences were found in any of the characters. Thirty eight sequences of mitochondrial cytochrome oxidase subunit I (COI) and nuclear ribosomal 18S RNA genes were analysed. In COI 19 haplotypes, high haplotypy diversity, low nucleotide diversity in each population, and restricted gene flow between populations were found. NCA indicated allopatric fragmentation for all populations, and long-distance colonisation and/or past fragmentation for populations 4 and 5. Mismatch distribution in the most polymorphic population 4 reflected a bottleneck followed by population growth. The values of K2P interpopulation distances, though relatively low, pointed to congeneric distinct species within the Rissooidea. The monophyly of Pseudamnicola/Adrioinsulana clade was confirmed. Most probably the studied populations of Pseudamnicola were part of a flock of vicariant species little differentiated in morphology and ecology, many of which must have disappeared due to human impact.

Two new species of Manaosbiidae (Opiliones: Laniatores) from Panama, with comments on interspecific variation in penis morphology

Abstract In Central America, the family Manaosbiidae is recorded only from Panama and Costa Rica. Four species occur in this region: Barrona williamsi Goodnight & Goodnight 1942, Bugabitia triacantha Roewer 1915, Poassa limbata Roewer 1943, and Zygopachylus albomarginis Chamberlin 1925. In this paper, we describe Barrona felgenhaueri new species (Cocle Province, Panama) and Bugabitia akini new species (Cocle Province, Panama) and report a new record for B. williamsi (Cocle Province, Panama). We used SEM to examine the penis morphology of Barrona Goodnight & Goodnight 1942 and the Caribbean species Cranellus montgomeryi Goodnight & Goodnight 1947 and Rhopalocranaus albilineatus Roewer 1932. We compared genital morphology of these species with published descriptions for Manaosbiidae from South America. With respect to genital morphology, we found that the most variable characters were the number and relative sizes of the setae that occur on the lateral margins of the ventral plate. Other features that exhib...

"<i>Hauffenia</i>" Pollonera, 1898 (Caenogastropoda: Hydrobiidae) in Slovakia: a preliminary report

We studied the shell and penis morphology, and cytochrome oxidase subunit I (COI) gene sequences, in minute, valvatiform hydrobiid gastropods from Slovensky Kras, Slovakia. The morphology confirmed the assignment of the studied snails to the genus Hauffenia, while in the molecular tree they were placed within the Hydrobiidae, and not close to Hauffenia. The results indicate that the Slovak valvatiform hydrobiids are two taxa which presumably represent two genera: Hauffenia Pollonera, 1898 and Lobaumia Haase, 1993. More molecular data on the Austrian and Hungarian taxa are needed.

New familial assignment for two harvestmen species of the infraorder Grassatores (Arachnida: Opiliones: Laniatores)

Incorporating masculine genitalic characters into Opiliones taxonomy has produced important revisions in the systematics of this group of arachnids. Currently, the inclusion of penis morphology in the description of any taxon of Phalangida (harvestmen with penis: Eupnoi + Dyspnoi + Laniatores, as used in Pinto-da-Rocha et al. 2007) has become an almost “mandatory” standard (e.g. Acosta et al. 2007), and opilionologists have been working to establish the masculine genital pattern for each family (e.g., Martens 1986; subchapters in Pinto-da-Rocha & Giribet 2007). Still, in the infraorder Grassatores the diversity in penis morphology is enormous and much structure and functionality remains poorly understood. Unfortunately, for many of the described Grassatores, the genitalia are entirely unknown, and this constitutes an important impediment to reliable familial assignation (e.g., in Kury 2003, 41 genera were considered as incertae sedis). This problem is quite relevant to “phalangodid-like” genera, considering their rather homogeneous external appearance but highly diverse genitalia (Martens 1988). One of the most illustrative examples is the subfamily Tricommatinae Roewer, 1912, that has been originally described under Phalangodidae, but which has a male genitalia groundplan matching the Gonyleptoidea, a very distant superfamily (Giribet et al. 2010). Consequently it was raised to a separate family, closer to the Gonyleptidae than to the Phalangodidae (Kury 1992), and finally regarded as a member of Gonyleptidae (Kury 2003).

Anatomia comparada e morfometria de oligoryzomys nigripes e o. flavescens (rodentia, sigmodontinae) no Rio Grande do Sul, Brasil

Oligoryzomys nigripes e O. flavescens são amplamente distribuídos e simpátricos em diversos biomas. Os caracteres diagnósticos para seus reconhecimentos não são claramente estabelecidos. Neste estudo, foram realizadas a descrição e comparação da morfologia externa, anatomia do crânio, dentes, esqueleto pós crânio, morfologia estomacal e peniana. Análises estatísticas foram geradas a partir de dados morfométricos. A amostra consiste de 208 exemplares provenientes de 24 localidades do Brasil. O. nigripes é maior, com pelagem dorsal mais escura e pelagem ventral esbranquiçada e salpicada de preto. Crânio maior e mais robusto que O. flavescens. O. flavescens é menor, com pelagem dorsal levemente mais clara e ventre amarelado. O padrão de circulação cefálica das duas espécies é derivada de segundo tipo. Em O. flavescens são visualizados acidentes proeminentes na escápula e úmero, enquanto O. nigripes demonstrou maiores diferenças localizadas na crista íliaca, orientação do ísquio e acidentes proeminentes na tíbia e fíbula. A morfologia estomacal de ambos os táxons possui padrão Unilocular-hemiglandular. A morfologia do pênis consiste de báculo central tri-digitado. A análise de função discriminante reconhecem claramente a distinção de dois grupos homogêneos representados pelas espécies. Segundo o teste t duas variáveis morfométricas (largura da placa zigomática e largura do primeiro molar superior) não são relevantes (P > 0.05) para a discriminação dos táxons. Dimorfismo sexual baseado na morfometria foi sustentado pelo teste t para O. nigripes. Em O. flavescens esta condição não é estatisticamente verificada.

Spermatophore expulsion in the carrion beetle Silpha perforata (Coleoptera: Silphidae)

Silphinae (Coleoptera: Silphidae) is an abundant decomposer that plays important roles in the ecosystem. However, there is little information about the life history of this taxon. We found sperm displacement behavior in carrion beetle Silpha perforata. Copulating males bit the female's antenna strongly and inserted the penis into the partner's genital organ more than once. We found a white substance on the tip of penis during copulation. We examined whether this white substance is a previous male's spermatophore, which was removed from the mating partner. When females were dissected just after mating, the same substance that often presents on the penis of mating males was found in the bursa copulatrix of females, although the bursa copulatrix of virgin females was empty. Male behavior during copulation with females of different mating history was also observed to confirm that the removal of spermatophores was observed only in copulation with females that have the spermatophores of previous males. Consequently, we estimated that S. perforata males removed spermatophores of previous males from mating partners. In addition, we dissected the males frozen during copulation, and inspected the penis morphology. This observation revealed that the apical part of the penis was usually hidden in the basal part of penis, but expanded and appeared during insertion. This apical part had many spines, which play an important role in sperm displacement and sexual conflict in some species. These results indicate that there is the sperm competition in S. perforata. This is the first report on sperm competition in Silphinae.

A new species of Santinezia (Opiliones: Cranaidae) from Panama

A new species, Santinezia noctiscansor, most similar to members of the S. festae group, is described from central Panama; this species is the only member of the genus that occurs in Central America. Our examinations of adults and nymphs collected from Coclea nd Panama Provinces revealed that males are sexually mature as penultimate nymphs. The subadult strongly resembles the adult with respect to coloration, scutal outline, armature of femora III-IV, and penis morphology, but differs in having fewer tarsomeres on each leg, a smaller body size (scutal length and width), and a much smaller tubercle on the ventral surface of coxa IV. Natural history observations are provided for specimens collected from the field site in CocleP rovince.

The Morphology of the Os Penis in the Adult Mouse

The Morphology of the Os Penis in the Adult Mouse

Effects of crowding and wave exposure on penis morphology of the acorn barnacle, Semibalanus balanoides

Wave action and low population density can strongly reduce the ability of sessile acorn barnacles to find mates and copulate. For Semibalanus balanoides, penis morphology varies with wave exposure and with characteristics of the mating neighborhood. Field experiments were conducted at five intertidal sites on Long Island, New York, USA from July to December 2005 to determine how wave exposure and aggregation structure influence the length, diameter, mass, and number of annulated folds of the penis. Sparsely crowded barnacles had more annulations in the penis and are inferred to have greater ability to stretch. At higher wave exposure, the diameter of the penis was greater, but the mass was not. This study identifies density of crowding as the most important cue that barnacles respond to when perceiving their mating group and details how penis morphology varies in response to wave exposure.

Repeated and time-correlated morphological convergence in cave-dwelling harvestmen (Opiliones, Laniatores) from Montane Western North America.

BackgroundMany cave-dwelling animal species display similar morphologies (troglomorphism) that have evolved convergent within and among lineages under the similar selective pressures imposed by cave habitats. Here we study such ecomorphological evolution in cave-dwelling Sclerobuninae harvestmen (Opiliones) from the western United States, providing general insights into morphological homoplasy, rates of morphological change, and the temporal context of cave evolution.Methodology/Principal FindingsWe gathered DNA sequence data from three independent gene regions, and combined these data with Bayesian hypothesis testing, morphometrics analysis, study of penis morphology, and relaxed molecular clock analyses. Using multivariate morphometric analysis, we find that phylogenetically unrelated taxa have convergently evolved troglomorphism; alternative phylogenetic hypotheses involving less morphological convergence are not supported by Bayesian hypothesis testing. In one instance, this morphology is found in specimens from a high-elevation stony debris habitat, suggesting that troglomorphism can evolve in non-cave habitats. We discovered a strong positive relationship between troglomorphy index and relative divergence time, making it possible to predict taxon age from morphology. Most of our time estimates for the origin of highly-troglomorphic cave forms predate the Pleistocene.Conclusions/SignificanceWhile several regions in the eastern and central United States are well-known hotspots for cave evolution, few modern phylogenetic studies have addressed the evolution of cave-obligate species in the western United States. Our integrative studies reveal the recurrent evolution of troglomorphism in a perhaps unexpected geographic region, at surprisingly deep time depths, and in sometimes surprising habitats. Because some newly discovered troglomorphic populations represent undescribed species, our findings stress the need for further biological exploration, integrative systematic research, and conservation efforts in western US cave habitats.

Key to the Species of Cosmetidae (Arachnida, Opiliones) of Central America, with Notes on Penis Morphology and Sexual Dimorphisms

To facilitate identification of harvestmen of the family Cosmetidae in Central America, we developed dichotomous keys that distinguish the 33 known genera and the 133 described species for this region. Couplets are based upon characters found in the literature and examinations of museum specimens. Important characters include the number of tarsomeres on leg I, armature of the dorsal scutum, free tergites and legs, as well as the coloration and relative length of the body and legs. In addition, we provide a summary of sexually dimorphic features and comment on the potential usefulness of penis morphology and coloration as characters for distinguishing taxa.

Explosive eversion and functional morphology of the duck penis supports sexual conflict in waterfowl genitalia

Coevolution of male and female genitalia in waterfowl has been hypothesized to occur through sexual conflict. This hypothesis raises questions about the functional morphology of the waterfowl penis and the mechanics of copulation in waterfowl, which are poorly understood. We used high-speed video of phallus eversion and histology to describe for the first time the functional morphology of the avian penis. Eversion of the 20 cm muscovy duck penis is explosive, taking an average of 0.36 s, and achieving a maximum velocity of 1.6 m s(-1). The collagen matrix of the penis is very thin and not arranged in an axial-orthogonal array, resulting in a penis that is flexible when erect. To test the hypothesis that female genital novelties make intromission difficult during forced copulations, we investigated penile eversion into glass tubes that presented different mechanical challenges to eversion. Eversion occurred successfully in a straight tube and a counterclockwise spiral tube that matched the chirality of the waterfowl penis, but eversion was significantly less successful into glass tubes with a clockwise spiral or a 135 degrees bend, which mimicked female vaginal geometry. Our results support the hypothesis that duck vaginal complexity functions to exclude the penis during forced copulations, and coevolved with the waterfowl penis via antagonistic sexual conflict.

On the enigmatic Heterolacurbs ovalis Roewer, 1912 (Opiliones, Laniatores, Biantidae)

In the course of conducting a systematic review of the Cuban Stenostygninae (Biantidae), it has been deemed critical to review Heterolacurbs ovalis Roewer, 1912 from Togo. The habitus and the enlarged metatarsus III of males (as shown in Roewer 1912: 185, fig. 42 and 1923: 143, fig. 154) of this species, which is currently placed in the Lacurbsinae, point to a close relationship with the Caribbean Stenostygninae (Pérez-González 2007). The occurrence of taxa with morphological similarities on both sides of the Atlantic Ocean demanded a detailed study of this species, mainly its penis morphology. It needed to be tested whether H. ovalis is in fact a member of an ancestral Gondwanan lineage, or if its morphological similarities with species from the other side of the Atlantic are due to convergence.

Molecular systematics of eastern North American Phalangodidae (Arachnida: Opiliones: Laniatores), demonstrating convergent morphological evolution in caves

The phalangodid harvestmen (Opiliones: Laniatores) fauna of the southeastern United States has remained obscure since original descriptions of many genera and species over 60 years ago. The obscurity of this interesting group is pervasive, with uncertainty regarding basic systematic information such as generic limits, species limits, and geographic distributions. This situation is unfortunate, as the fauna includes several cave-obligate forms of interest from both conservation and evolutionary perspectives, and the group likely exhibits interesting biogeographic patterns because of their low dispersal ability. Here, we use DNA sequence data from two genes to reconstruct phylogenetic relationships of southeastern phalangodid taxa, for a sample of all described genera from the region. Our results demonstrate that the southeastern fauna is likely monophyletic, and is most-closely related to western North American phalangodids with a similar penis morphology. Within the southeastern clade, trends in the evolution of penis morphology correspond broadly to molecular phylogenetic patterns, although penis evolution is overall relatively conservative in the group. Biogeographically, it appears that western taxa in the southeast (i.e., from west of the Appalachian Valley) are early diverging, with later diversification in the montane southern Blue Ridge, and subsequent diversification back towards the west. This W>E>W pattern has been observed in other groups from the southeast. The multiple cave-modified species in the region are genetically divergent and appear phylogenetically isolated; explicit topological hypothesis testing suggests that troglomorphism has evolved convergently in at least three independent lineages. The total number of species in the region remains uncertain-mitochondrial COI data reveal many highly divergent, geographically coherent groups that might represent undescribed species, but these divergent mitochondrial lineages do not always exhibit divergence in either nuclear sequences or penis morphology. Many questions remain, but our studies provide a solid framework for further systematic investigations of this interesting group.

ADAPTIVE PLASTICITY OF THE PENIS IN A SIMULTANEOUS HERMAPHRODITE

Acorn barnacles are important model organisms for the study of sex allocation. They are sessile, nonselfing hermaphrodites that copulate with penises that have been suggested to be phenotypically plastic. On wave-exposed shores, Semibalanus balanoides develop penises with relatively greater diameter whereas in wave-protected sites they are thinner. A reciprocal transplant experiment between wave-exposed and protected sites tested whether these exposure-specific morphologies have adaptive value. Mating success was compared over a range of distances to compare the ability of barnacles to reach mates. Barnacles that grew in the wave-protected site and mated in the wave-protected site fertilized more broods at increasing distances than those transplanted to the wave-exposed site. For barnacles that developed in the wave-exposed site, there was no difference in the ability to fertilize neighbors between sites of differing exposure. This study demonstrates the adaptive value of plasticity in penis morphology. The results suggest a trade-off between development of a penis adapted to wave exposure and the ability to fertilize distant mates. Barnacles in different physical environments are limited by different factors, which may limit numbers of potential mates, constrain optimal sex allocation strategies and alter reproductive behavior.

Independent evolutionary reductions of the phallus in basal birds

Despite a long history of anatomical studies in birds, the genitalia of most avian species remain undescribed. Birds are the only vertebrate taxon with internal fertilization where an intromittent phallus has been lost in most species. Studying the anatomical transitions of the avian phallus in those species where it is still present, allows us to test evolutionary hypotheses of why the phallus was lost in the ancestor of modern birds. As part of an anatomical survey of the evolution of avian phallus morphology, we have examined some avian species whose genitalia have not been described. Previously, there were only two known events of phallus reduction in birds: one transition from intromittent to non‐intromittent in the Galliformes, and a complete loss of phallic structures in the ancestor of Neoaves. Here we report three additional cases of phallus reduction in birds: a transition from intromittent to non‐intromittent phallus in Tinamiformes (Crypturellus, Tinamidae), the presence of a non‐intromittent phallus in Alectura (Megapodidae), and a complete loss of the phallus in Leipoa (Megapodidae). In addition, we report on the unique morphology of the Crypturellus non‐intromittent phallus. These new records of phallus reduction highlight the dynamic nature of phallus evolution in birds. Our findings provide evidence against the hypothesis that the phallus in birds is maintained to insure paternity in taxa with exclusive male parental care, since both groups where we report phallus reduction provide predominately male‐only care.