Penis Sheath Research Articles

The first proven oxychilid land snail endemic to China (Eupulmonata, Gastrodontoidea).

A new and the first proven oxychilid species endemic to China is reported from Sichuan Province. Sinoxychilusgen. nov. is established based on this new species and has diagnostic traits of the sculptured protoconch, partial epiphallus wrapped by developed penis sheath, penial retractor muscle inserting on the top of penial caecum, spinelets on penial pilasters, absence of epiphallic papilla and perivaginal gland present on vagina and proximal bursa copulatrix duct. In light of shell morphology and through geometric morphometric analyses, Zonites scrobiculatus scrobiculatus Gredler and Z. scrobiculatus hupeina Gredler are proposed to be included in the new genus. A phylogenetic inference based on ITS2 gene indicates that the new genus is systematically close to Oxychilus Fitzinger, which is known from the Western Palearctic and the Southwestern Arabian Peninsula, regions that are geographically far from the distribution range of the new genus.

Hidden diversity in waterfall environments: The genus Acrorbis (Gastropoda: Planorbidae) from the Upper-Paraná Atlantic Forest.

High-energy freshwater environments such as rapids and waterfalls in the Upper-Paraná Atlantic Forest are home to highly endemic minute freshwater snails of the genus Acrorbis. Only one species, Acrorbis petricola, is currently included within this genus, whose geographical distribution is restricted to three known populations, one in Brazil and the other two in Argentina. Because of habitat specificity and limited geographical distribution, the species is considered vulnerable in Argentina and endangered in Brazil. In this work, we identify five new populations of A. petricola in southern Upper-Paraná Atlantic Forest, exclusively found on waterfalls from the Misiones Province, Argentina. Based on these populations and on specimens of one of the two historical populations from the Misiones Province, we explored the morphological features of shells and reproductive system of specimens from each location and provide the first molecular data on the species. We used DNA sequences from cytochrome c oxidase subunit I (COI) and 16S-rRNA genes to investigate the molecular diversity, genetic distances and genealogical relationships among populations. We verified the existence of intra- and interpopulation morphological variability, with the greatest variation being found in spire, spiral sculpture, penis sheath, flagella, prostatic diverticula and bursa copulatrix. We found interpopulation genetic diversity, with no intrapopulation variation, and identified six geographically structured genetic lineages with maximum genetic distances of up to 2.3%. Different combinations of morphological characters with the same genetic background within each locality were observed. The finding of new populations genetically differentiated not only broadens the known distribution of the species, but also illustrates that waterfall environments in the Atlantic Forest harbour a hidden diversity of Acrorbis that still remains to be discovered. This scenario suggests a complex evolutionary history that needs to be unveiled and taken into account for future development of conservation strategies in this endemic genus.

Musculature of the penial complex: A new criterion in unravelling the phylogeny of Hygrophila (Gastropoda: Pulmonata).

The taxonomy of freshwater pulmonates (Hygrophila) has been in a fluid state warranting the search for new morphological criteria that may show congruence with molecular phylogenetic data. We examined the muscle arrangement in the penial complex (penis and penis sheath) of most major groups of freshwater pulmonates to explore to which extent the copulatory musculature can serve as a source of phylogenetic information for Hygrophila. The penises of Acroloxus lacustris (Acroloxidae), Radix auricularia (Lymnaeidae), and Physella acuta (Physidae) posses inner and outer layers of circular muscles and an intermediate layer of longitudinal muscles. The inner and outer muscle layers in the penis of Biomphalaria glabrata consist of circular muscles, but this species has two intermediate longitudinal layers separated by a lacunar space, which is crossed by radial and transverse fibers. The muscular wall of the penis of Planorbella duryi is composed of transverse and longitudinal fibers, with circular muscles as the outer layer. In Planorbidae, the penial musculature consists of inner and outer layers of longitudinal muscles and an intermediate layer of radial muscles. The penis sheath shows more variation in muscle patterns: its muscular wall has two layers in A. lacustris, P. acuta, and P. duryi, three layers in R. auricularia and Planorbinae and four layers in B. glabrata. To trace the evolution of the penial musculature, we mapped the muscle characters on a molecular phylogeny constructed from the concatenated 18S and mtCOI data set. The most convincing synapomorphies were found for Planorbinae (inner and outer penis layers of longitudinal muscles, three-layered wall of the penis sheath). A larger clade coinciding with Planorbidae is defined by the presence of radial muscles and two longitudinal layers in the penis. The comparative analysis of the penial musculature appears to be a promising tool in unraveling the phylogeny of Hygrophila.

Physical characteristics of Kosali breed of cattle in its native tract

Kosali, the first breed of cattle from Chhattisgarh, was registered as 36th breed. Characterization is essential to guide decision-making in livestock development and breeding programmes. Hence, a survey was carried out to characterize the Kosali breed of cattle in Central Plain Region of Chhattisgarh state. The coat colour of most animals was red followed by white and black. Mostly muzzles, tail switch, eyelashes, and hooves were black in colour. Body size, hump, dewlap, naval flap, penis sheath flap, udder and teats were small in size. Horns were stumpy, small and slightly inward and ears were horizontal. The estimated average live weight of adult female and male were 168.7±2.82 and 212.5±3.8 kg, respectively. The mean linear measurements of female vs male Kosali cattle were height at wither (99.79±2.76 vs 103.4±2.11 cm), body length (96.56±1.87 vs 99.89±2.32 cm) and chest girth (119.98±1.98 vs 137.12±2.8 cm). Kosali cattle are smaller in size and are well adapted to the existing agroclimatic conditions of the region. Appropriate breeding strategies and conservation models should be designed for overall improvement of this breed.

Redescription of Ventania avellanedae (Stylommatophora: Odontostomidae), a land snail endemic to the Ventania Mountain System, Argentina

Although the presence of apertural folds and lamellae is the most recognizable character of the Odontostomidae, some species lack them, mostly inAnctusMartens, 1860,BahiensisJousseaume, 1877 andMoricandiaPilsbry & Vanatta, 1898.EudioptusavellanedaeDoering, 1881 – a slender odontostomid species that lacks even the slightest trace of folds or lamellae in its shell aperture – was however transferred toOdontostomusby Pilsbry in 1902 on the basis of its building forward of the aperture-margins. It is currently placed in its own monotypic subgenus, Cyclodontina (Ventania) Parodiz, 1940, on the basis of about the same argument. In this paper we redescribe its shell morphology and, for the first time, describe the internal anatomy of the pallial complex and the reproductive and digestive systems. The presence of a spongy gland in the pallial complex; of a short penis sheath with no retractor muscle; of a bursa copulatrix duct longer than spermoviduct, and of an epiphallic gland strongly support the inclusion of this unusual species in Odontostomidae. The species is diagnosable by the sculpture of the protoconch, which is not smooth as previously described, but has waved axial ribs crossed by spiral lines in young specimens; the distinctive external and internal shape of the bursa copulatrix duct; the internal penis wall divided in three regions of different sculpture; the smooth inner wall of the vagina; the long and cylindrical epiphallus with a distal widening indicating the presence of an epiphallic gland, and the penis retractor muscle inserted in the distal end of a short flagellum. These characters support the validity ofVentaniaParodiz, 1940, different fromCyclodontinaBeck, 1837.

Morphological re-description ofAplysia depilans(Gastropoda: Anaspidea): new insights into the anatomy of the anaspideans

AlthoughAplysia depilansis a widely known European species and the type species of the genus, the distinctions that separate it from other related congeners are not entirely clear. Aimed at improving this scenario, a detailed morphological description is performed herein, showing some unprecedented and useful features. Based on our anatomical examination, this study has found the opaline gland to be dark in colour, as well as a metapodium with an indistinctly delimited pedal sucker, a crop divided into two equal chambers of similar volume by a circular muscle, gizzard plates arranged in groups, and a peculiar penial sheath structure. All of these characters appear to be significantly different from the other species, based on a review of the anatomical literature and several examined samples of ongoing studies. Our central objective is to provide new data on the anatomy of the type species of Aplysiidae; and, based on topological evidence, to propose a new terminology and possible homologies to some important characters, such as parapodia lobation, cephalic tentacles, crop, penial sheath, gizzard plates and visceral ganglion in anaspideans, for future phylogenetic analysis. The subgenusSubaplysiaMedina, Collins&Walsh, 2005 is regarded as a junior synonym of subgenusAplysiaLinnaeus, 1767.

Two new European species of the marine genus Tubificoides (Annelida: Clitellata: Naididae) with notes on the morphology of T. pseudogaster (Dahl, 1960)

Two new species of Tubificoides (subfamily Tubificinae), T. charlotteae n. sp. and T. mackiei n. sp., are described based on morphological analyses. Both species were flagged as potentially cryptic in a previous investigation, based on both mitochondrial and nuclear sequence data. Tubificoides charlotteae n. sp., known only from an intertidal site in southern Spain, is characterized by the lack of cuticular papillation, the possession of several needle-like hair chaetae in dorsal bundles, a cone-shaped penis sheath, and a rather large, muscular penial sac. It strongly resembles the north-west European, largely sublittoral species T. amplivasatus, but differs from this species in terms of body size, width of vas deferens, and the shape and size of both the ejaculatory duct and penial sac. Tubificoides mackiei n. sp., collected from the southeast coast of Norway and the west coast of Sweden, is characterized by the lack of cuticular papillae and hair chaetae, and the possession of a rather long penis sheath with a wide terminal opening. It shares several morphological features with the sympatric species Tubificoides pseudogaster, but is distinguished from the latter by the detailed morphology and length of the penis sheaths, the width of the atrium, and the lower maximal number of bifid chaetae in dorsal preclitellar bundles. The utility of an integrative comparative approach, combining molecules and morphology, for the identification and delineation of new taxa within Tubificoides is briefly discussed.

Two new acotylean flatworms (Polycladida) of two genera unrecorded in the Eastern Atlantic

This paper describes two new species of two genera of polyclad flatworms found in the Iberian Peninsula, Parviplana and Phaenoplana. Parviplana jeronimoi sp. nov. is a small-sized polyclad with yellowish-brown background colour and pale yellow ventral body; gonopores well separated, with corrugated ventral body wall between them; and prostatic vesicle with a penis papilla surrounded by a penis sheath, both housed in a wide male atrium. Phaenoplana caetaria sp. nov. is characterised by a yellowish-brown dorsal body, without tentacles, ejaculatory duct projects inside the prostatic vesicle, spherical prostatic vesicle, twisted penis rod, well-developed male atrium and elongated small Lang’s vesicle. This is the first record of the genera Parviplana and Phaenoplana in Europe, as well as in the Eastern Atlantic.

Histological, histochemical, and ultrastructural investigation of the male copulatory apparatus of Haminoea navicula (Gastropoda, Cephalaspidea).

Due to its biological and systematic importance, the morphology and function of the male copulatory apparatus of Haminoea navicula, a Cephalaspidea gastropod mollusk, was investigated by light and electron microscopy. These systems are poorly understood in haminoids, but are often used in the taxonomy of the genus. In H. navicula, the male copulatory apparatus comprises the penis within a penial sheath, a seminal duct and the prostate with two lobes. The penis is a muscular structure with a tip covered by spikes formed by muscular cells. The penial sheath consists of muscular tissue folds lined by an epithelium. Below this epithelium, polysaccharide-secreting cells and pigment cells were observed. A large number of vacuolar cells were found below the ciliated epithelium of the seminal duct. The proximal lobe of the prostate was formed by tubules that could be divided in basal, middle and apical zones, containing cells that secrete polysaccharides and proteins. The tubules of the prostate distal lobe contained a single type of secretory cells with vesicles that were stained by histochemical techniques for detection of polysaccharides and proteins. Ciliated cells were present along the tubules in both lobes of the prostate. This study revealed a complex prostate with five types of secretory cells, which secrete substances that should be involved in the maintenance and eventually also in the maturation of spermatozoa. A comparison with previous publications, shows that the male copulatory apparatus can differ substantially among cephalaspideans, even between H. navicula and non-European species attributed to this genus.

Four species of Tubifex Lamarck (Annelida: Oligochaeta: Naididae) from Tibet, China

Four species of Tubificinae (Oligochaeta: Naididae), Tubifex laxus n. sp., Tubifex gracilentus n. sp., Tubifex conicus He, Wang & Cui, 2012, and Tubifex tubifex (Müller, 1774) are reported from Tibet, China. T. laxus n. sp. is distinguished from allied species by relatively wide atria. T. gracilentus n. sp. differs from congeners in extremely thin and long penial sheaths. T. conicus is redefined as a species that lacks spermathecae. T. tubifex as redescribed here has slightly hirsute hair chaetae, cuticle rings around the penes and spermathecae with empty ampullae.

A new species of Camaenidae (Gastropoda, Pulmonata) from Nusa Penida and Lombok Islands, Indonesia: novelty in a well-known fauna

ABSTRACTA new species of camaenid land snail, Vulnus wallacei Páll-Gergely, Otani & Hosoda n. sp. is described from Nusa Penida and Lombok Islands, Indonesia. The new species is putatively classified into the genus Vulnus, which is only known so far from the Northern Maluku Islands. The genital anatomy, especially the presence of a well-developed penial sheath in V. wallacei, suggests a close relationship with Australian camaenids. However, the molecular phylogeny based on partial cytochrome c oxidase I, and 16S and 28S ribosomal RNA genes shows that the new species falls outside the cluster of all Australian Camaenidae.http://www.zoobank.org/urn:lsid:zoobank.org:pub:D28554D0-3578-4E95-8849-09EAFB7D30F7

Multi-locus phylogenetic analysis of the genus Limnodrilus (Annelida: Clitellata: Naididae)

Limnodrilus species are annelid worms distributed worldwide in various freshwater sediments. The systematics of Limnodrilus has chiefly been based on morphology, but the genus has not been subject to any closer phylogenetic studies over the past two decades. To reconstruct the evolutionary history of Limnodrilus, and to assess the monophyly of this genus and its systematic position within the subfamily Tubificinae (Annelida: Clitellata: Naididae), 45 Limnodrilus specimens, representing 19 species, and 35 other naidid species (representing 24 genera) were sampled. The data consisted of sequences of three mitochondrial genes (COI, 12S and 16S rDNA) and four nuclear markers (18S and 28S rDNA, Histone 3, and ITS). The phylogeny was estimated, using Maximum Likelihood and Bayesian analyses of concatenated data of seven DNA loci, as well as a multi-locus coalescent-based approach. All analyses strongly suggest that Limnodrilus is monophyletic, but only if the morphospecies L. rubripenis is removed from it. Limnodrilus rubripenis and (at least) Baltidrilus, Lophochaeta and some species attributed to Varichaetadrilus comprise the sister group to the clade Limnodrilus sensu stricto, and the latter is further divided into three well-supported groups. One of them contains morphospecies characterized by short cuticular penis sheaths and enlarged chaetae in anterior segments (L. udekemianus, L. silvani and L. grandisetosus). The second is a small group of species with moderately long penis sheaths, i.e., L. sulphurensis and L. profundicola. The third, and largest group, includes not only the multitude of cryptic species in the L. hoffmeisteri complex, but also other, morphologically distinct, species nested within this complex. All studied species in this large group have long penis sheaths, which are exceptionally long in L. claparedianus, L. maumeensis, and a form morphologically intermediate between L. claparedianus and L. cervix. The identification and classification of these groups provide a framework for directed sampling in further phylogenetic studies, and for revisionary work on the L. hoffmeisteri complex and other unresolved Limnodrilus species.

A new genus of the Bradybaenidae family (Gastropoda, Pulmonata) from Central Asia

On the Kugitangtau Ridge (western part of Pamiro-Alai mountain system) 16 specimens of a new species of molluscs referring to the nominative subfamily of the Bradybaenidae family have been found. The new taxon differs from all other species of this subfamily by total absence of all additional organs of female section of the reproductive tract (stylophore, additional sac, mucus glands, supraatrial bladder), bean-shaped short penis, and thick-walled penis sheath that attached at both proximal and distal ends. On the base of these characters the illustrated description of a new monotypic taxon Kugitangia hatagica Schileyko, Pazilov et Abdulazizova, gen. et sp. nov. is presented. Conchologically the new species does not differ reliably from Fruticicola fedtschenkoi and differs from Fruticicola perlucens mainly by the presence of fine granulation on the embryonic whorls.

Freshwater gastropods diversity hotspots: three new species from the Uruguay River (South America).

Background: The Atlantic Forest is globally one of the priority ecoregions for biodiversity conservation. In Argentina, it is represented by the Paranense Forest, which covers a vast area of Misiones Province between the Paraná and Uruguay rivers. The Uruguay River is a global hotspot of freshwater gastropod diversity, here mainly represented by Tateidae (genus Potamolithus) and to a lesser extent Chilinidae. The family Chilinidae (Gastropoda, Hygrophila) includes 21 species currently recorded in Argentina, and three species in the Uruguay River. The species of Chilinidae occur in quite different types of habitats, but generally in clean oxygenated water recording variable temperature ranges. Highly oxygenated freshwater environments (waterfalls and rapids) are the most vulnerable continental environments. We provide here novel information on three new species of Chilinidae from environments containing waterfalls and rapids in the Uruguay River malacological province of Argentina.Materials and Methods: The specimens were collected in 2010. We analyzed shell, radula, and nervous and reproductive systems, and determined the molecular genetics. The genetic distance was calculated for two mitochondrial markers (cytochrome c oxidase subunit I–COI- and cytochrome b -Cyt b-) for these three new species and the species recorded from the Misionerean, Uruguay River and Lower Paraná-Río de la Plata malacological provinces. In addition, the COI data were analyzed phylogenetically by the neighbor-joining and Bayesian inference techniques.Results: The species described here are different in terms of shell, radula and nervous and reproductive systems, mostly based on the sculpture of the penis sheath. Phylogenetic analyses grouped the three new species with those present in the Lower Paraná-Río de la Plata and Uruguay River malacological provinces.Discussion: Phylogenetic analyses confirm the separation between the Uruguay River and the Misionerean malacological provinces in northeast Argentina. These new endemic species from the Uruguay River add further support to the suggestion that this river is a diversity hotspot of freshwater gastropods (with 54 species present in this basin, 15 of them endemic). These endemic species from environments with rapids and waterfalls should be taken into account by government agencies before the construction of dams that modify those ecologic niches in the Uruguay River.

Limnodrilus sulphurensis n. sp., from a sulfur cave in Colorado, USA, with notes on the morphologically similar L. profundicola (Clitellata, Naididae, Tubificinae).

A new species of the tubificine genus Limnodrilus is described and COI barcoded from Sulphur Cave and associated springs in Colorado, USA. The habitats are characterized by high sulfide concentrations. The new species, L. sulphurensis, is distinguished from all congeners by the elongate, nearly parallel teeth of chaetae in its anterior segments. It has a penis sheath resembling that of L. profundicola; consequently, museum specimens and new collections are examined here to resolve some of the taxonomic confusion surrounding that widespread, but uncommon species.

Hunters and herders: Exploring the Neolithic transition in the rock art of Shuwaymis, Saudi Arabia

In Arabia the transition to a Neolithic economy is thought to be characterised by a shift to mobile pastoralism, rather than the traditional icons of the Neolithic such as sedentism and crop cultivation. However, in the absence of detailed archaeological research, the Early Holocene prehistory of central, northern and northwestern Saudi Arabia remains largely unknown. Here we use the engraved rock art recorded on 254 panels in Shuwaymis, Ha'il Province, and in particular depictions of hunting and herding scenes, to identify evidence on the character of the Neolithic transition in the region. Due to high levels of erosion it was not possible to carry out spatial analysis of the sites. However, the content and stratigraphic relationship of hunting and herding panels, re-engraving events, and cultural markers related to human figures were analysed. The results show that the engravings can be divided into an exclusive hunting period, where equids are frequently being hunted. Domestic cattle are often placed over and integrated into existing hunting scenes by re-engraving parts of the scene and turning hunting figures into herding figures. Cultural markers associated with human depictions such as headdresses and possible penis sheaths continue across both periods. The evidence in the rock art indicates that herding was adopted by local hunters. Moreover, the rock art shows that herders identified with the depicted hunters and that ibex hunting remained part of the image repertoire, and potentially of the subsistence economy, throughout the Holocene.

Persica qeshmensis gen. nov. sp. nov from the Persian Gulf (Platyhelminthes: Polycladida: Acotylea), with remarks on reproductive structures

A new genus of acotylean polyclad, Persica qeshmensis gen. nov. sp. nov. (Acotylea, Pleioplanidae), was collected from intertidal rocky shores of the Northern Persian Gulf, Iran. The genus Persica is established on the presence of small tentacles; tentacular and cerebral eyes; spermiducal bulbs; true seminal vesicle; prostatic vesicle of atomata-type; muscular coiled ejaculatory duct, provided with a stylet, absence of a vagina bulbosa or Lang’s vesicle. Persica qeshmensis is characterised by a sandy beige to light brown background colour, with pale brown microdots, light grey ventral body surface, coiled ejaculatory duct embedded in parenchymatous cell mass, elongated sigmoid stylet, a well-developed penis sheath located in a small male atrium, and with a non-muscular blind chamber extending anteriad from the vagina to the level of the genital sucker.http://zoobank.org/urn:lsid:zoobank.org:pub:FAA7AA0A-6954-47D0-A5B2-1A2EC04050C3

New species of Pheretima (Oligochaeta: Megascolecidae) from the Mt. Malindang Range, Mindanao Island, Philippines

We provide descriptions, with illustrations of internal structures, for 18 new species of Pheretima from Mt. Malindang, Misamis Occidental Province, Mindanao Island, Philippines. Among the 18 species, 11 belong to the P. sangirensis species group, characterized by having a pair of spermathecal pores in the intersegmental furrow of 7/8 and lacking penial sheaths in the copulatory bursae: P. maculodorsalis n. sp., P. tigris n. sp., P. immanis n. sp., P. lago n. sp., P. nunezae n. sp., P. boniaoi n. sp., P. malindangensis n. sp., P. misamisensis n. sp., P. wati n. sp., P. longiprostata n. sp., and P. nolani n. sp. One species, P. longigula n. sp., belongs to the P. montana species group, characterized by having a pair of spermathecal pores in the intersegmental furrow of 7/8 and penial sheaths in the copulatory bursae. Two species, P. vergrandis n. sp. and P. concepcionensis n. sp., are monothecal. Three species, P. adevai n. sp., P. lluchi n. sp., and P. potonganensis n. sp., belong to the P. darnleiensis species group, characterized by having either four or five pairs of spermathecae from vi to ix, with a fifth pair variably present in segment v. One species, P. subanensis n. sp., is athecate. All species described here from the Mt. Malindang Range are probably native rather than introduced, and probably do not represent range extensions of species known from neighboring islands in Southeast Asia. We provide an identification key to the Pheretima species from Mt. Malindang.

Sylphellapuccoon gen. n., sp. n. and two additional new species of aquatic oligochaetes (Lumbriculidae, Clitellata) from poorly-known lotic habitats in North Carolina (USA).

Three new species of Lumbriculidae were collected from floodplain seeps and small streams in southeastern North America. Some of these habitats are naturally acidic. Sylphella puccoon gen. n., sp. n. has prosoporous male ducts in X–XI, and spermathecae in XII–XIII. Muscular, spherical atrial ampullae and acuminate penial sheaths distinguish this monotypic new genus from other lumbriculid genera having similar arrangements of reproductive organs. Cookidrilus pocosinus sp. n. resembles its two subterranean, Palearctic congeners in the arrangement of reproductive organs, but is easily distinguished by the position of the spermathecal pores in front of the chaetae in X–XIII. Stylodrilus coreyi sp. n. differs from congeners having simple-pointed chaetae and elongate atria primarily by the structure of the male duct and the large clusters of prostate cells. Streams and wetlands of Southeastern USA have a remarkably high diversity of endemic lumbriculids, and these poorly-known invertebrates should be considered in conservation efforts.

Nuptial Gifts inPomacea canaliculata(Ampullariidae, Caenogastropoda): Experimental and Field Evidence about Their Function

Pomacea canaliculata is a South American apple snail that shows a multiple mating behavior. The copulations are frequent and long lasting, and consequently the males have to face strong sperm competition. The outer gland at the base of the penis sheath secrets drops of mucus that females eat during copulation. These mucus drops are nuptial gifts, and the occurrence of them is the only known instance of this behavior in molluscs. We investigated three possible functions of the gift-giving behavior in P. canaliculata based on three hypotheses: prowler deterrence, male mating effort and paternal investment. We also quantified the frequency of nuptial gifts in two populations of P. canaliculata and its possible role in male competition. We found no aversive reaction neither in females nor in males, but females were attracted to the mucus secretion. The consumption of artificial nuptial gifts (homogenates of the outer sheath gland) had no effect on the copulation duration nor on the total number of eggs and egg masses laid by females. In the field, the frequency of nuptial gifts was almost ten times greater in the population with the highest density of snails, indicating a much higher rate of production of nuptial gifts. The proportion of couples with both nuptial gifts and a prowler males attached was significantly higher than expected by chance in the population with the highest population density. Even though our results give no support for the three hypothesized functions for the nuptial gifts in P. canaliculata, this study revealed a possible different role in male competition: the enticement of the female to remain in copulation when the other males are trying to gain access.