The male copulatory system of european pea crabs (crustacea,brachyura, pinnotheridae)

The male copulatory system of the European pinnotherid species Pinnotheres pisum, Pinnotheres pectunculi, and Nepinnotheres pinnotheres was investigated by gross morphology, scanning electron microscopy, histological methods, and confocal laser scanning microscopy. The brachyuran copulatory system is consistently formed by paired penes and two pairs of abdominal appendages, the gonopods, functioning in sperm transfer. In pinnotherids, the long first gonopods transfer the sperm mass into the female ducts. The first gonopod has the ejaculatory canal inside that opens both basally and distally. The second gonopod is solid, short, and conical. During copulation, the penis and the second gonopod are inserted into the basal lumen of the first gonopod. While the penis injects the sperm mass, the second gonopod functions in the transport of spermatozoa inside the ejaculatory canal toward its distal opening. The second gonopod is adapted for the sealing of the tubular system in the first gonopod by its specific shape and the ability to swell. Longitudinal cuticle foldings of the second gonopod hook into structures inside the first gonopod. The second gonopod can interact with the penis during copulation by a flexible flap separating the lumina in which the second gonopod and the penis are inserted. J. Morphol., 2012. © 2012 Wiley Periodicals, Inc.     

Functional morphology of the copulatory system of box crabs with long second gonopods (Calappidae,Eubrachyura, Decapoda,Crustacea)

Male True Crabs use two pairs of gonopods to deliver mating products during copulation. Commonly, the second pair is shorter than the first pair, and most research to date has focused on species with short second gonopods. We investigated male and female copulatory organs in Calappula saussurei and Calappa pelii, two species of box crabs (Calappidae) with second gonopods which are longer than the first pair. Scanning electron microscopy and histological cross sectioning show that the female copulatory system is unique in several aspects: the genital duct is part concave and part simple type. The seminal receptacle is divided into two chambers, a ventral chamber of ectodermal and mesodermal origin, and a dorsal chamber of ectodermal origin. This dorsal chamber is the location of spermatophore reception during copulation. A sperm plug closes the dorsal chamber off. We propose that long second gonopods deliver male mating products directly into the dorsal chamber. To date, spermatophore reception has been associated with the mesodermal tissue of the seminal receptacle. The copulatory system of box crabs with long second gonopods shows novel deviations from this general pattern. J. Morphol. 276:77–89, 2015. © 2014 Wiley Periodicals, Inc.     

The morphology of the reproductive system in the crab Percnon gibbesi (Decapoda: Brachyura: Grapsoidea) reveals a new combination of characters in Thoracotremata

Recent studies revealed a high diversity of reproductive structures in heterotreme brachyurans, while those of Thoracotremata seem rather uniform. Yet, there still is a huge lack of data in this group as only few species have been studied with respect to their reproductive system. The phylogenetic position of Percnidae is ambiguous. Recent molecular studies place it within polyphyletic grapsoids. We herein study the reproductive morphology of Percnon gibbesi using histology, scanning electron microscopy, micro‐computed tomography and 3D‐reconstructions to test whether this species shows the characteristic thoracotreme pattern. Our results reveal that the male copulatory system conforms to other thoracotremes. It is composed of two pairs of pleopods (gonopods) and likewise paired penes. The first gonopod is relatively long. It possesses a bent terminal process with a distal opening of the ejaculatory canal, a character also present in other grapsoids. The second gonopod is short and terminates in an apical girdle. The female reproductive system reveals a combination of characters, so far unknown for thoracotremes. The paired oviducts do not lead into the seminal receptacles, but run into separate cuticular ducts joined with the vaginae. Accessory sperm storage organs, the bursae, are also connected to the vaginae. Bursae have previously only been described in heterotreme crabs. The data presented in this study reveals a higher diversity of thoracotreme reproductive systems than anticipated.     

Morphology and function of the reproductive system of representatives of the genus Uca

The morphology of the reproductive organs of three species of fiddler crabs, Uca ecuadoriensis, Uca c.f. forcipata, and Uca tangeri were investigated to subsequently produce a model of their mode of operation. Vulva, vagina, and spermatheca in females, and the first and second gonopods in males were examined by applying histological techniques and electron microscopy. In all three species, vulva and vagina conform to the concave type, and the spermatheca complies with the ventral type. The tissue of the oviduct orifice is enlarged and bulges into the lumen of the spermatheca. Differences between the three species are apparent in the organization of the spermatheca, especially in the distribution and structure of glandular epithelium: In U. ecuadoriensis and U. c.f. forcipata the largest proportion of the spermathecal wall is lined with cuticle and only a small area consists of glandular epithelium, while in U. tangeri almost all of the lining is glandular. Furthermore, the glandular epithelia of the species differ in their histology and ultrastructure: In U. ecuadoriensis it is tubular and multilayered, while in U. c.f. forcipata it is mono‐layered. U. tangeri finally has both forms of this tissue. In the males, the terminal segments of the first gonopod exhibit a tight fit to female organs and narrow, tightly sealed sperm channels. These features suggest a tendency towards minimizing loss of fluids, which can be interpreted as an adaptation to mating on land. The tight fit of male gonopod and female opening seem to be protection from interbreeding, which points toward a strong sexual selection. In the terrestrial environment, these originally aquatic organisms experience serious competition for resources; therefore there is pressure on successful reproduction. According to the current results a model of the process of fertilization and egg‐laying involving the investigated organs was generated. J. Morphol., 2010. © 2010 Wiley‐Liss, Inc.     

Courtship and sperm transfer in Charinus neocaledonicus Kraepelin, 1895 and Charinus australianus (L. Koch, 1867) (Arachnida, Amblypygi, Charinidae)

The Charinus australianus group is a well-defined species group characterised by rounded, cushion-like female gonopods. Before the present study, the morphology of the gonopods and their function have not been understood. This paper describes courtship behaviour, spermatophore morphology, and the morphology of the female genitalia of Charinus neocaledonicus Kraepelin, 1895 and C. australianus (L. Koch, 1867). Courtship behaviour, though different in details, is similar to that of many other species. The spermatophores are large and soft and carry very small sperm packages, each with a short stalk. After sperm transfer, the spermatophore may be eaten by the female. The spermatophore thus transfers not only spermatozoa but also nutritious paternal investment to the female. Each female gonopod is equipped with a seminal receptacle consisting of an atrium and a spacious inner receptacle. The cover of the atrium can be elevated by high blood pressure and pulled back by a group of muscles attached to the inner part of the receptacle. The female probably picks up the sperm packages with the atria of her receptacles. The observations are compared to those on other amblypygids, and the evolution of different types of spermatophores and of gonopods with seminal receptacles is discussed.     

The reproductive system of Limnopilos naiyanetri indicates a thoracotreme affiliation of Hymenosomatidae (Decapoda,Eubrachyura)

The eubrachyuran Hymenosomatoidea is widely distributed in tropical and subtropical regions ranging from marine to freshwater habitats. Even though the biology of this taxon has been studied to some extent, its phylogenetic relationships are not resolved. Based on different morphological characters, some authors suggested a close affinity of hymenosomatid crabs to heterotremes. However, many of these characters are ambiguous, and the few molecular studies did not provide convincing solutions either. To address this issue, we studied the reproductive system of the hymenosomatid freshwater species Limnopilos naiyanetri Chuang and Ng, 1991 using histology and scanning electron microscopy. The females show the characteristic organization of the paired eubrachyuran reproductive system. Additionally, a bursa (an accessory sperm storing cuticle cavity) is present. The male copulatory system is characterized by paired long first and short second gonopods, and a pair of sternal gonopores equipped with a penis. Both, the female and male reproductive organs reveal a number of similarities to thoracotreme crabs. The seminal receptacle is lined by a very thin cuticle and by a mono-layered glandular epithelium. The male gonopods and the sternal genital opening also resemble the thoracotreme condition. Thus, our results indicate that Hymenosomatidae are most likely part of the Thoracotremata.     

Sperm displacement in a millipede? An investigation into the genital morphology of the southern African spirostreptid millipede Orthoporus pyrhocephalus

Male and female genital morphology of the spirostreptid millipede Orthoporus pyrhocephalus was examined by conventional and scanning electron microscopy techniques. The relative syncopulatory positions of the genitalia were established through dissections of pairs in copula. Male gonopods bear scoops and regions of pitted spines. both of which are similar in form to morphological structures implicated in insect sperm displacement. Consideration of the position of the oviduct-spermathecal junction in females predicts that displacement is restricted to a sperm removal mechanism. The importance of spermathecal shape in determining sperm precedence patterns is discussed. The orientation of the genitalia during copulation indicates that sperm displacement is plausible and a mechanism of gonopod action is suggested.     

Chelodesmid studies. XIII. A synopsis of the Brasilian tribe Strongylomorphini

The new diplopod tribe Strongylomorphini (fam. Chelodesmidae) is proposed for the two Brasilian genera Strongylomorpha and Brasilodesmus, characterized by the distal torsion of the solenomerite and form of the apical end of the prefemoral process, of the male gonopod. Strongylomorpha has been of uncertain status since 1897, but study of its type species shows the name to be a senior synonym of Erythrodesmus Silvestri, 1902, Neocamptomorpha Schubart, 1954, and Camptomorphoides Schubart 1962. Drawings of the gonopods are given for several old species, made from Iectotype specimens, and a list of the names considered referable to Strongylomorpha. The new species Brasilodesmus austrocrucis is described from Santa Catarina, Brasil.     

Phylogeny, biogeography and a new taxonomy for the Gecarcinucoidea Rathbun, 1904 (Decapoda: Brachyura)

Phylogenetic relationships of gecarcinucoid freshwater crabs were investigated, based on morphology of the male second gonopod. In addition, a comparison of sequences from the mitochondrial large subunit rRNA gene helped to resolve the phylogeny of this group and relationships to other Old World freshwater crabs. As a result, we recognise two sister groups within the Gecarcinucoidea, the African Deckeniidae and the Asian Gecarcinucidae. Deckeniidae includes three monophyletic clades, the Deckeniinae in East Africa and on the Seychelles, the West African Globonautinae and the Malagasy Hydrothelphusinae. Gecarcinucidae comprises two sister groups, the Gecarcinucinae with representatives in Sri Lanka, India and southeast Asia, and the Parathelphusinae in India, southeast Asia, the Sundaic Islands and Australia. Interpretation of our phylogenetic results leads us to propose a new biogeographic hypothesis for the Gecarcinucoidea. Most likely, the gecarcinucoid freshwater crabs have an African origin; their distribution can be explained by successive events of dispersal. This model can be correlated with palaeogeographical and palaeoclimatological data for the Cenozoic, suggesting a gecarcinucoid dispersal to Asia via the “Lemurian Stepping-Stones”, a chain of islands in the West-Indian Ocean that were emergent in times of low sea levels during the Oligocene.     

Morphological diversity of setae on the second maxilliped of fiddler crabs (Decapoda: Ocypodidae) from the southwestern Atlantic coast

Fiddler crabs are deposit feeders, and use the setae on their mouth appendages to manipulate sediment particles to extract food. The number of spoon‐tipped setae on the second maxilliped is frequently related to the distribution of fiddler crabs on estuarine sediments, but no study has compared the morphological diversity of these setae among multiple fiddler crab species. Here, we describe and classify the setae of the second maxillipeds of the nine Uca spp. known from the Brazilian coast. The second maxilliped of each species was examined by scanning electron microscopy. Six types of setae (five papposerrate, and one pappose) were described on the meropodite of the second maxilliped. Among the papposerrate setae, one type had a spoon‐like tip, and the morphology of this type, especially the degree of curvature, differed between species. Members of Uca leptodactylus, U. uruguayensis, and U. maracoani had highly concave spoon‐tipped setae. In U. rapax and U. cumulanta, the setal tip was moderately curved, while in U. thayeri, U. burgersi, and U. mordax, this curvature was slight. At the other extreme, the meropodite of the second maxilliped of U. vocator lacked setae altogether. This is the first study that describes differences in the degree of curvature of spoon‐tipped setae in fiddler crabs. This trait may be strongly related to the distribution of these fiddler crabs on different estuarine substrates.     

Two new species of fresh water crab (Brachyura: Pseudothelphusidae) from Serranía de Los Paraguas, Cordillera Occidental, Colombia

Two new species of freshwater crabs of the genus Hypolobocera from Serranía de Los Paraguas, Cordillera Occidental, Colombia, are described. Hypolobocera solimani n. sp. is closely related to H. alata Campos 1989, but can be distinguished from it by smooth upper margin of third maxilliped merus, the size and shape of apex of first gonopod, and the internal lobe or papilla of spermatic channel, which is concave, raised, with ends with minute papillae or rounded tubercles. Hypolobocera triangula n. sp. is very similar to H. rotundilobata Rodríguez 1994, but differs from it by the shape and size of the lateral lobe, an oblique basal ridge of tubercles and by the apex of first gonopod. With the two new species, the total number of valid members of the genus Hypolobocera known from western Colombia or biogeographic Chocó is 20.     

Spermatophore transfer in the hermit crab Clibanarius vittatus (Crustacea,Anomura, Diogenidae)

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.     

Genitalia Fitting,Mating Behaviour and Possible Hybridization in Millipedes of the Genus Craspedosoma (Diplopoda,Chordeumatida, Craspedosomatidae)

Abstract The functional anatomy of the extremely complex copulatory organs of the millipede Craspedosoma transsilvanicum Verhoeff, 1897, was investigated by scanning electron microscopy and serial semi-thin sectioning after fixation of the animals by freezing in copula. There is no male organ for sperm transfer which inserts into the receptacula seminis. Sperm secretion is only brushed over the openings of the receptacula by cuticular projections of the anterior gonopods (‘brush’). Other parts of the gonopods (projections of the cheirites, podosternite) bring the brush and the openings of the receptacula in the proper position. Examination of the gonopods from series of Craspedosoma from locations near Vienna showed that there are intermediary specimens between the nominal species C. transsilvanicum and C. alemannicum Verhoeff, 1910. Obviously, a mechanical isolation mechanism, as supposed by Verhoeff, does not exist between these nominal species. At the beginning of a copulation, the male forces the female into the mating position. When touched by males, the females try to evade them by rolling up. The possibilities are discussed that females thereby test the actual fitness of males, and that males use their clasper-like copulatory organs to prevent females from escaping.     

Morphologisch-histologische untersuchungen an den geschlechtsorganen der amblypygi unter besonderer Berücksichtigung von Tarantula marginemaculata C. L. Koch (Arachnida)

Zusammenfassung Das männliche Genitalsystem von Tarantula besteht aus paarigen Hoden, Lateraldrüsen, Ventraldrüsen und dem Genitalatrium mit dem Genitalanhang.Die Spermatozoen entwickeln sich in Spermatocysten. Sie sind zunachst langgestreckt und korkenzieherförmig. Später rollen sie sich ein and encystieren sich. In diesem Zustand werden sie in paarigen Vesicula seminalis gespeichert.Die Ventraldriisen produzieren durch holokrine Sekretion ein granuläres Sekret. Das Produkt der Lateraldrüsen ist homogen und hyalin. Beide Sekrete mischen sich nicht; sie werden in großen Sekretreservoiren gespeichert.Die Genitalanhang entsteht aus paarigen Gonopoden, die sich zunächst teilen und darn zusammenlegen und so ein hohles, kompliziertes Organ bilden.Die Spermatophore ist nicht vorgebildet, wenn das Männchen sich anschickt, sie abzusetzen. Die beiden Sekrete laufen zunächst entlang zweitr Ventralrinnen zu zwei ventralen Öffnungen. Dort werden sie am Untergrund befestigt und dann durch Anheben des Körpers zum Stiel ausgezogen. Danach werden die Ventralrinnen geschlossen, und das Sekret fließt in den zentralen Hauptraum des Genitalanhangs, der als Negativ-Form für den oberen Teil der Spermatophore dient. Dieser wird anschließend durch eine dorsale Öffnung herausgezogen.Die weiblichen Organe bestehen aus paarigen Ovarien, Ovidukten und Oviduktanhängen, einem unpaaren Uterus und dem. Genitalatrium mit den Gonopoden.Die Oocyten treten fresh aus dem Ovar aus, mit dem sic durch einen Funiculus verbunden bleiben. In der Leibeshöhle vollzieht sich der Dottereinbau in zwei Phasen; die zweite beginnt normalerweise nach der Paarung. Doch bleiben immer einige ruhende Oocyten, die nicht die zweite Vitellogenese-Phase beginnen. Kurz vor der Eiablage dehnen sich die Funiculi stark und lassen die Eier wahrscheinlich zurück ins Ovar schlüpfen.Nach der Paarung werden außerdem die Ovarien, Ovidukte und Oviduktanhänge sekretorisch tätig. Sie liefern ein aus fädigen Elementen bestehendes Sekret, in das viele Hämocyten einwandern. Vor der Eiablage tritt dieses Material aus der Geschlechtsöffnung und bildet den Brutsack.Das weibliche Genitalatrium ist ein weiter Baum. Die Gonopoden sind Schwellkörper, die dem Genitaloperculum innen aufsitzen. Bei Tarantula tragen sie je ein klauenartiges Sklerit, mit dem die Samenpakete aus den Spermatophoren gerissen werden. Das Sperma wird in zwei Receptacula seminis gespeichert, deren Öffnungen direkt unter den Basen der Sklerite liegen. Charinus brasilianus besitzt keine solchen Sklerite und keine Receptacula; die Spermien werden in einer hinteren Ausbuchtung des Genitalatriums gespeichert.Bei jeder Eiablage werden alle Spermien aufgebraucht. Bei Häutungen bleibt das Sperma in der Exuvie und geht verloren. Die Weibchen miissen sich darum vor jeder Fortpflanzungsperiode erneut paaren.

---

Studies on the functional morphology of the genital organs of the amblypygi, especially of Tarantula marginemaculata C. L. Koch (Arachnida)

Summary The male genital system of Tarantula consists of paired testes, ventral glands, lateral glands, and the genital chamber with the cone like spermatophore organ.Spermatogenesis occurs in spermatocysts. Mature spermatozoa first are corkscrew like in shape but later become rolled up and encysted. They are stored in a pair of vesicula seminalis.In the ventral glands, secretion is holocrinous and a granular substance is formed. The lateral glands produce a transparent, homogenous material. Both substances do not mix; they are stored in large reservoirs.The cone like spermatophore organ is a complex structure formed by a pair of gonopods which first splits into two paires and later unites to form a hollow organ with a complicated system of cavities.No precursor of a spermatophore exists when a male starts depositing the spermatophore. The secreted material first runs along latero-ventral tubes to two ventral openings. There, it is fixed to the substrate and formed to the spermatophore stalk by the male's rising its body. Thereafter, the central cavity of the spermatophore organ is filled with secreted material and acts as a matrix which presses the upper parts of the spermatophore. This is finally pulled out through a mid-dorsal opening.The female organs consist of paired ovaries and oviducts, an unpaired uterus, and the genital chamber with the gonopods. The oocytes develop outside the ovary but remain fixed to it by a solid funiculus. There are two phases of vitellogenesis, the second one is started after mating. But there are allways a number of resting oocytes which do not enter the second phase of vitellogenesis. Since whip spiders may live for many years and may lay egss one to three times a year these are stored for later breeding periods. Before oviposition, the egg stalks widen, and the eggs finally pass through the funiculi into the ovary.Mating not only induces the second phase of vitellogenesis but also causes the ovary and oviducts to secret a filamentous material which is invaded by many haemocytes. Immediately before oviposition, this material is extruded. It surrounds the eggs and later hardens and forms the egg sac.The female genital atrium is a broad and wide cavity. The gonopods are two protrudible organs which, like the male organs, originate from the inner wall of the genital operculum. In Tarantula, each gonopod bears a claw like sclerite pointed backwards and inwards. By means of these sclerites the sperm packages are pulled out of the spermatophore. Simultaneously, the sperm is pressed out of the sperm packages, which may remain underneath the sclerites for many days, and sucked into two seminal receptacles laying just beneath the bases of the claw like sclerites. In Charinus brasilianus, the gonopods are cone like and lack sclerites and seminal receptacles. The sperm, in this species, is stored within a posterior pocket of the genital atrium.At oviposition, all stored sperm is used up, and at each molt all sperm is lost. Females therefore have to be reinseminated after breeding and molting.

---

---

Wir danken der Deutschen Forschungsgemeinschaft für eine Unterstützung durch Sach- und Personalmittel.     

A new species of Deiratonotus (Crustacea: Brachyura: Camptandriidae) found in the Kumanoe River Estuary, Kyushu, Japan

Camptandriid crabs collected in the Kumanoe River Estuary, Kyushu, Japan were studied on the basis of morphological characters and molecular analysis. As a result, a new species, Deiratonotus kaoriae, was recognized. These crabs were found mainly in a creek of the sandy tidal flat within the Kumanoe River Estuary. The new species shares a very diagnostic character, the presence of a transverse ridge on the carapace, with D. cristatus (de Man, 1895) and differs markedly from the other congeners that lack this feature. The new species, however, differs from D. cristatus in the absence of harpoon-shaped setae on the subdistal end of the first gonopod and the presence of an extremely reduced second abdominal segment. According to a molecular analysis based on 12S+16S mitochondrial rRNA gene sequences, with Cleistostoma dilatatum (de Haan, 1833) and Camptandrium sexdentatum Stimpson, 1858 as outgroups, Deiratonotus kaoriae is more closely related to D. cristatus than to D. japonicus (Sakai, 1934).     

Segmentation of the millipede trunk as suggested by a homeotic mutant with six extra pairs of gonopods

Background

The mismatch between dorsal and ventral trunk features along the millipede trunk was long a subject of controversy, largely resting on alternative interpretations of segmentation. Most models of arthropod segmentation presuppose a strict sequential antero-posterior specification of trunk segments, whereas alternative models involve the early delineation of a limited number of ‘primary segments’ followed by their sequential stereotypic subdivision into 2ⁿ definitive segments. The ‘primary segments’ should be intended as units identified by molecular markers, rather than as overt morphological entities. Two predictions were suggested to test the plausibility of multiple-duplication models of segmentation: first, a specific pattern of evolvability of segment number in those arthropod clades in which segment number is not fixed (e.g., epimorphic centipedes and millipedes); second, the occurrence of discrete multisegmental patterns due to early, initially contiguous positional markers.

Results

We describe a unique case of a homeotic millipede with 6 extra pairs of ectopic gonopods replacing walking legs on rings 8 (leg-pairs 10-11), 15 (leg-pairs 24-25) and 16 (leg-pairs 26-27); we discuss the segmental distribution of these appendages in the framework of alternative models of segmentation and present an interpretation of the origin of the distribution of the additional gonopods. The anterior set of contiguous gonopods (those normally occurring on ring 7 plus the first set of ectopic ones on ring 8) is reiterated by the posterior set (on rings 15-16) after exactly 16 leg positions along the AP body axis. This suggests that a body section including 16 leg pairs could be a module deriving from 4 cycles of regular binary splitting of an embryonic ‘primary segment’.

Conclusions

A very likely early determination of the sites of the future metamorphosis of walking legs into gonopods and a segmentation process according to the multiplicative model may provide a detailed explanation for the distribution of the extra gonopods in the homeotic specimen. The hypothesized steps of segmentation are similar in both a normal and the studied homeotic specimen. The difference between them would consist in the size of the embryonic trunk region endowed with a positional marker whose presence will later determine the replacement of walking legs by gonopods.     

A new species and record of branchial parasitic isopods (Crustacea: Isopoda: Bopyridae: Pseudioninae) of porcellanid crabs from the Philippines

Branchial bopyrids infesting porcellanid crabs from the Philippines were investigated based on intertidal collections made in 1999-2000. Crabs of the genus Petrolisthes collected from sites in the northern Philippines were examined and two parasite species were found. One new pseudionine species found infesting Petrolisthes sp. [cf. Petrolisthes asiaticus (Leach)] is described as Aporobopyrus galleonus (prevalence 6.1%); this species is distinguished from other members of the genus by a setose palp on the maxilliped of the females, barbula morphology, and male characters including the possession of pleopods. This represents the second described species of Aporobopyrus from the Philippines, and the first from porcellanid crabs. In addition, Pleurocrypta macrocephalaNierstrasz and Brender à Brandis, 1923 (originally described from Indonesia) was found infesting the same unidentified Petrolisthes sp. (prevalence 2.6%); this is the first report of the species from the Philippines.     

New species of the Lithobiid genus <Emphasis Type="Italic">Hessebius</Emphasis> Verhoeff, 1941 (Lithobiomorpha,Lithobiidae) from Eastern Kazakhstan

Two new species, Hessebius golovatchi Farzalieva, sp. n. and Hessebius zalesskajae Farzalieva, sp. n., are described based on material from the Dzungarian Alatau Mountains, Eastern Kazakhstan. The female of H. golovatchi sp. n. differs from all the previously known species of the genus in the presence of 3 + 3 spurs on the gonopod, while H. zalesskajae sp. n. is similar to H. perelae Zalesskaja, 1978 but differs in some structural details of the male and female gonopods.     

Male reproductive system of the arrow crab Stenorhynchus seticornis (Inachoididae)

Our aim was to describe the reproductive system of males and the formation of sperm packages in the seminal receptacle (SR) of recently mated females of the arrow crab Stenorhynchus seticornis. The male reproductive system was analyzed, and was described using light microscopy and histological and histochemical methods. The first pair of gonopods was described by means of scanning electron microscopy. Additionally, the dehiscence of spermatophores was tested using samples obtained from the vas deferens of males and from the seminal receptacle of recently mated females. Testes were tubular type, and each vas deferens consisted of three regions: the anterior vas deferens (AVD), including a proximal portion that was filled with free spermatozoa and a distal portion contained developing spermatophores; the median vas deferens (MVD) that contained completely formed spermatophores; and the posterior vas deferens (PVD), which contained only granular secretions. The accessory gland, which was filled with secretions, was located in the transition region between the MVD and the PVD. The spermatophores from the MVD were of different sizes, and none of them showed dehiscence in seawater, whereas those spermatophores in contact with the seminal receptacle were immediately broken. The ultrastructure of the gonopods revealed the presence of denticles at the distal portion, which contribute to the mechanical rupture of the spermatophore wall during the transfer of sperm. The contents of the PVD and accessory gland of males are transferred together with the spermatophores, and are responsible for the secretions observed among the sperm packets in the SR of the female. We suggest that these secretions formed the layers found in the SR of recently mated females, and may play a role in sperm competition in arrow crabs.