The hermit crab Sympagurus dimorphus (Anomura: Parapaguridae) at the edge of its range in the south-western Atlantic Ocean: population and morphometry features

Sympagurus dimorphus is one of the 12 hermit crab species recorded for Argentinean waters. Despite the high abundance registered in some scallop fishing grounds, its biology remains little known. In the present study, we analysed some population features of S. dimorphus living in symbiosis with Epizoanthus paguricola from a series of samples taken in the Argentine Sea, south-western Atlantic Ocean. Our results showed that S. dimorphus was commonly found from 40ºS to lower latitudes, in a patchy distribution along the shelf-break front. The overall sex ratio was 1:1. The smallest ovigerous female measured 6 mm in cephalothoracic shield length and this size was used as parameter to define the size of juveniles. The sex ratio size class pattern corresponded to Type IV or anomalous curve. S. dimorphus is a dimorphic species, as evidenced by the larger size of the males and the positive allometric growth of the right cheliped. The species also showed asymmetry, with the left uropod always larger than the right one. To the best to our knowledge, this is the first report on population features and relative growth for a member of the genus, based on long-term sampling. This species presents a patchy distribution along the shelf-break of Argentina. Its density tended to decrease over the five-year sampling period regarding the recruitment of hermits associated with colonies of zoanthids. In addition, the relatively homogeneous nature of this refuge does not seem to influence the growth of the hermit crab, which presents sexual dimorphism in relation to the sex/size conditions.     

A revision of the genus Pandalus (Crustacea: Decapoda: Caridea: Pandalidae)

The genus Pandalus Leach, 1814, is revised based upon the abundant material from collections in various museums or institutions in the world. Altogether 20 species are recognized which appear to form five groups. Nineteen species are recognized in Pandalus, three of which are described as new: P. curvatus from southern Japan, and P. chani and P. formosanus from Taiwan. Four informal species groups are also recognized within the genus: P. montagui group (P. montagui Leach, 1814; P. borealis Krøyer, 1838; P. goniuruStimpson, 1860; P. jordani Rathbun, 1902; P. tridens Rathbun, 1902; and P. eous Makarov, 1935); P. stenolepis group (P. stenolepis Rathbun, 1902; P. curvatus sp. nov.); P. hypsinotus group (P. hypsinotus Brandt, 1851; P. danae Stimpson, 1857; P. prensor Stimpson, 1860; P. gracilis Stimpson, 1860; P. gurneyi Stimpson, 1871; P. nipponensis Yokoya, 1933; P. teraoi Kubo, 1937; P. chani sp. nov.; and P. formosanus sp. nov.); and P. platyceros group (P. platyceros Brandt, 1851; and P. latirostris Rathbun, 1902). The P. platyceros group appears to be most closely related to the genus Pandalopsis Bate, 1888, but Pandalus is retained as a possible paraphyletic group. Protandrous hermaphroditism is known in all but two species of the genus (P. curvatus and P. formosanus), for which only specimens of either male or female have been available. Pandalus propinqvus G. O. Sars, 1870, is transferred to a new monotypic genus Atlantopandalus, because of its lack of hermaphroditism and possession of some unique morphological characters, including one indicating a close relationsip to Dichelopandalus Caullery, 1896. All species are fully described and illustrated. The affinities and important morphological variations of the species are discussed. A key for adults is presented for the identification of the species. Biogeography of the genus is briefly discussed.     

Behavioural ecology of Australian gall thrips (Insecta,Thysanoptera)

Collections, observations and experiments were used to investigate the behavioural ecology of gall thrips (Thysanoptera: Phlaeothripidae) in New South Wales and Queensland, Australia. Data are presented on aspects of gall morphology, male and female morphology, behaviour, life cycles, and sex ratios for six gall-forming species, five species of inquilines (invaders that do not form galls), and one genus that uses secretions to glue phyllodes (modified petioles) together. During gall foundation on phyllodes of Acacia pendula, females of Kladothrips rugosus Froggatt fight other females to the death, males fight other males to the death, and one female or one adult of each sex remains alive within the gall to breed. In addition to the live adults, half of newly found galls contained dead bodies of from one to 13 males and females, which were apparently killed in fights. In Oncothrips tepperi Karny, which forms galls on Acacia oswaldii, single females found new galls, and females engage in lethal fighting during the period from gall initiation until closure. First-generation broods of Oncothrips tepperi comprise winged males and winged females with a sex ratio of about 1:6 female biased. Each gall also contains several wing-reduced adults with larger forelegs than winged adults, which probably either fight among themselves or defend their siblings from gall invaders. Adults of Oncothrips tepperi breed in the galls for two or more generations, whereas in all of the other species studied on Acacia only one generation occurs in a gall. Females of the inquiline Koptothrips flavicornis invade young, first-generation galls of Oncothrips tepperi, kill the foundling female, and produce their own offspring. Single females of Oncothrips antennatus (Moulton) form galls on Acacia aneura, and apparently do not fight. Winged females of Oncothrips antennatus have smaller forelegs, relative to their body size, than do winged females of Oncothrips tepperi. In Onychothrips arotrum Mound and Onychothrips tepperi (Uzel), single females from galls on Acacia aneura. In each species, females engage in lethal fighting during gall initiation. The sex ratio of Onychothrips arotrum broods is about 1:18 female biased. The inquiline Csirothrips watsoni Mound invades galls of Onychothrips arotrum, apparently after most or all of the offspring have left, and breeds inside. Females of this inquiline will kill live Onychothrips arotrum inside the galls, and they apparently plug gall entrances with cast O. arotrum exuviae. Iotatubothrips crozieri Mound and Crespi is involved in the formation of large, woody galls on stems of Casuarina, perhaps in association with a microorganism. They breed in these galls for many generations. Galls contain several to thousands of individuals, and the adult sex ratio is about 1:4 female biased. Adults of the inquilines Thaumatothrips froggatti and Phallothrips houstoni Mound and Crespi invade these galls, kill the Iotatubothrips adults, and breed therein. The Iotatubothrips occasionally attempt, ineffectually, to fight off the invaders, and they apparently make partitions within the gall to protect themselves from takeover. Adults of Lichanothrips spp. glue phyllodes of Acacia harpophylla together using eggs and patches of secretion, and they breed in the resultant narrow space. Xanothrips xantes Mound breed in these spaces after the Lichanothrips have left. Fighting in Kladothrips rugosus, Oncothrips tepperi and Onychothrips tepperi involves two adults rearing up head to head, sparring with their enlarged, armed forelegs raised, and attempting to grasp and hold their opponent with their forelegs and drive their sharply pointed fore-tarsal teeth into their opponent's body. Females of Onychothrips arotrum also grasp, stab and kill with their forelegs, but they have not been observed to rear up head to head. Three of the inquiline species, Csirothrips watsoni, Thaumatothrips froggatti and Phallothrips houstoni, kill the original gall inhabitants by extending their forelegs directly in front of their bodies, tilting their heads back, remaining in this position for variable periods of time, and sharply pulling their armed fore tibiae towards the fore femora when their victim is near. Inquilinism in gall thrips may have evolved from lethal intraspecific fighting. Certain aspects of behaviour and morphology in Australian gall thrips, such as high prevalence of lethal fighting, gall ‘plugging’ in Csirothrips watsoni, attempted gall defence and apparent formation of partitions in Iotatubothrips crozieri, and the presence of wing-reduced adults in Oncothrips tepperi, indicate that these species exhibit some of the most complex behaviour thus far discovered in Thysanoptera.     

Diurnal colour change in a sexually dimorphic trait in the Andean lizard Anolis heterodermus (Squamata: Dactyloidae)

Sexual dimorphism in body size, shape and colour is widespread in lizards as well as in other taxa. In the context of sexual selection, these sex differences are commonly manifested as exaggerated male traits, which are selected by females to assess the quality of males. However, differences in sex by environment interactions can also lead to sexual dimorphism. The genus of Anolis lizards is particularly well known for sharp sexual dimorphism in dewlap colour and size; however, this is not the case in all anole species. Using digital image analyses, I assessed the existence of sexual differences in the diurnal change in colour and size of a conspicuous patch on the tail of the lizard Anolis heterodermus Duméril 1851. Results showed that the tail patch of both males and females changed in colour, but not size, from red to blue throughout the day in a similar fashion. This process took almost half a day to complete and occurred in the absence of conspecifics, suggesting that the change itself may not have an active role in social communication. However, the colour patches of males were consistently larger. The cause of the substantial variation in colour and size of the tail patch of A. heterodermus is still unknown and deserves more research. This study highlights the importance of continuous wildlife observations to identify life history traits that may be important in animal behaviour but are challenging to observe in nature.     

Spawning behaviour and sexual dimorphism in the North American cyprinid fish Notropis leedsi,the bannerfin shiner

The spawning behaviour and sexual dimorphism of the little known North American cyprinid fish, Notropis leedsi, is described based on observations made in laboratory aquaria. Notropis leedsi is a crevice spawning species, a trait characteristic of members of the subgenus Cyprinella. Males establish breeding territories through ‘mock battles’ and defend them by chasing away intruding males or, at times, through threat displays or ‘mock battles’. Although wild-caught males are significantly larger than females, sexual dimorphism is more pronounced in the colour pattern and fin size, especially the dorsal and anal fins.

The modes of spawning behaviour in the genus Notropis are reviewed. The relationship between the promiscuous mating system (polybrachygamy), the crevice spawning mode, and sexual dimorphism in N. leedsi are discussed in relation to current notions regarding sexual selection.     

A new gigantic earthworm of the genus Metaphire Sims and Easton (Megascolecidae: Oligochaeta) from Taiwan with reference to evolutional trends in body sizes and segment numbers of the Pheretima genus-group

This paper describes a new species of gigantic terrestrial earthworm Metaphire taiwanensis sp. nov. from western Taiwan. It reached the maximum length of 860 mm for a living clitellate and 637 mm after preservation. It is an autochthonous species found in Mt Beidongyan and the Meifeng area of the Central Mountain Range at elevations of 1800–2100 m. M. taiwanensis is octothecate and protandric, characters shared by Metaphire stephensoni (Michaelsen) of Indochina, and Metaphire bununa Tsai, Tsai and Liaw and Metaphire paiwanna Tsai, Tsai and Liaw of Taiwan. These four species are combined as a new species-group called the stephensoni-group within the genus Metaphire Sims and Easton. It is closely related to the congeneric ignobilis species-group, which is also octothecate but holandric. It differs from holandric and quadrithecate Metaphire magna (Chen) of Hainan Island, in which the length also reaches 700 mm. Specific variation and evolutionary trends in sizes and segment numbers of the Pheretima genus-group are discussed.     

Reproductive pattern in the southernmost populations of South American redbelly toads

Anurans can be classified as explosive or prolonged breeders. In species with short breeding periods, intensive competition for females is expected. We analyse the temporal breeding pattern of Melanophryniscus aff. montevidensis, a bufonid inhabiting grasslands of Argentina, whose breeding is concentrated in events of short duration. Males are active during more than one breeding event per season, whereas most females take part in a single event per season. Active males outnumbered females by up to 14 times at one event, operational sex ratio (OSR) ranged from 0.07 to 0.75 and intensity of sexual selection (I _s) from 0.69 to 24. We found a negative association between I _s and OSR, but no correlation between number of active males per event and OSR or I _s. The OSR is the key that regulates the intensity of sexual selection, nevertheless, and in spite of being explosive breeders, females would potentially have chances to select their mate.     

Characterisation of burrow architecture under natural conditions in the sand-dwelling wolf spider Allocosa brasiliensis

Allocosa brasiliensis (Petrunkevitch, 1910) is a wolf spider that constructs silk-lined burrows along the coastal sand dunes of Argentina, Brazil and Uruguay. This species shows a reversal in typical sex roles and sexual size dimorphism expected for spiders. Females are the smaller and mobile sex, which initiates courtship at the male burrow entrance. Mating occurs in the male burrow, and when it ends, the male leaves and the female stays inside. Females prefer to mate with those males showing longest burrows, so burrow dimensions would be under strong sexual selection pressures. Previous studies in the laboratory indicated that male burrows are longer than those of virgin females, which were described as simple silk capsules. Preliminary observations suggested that juvenile burrows presented differences from those of adults; however, detailed observations of A. brasilienisis burrow characteristics at the field were lacking. The aim of this study was to characterise the burrows of adults and juveniles of A. brasiliensis under natural conditions. We recorded the dimensions of burrows inhabited by males, females and juveniles (n = 30 for each category) and created beeswax moulds that reflected burrow shape. Juveniles inhabited tubular burrows with two branches and two openings; on the contrary, adults were found in tubular burrows with a single entry. Males and females inhabited burrows of similar length and width, but those of juveniles were shorter and narrower. We discuss the results and their possible functional explanations according to the selective pressures expected for each developmental stage and sex.     

A remarkable new species of scuttle fly (Diptera: Phoridae) whose larvae infest chickpea root nodules in India

Metopina ciceri sp. nov. is described on the basis of males with reduced wings, fully winged females, blind females with reduced wings, pupae and larvae. The larvae infest the root nodules of the chickpea, Cicer arietinum L. The blind-morph females are considered to be congeneric with the type species of the genus Typhlophorina Silvestri and this genus is synonymized with Metopina. The males, if procured in isolation, would have been assigned to a separate genus. The evolution of sexual dimorphism and dimorphic females in M. ciceri is discussed in relation to a speculative scenario involving juvenile hormone and heterochrony. It is also speculated that dispersal is undertaken by the sighted fully-winged female morph only. These speculations and the question of whether the infestation of C. arietinum by M. ciceri affects yield remains to be investigated.     

III.—Idatiella China: Two new species,with a key (Hemiptera,Miridæ)

Summary

Nine soil, freshwater, and marine species of Thecamoeba have been isolated and investigated, and nine other probably or possibly valid species were reviewed from the literature. Locomotive form/behaviour and interphase nuclear structure are adequate to distinguish all known species, and on that basis the diagnoses of several species have been clarified and questions of possible synonymy resolved.

Most known species can be placed into either a rugose or a smooth group, but it is not yet clear that the genus can be formally divided along that line.

Feeding experiments and observations on six soil and freshwater species showed interspecific differences in the kind of protozoan prey ingested. Species also differed in their rate of multiplication in culture.

One recently discovered species, T. proteoides, approaches Amoeba proteus in both morphological and cultural characteristics more than does any other known species of Thecamoeba but is clearly a member of the latter genus.     

The distribution and habitat preferences of the Afro-European species of Dynamene (Crustacea: Isopoda)

Summary

The geographical distribution of the genus Dynamene is described in the light of the recent discovery of three new species. D. bidentata appears to have a Boreal distribution whilst that of D. edwardsi and D. magnitorata is Atlanto-Mediterranean. D. torelliae, D. bifida, and D. tubicauda have a Mediterranean distribution but the first species may extend into the Black Sea. Only one species, D. ramuscula, has been recorded outside the Afro-European region, in S.E. Australia. The ranges and habitat preferences of those species outside the Mediterranean overlap as do some of those within the Mediterranean, particularly in the Naples Bay region. Juveniles of D. bidentata inhabit and feed on intertidal algae while adults shelter in crevices and empty tests of Balanus perforatus, mainly below MTL. Settlement of males into barnacle tests appears to be random, but females show some degree of aggregation, perhaps to other females. Other species show the same change of habitat at sexual maturity and all inhabit intertidal or inshore localities.     

Intersex in the gonochoristic crustacean Tanais dulongii (Audouin, 1826) (Peracarida: Tanaidacea: Tanaididae): a comparison of external reproductive characteristics

Tanais dulongii (Audouin, 1826) is a small benthic crustacean with separate sexes and a marked sexual dimorphism characterized by a cephalothorax narrowed anteriorly, larger chelae (claws) and a pair of tiny genital cones in males, and ovisacs that form chambers for carrying embryos in females. Recent studies have described the existence of intersexual individuals with a cephalothorax similar to males, large chelae and ovisacs, but, due to their small size, it has not been possible to confirm the presence of genital cones under normal light microscopy. The present study analyses and compares external reproductive structures under scanning electron microscopy, of male and female T. dulongii, to corroborate the presence of both ovisacs and genital cones in potentially intersex individuals. The possible causes, such as hermaphroditism, environmental sex determination, parasitism, genetic aberration or endocrine-disrupting pollutants, are discussed.     

Further morphological and molecular studies of driftwood hoppers (Crustacea: Amphipoda: Talitridae) from Mediterranean/north-east Atlantic coastlines

An unknown talitrid was discovered in 2011 in the Swale, UK, living in driftwood. Sequencing of multiple mitochondrial and nuclear genes (cytochrome oxidase I, 18S rDNA and 28S rDNA) confirms that the unknown taxon was close to Orchestia mediterranea A. Costa 1857. The driftwood in which it was found was of Douglas fir (Pseudotsuga menziesii), probably imported from North America. Relative growth methods allow us to reject the null hypothesis that the unknown taxon was a juvenile Orchestia mediterranea. This is because the unknown taxon initiates sexual maturation at an earlier moult number (neoteny) and is predicted to reach terminal moult stages at a much smaller size (dwarfism) than its closest relative O. mediterranea. Both molecular and morphological data confirm that the unknown taxon from the Swale, UK, is a new driftwood specialist taxon, distantly related to the driftwood specialist genus Macarorchestia. Additional data for body length and sex ratios are presented for Macarorchestia. In addition, relative growth methods have shown that the driftwood species Orchestia microphtalma Amanieu and Salvat 1964 is closer to the genus Macarorchestia rather than to the wrack generalist one, Orchestia. This evidence is in line with the molecular results that do not cluster morphologically defined species of Orchestia monophyletically.     

Foraging behaviour of three sphaerodactylin geckos on Trinidad and Tobago (Sauria: Gekkonomorpha: Sphaerodactylini: Gonatodes)

Taxonomic families of insectivorous lizards are usually characterized by one of two distinct foraging modes, namely ambush ‘sit-and-wait’ or active ‘widely foraging’. In the Gekkonomorpha the situation has been unclear and in dispute, and among these, that in the Sphaerodactylini is almost unreported. We, therefore, examined the foraging mode of three sphaerodactylin species on Trinidad and Tobago, in May—June 2000 (totalling 72 individuals, observations averaging 23.6 min/individual). In terms of species averages, Gonatodes vittatus, G. humeralis and G. ocellatus all moved for only 1.6–3.55% of observation time (PTM, percent time moving), and switched from sitting to locomoting only 0.18–0.36 times per minute (MPM, moves per minute). The genus thus is a strict sit-and-wait forager. In G. vittatus, the foraging mode was unaffected by sex or habitat structure. In all three species, foraging mode was unaffected by the time of day or air temperature. In G. humeralis, foraging activity (PTM or MPM) correlated with light intensity in the forest within a population (at least MPM) and among populations (at least PTM). Among the three species, too, foraging activity (PTM and MPM) ranked with light intensity during sampling. In all three species, the geckos perched for 68–76% of the time (at any height) with the head pointing down, apparently so as to see better. In conclusion, the three species are strict sit-and-wait' visual hunters that are dependent on light.     

A review of Paranannopidae (Copepoda: Harpacticoida) with claviform aesthetascs on oral appendages

Leptotachidia iberica Becker is completely redescribed from the type material and is shown to carry claviform aesthetascs on the mouthparts. This is regarded as a character of high phylogenetic significance and, together with the loss of the mandibular exopod and the form of sexual dimorphism of the distal segment of the male P2 endopod, provides overwhelming evidence for a common ancestry for the genera Leptotachidia, Micropsammis Mielke and Paradanielssenia Soyer. Additional observations are made of the morphology of M. noodti Mielke, M. secunda Mielke and P. biclavata Gee. From a discussion of the probable relationships within this group of genera it is concluded that M. secunda is the most likely sister group of Leptotachidia and therefore must be removed to a new genus Telopsammis gen. nov. New diagnoses are given for all the genera.     

First-instar morphology and sexual dimorphism in the gall-inducing scale insect Apiomorpha Rubsaamen (Hemiptera: Coccoidea: Eriococcidae)

Sexual dimorphism among crawlers of the scale insect family Eriococcidae is reported for the first time. The general morphology of crawlers of the gall-inducing genus Apiomorpha (Eriococcidae) is presented and sexual dimorphism described. Sexual dimorphism appears to be associated with differential dispersal and settling-site preference of the sexes during the crawler stage. First-instar males of the A. pharetrata and A. munita species-groups settle only on the galls induced by their mothers or, in the case of A. munita, also galls of nearby females, whereas female crawlers disperse. Female crawlers of all species of Apiomorpha, and male crawlers of most species, are well suited for air-borne dispersal. It is suggested that sexual dimorphism among crawlers of Apiomorpha, and some other scale insects, is the result of loss or reduction of those morphological features associated with dispersal. In addition, male crawlers of some species of Apiomorpha have sensory structures which may assist in the detection of sex-specific settling sites.     

A re-assessment of the genera Holorusia Loew (=Ctenacroscelis Enderlein), Ischnotoma Skuse and Zelandotipula Alexander (Diptera: Tipulidae), with notes on their phylogeny and zoogeography

Summary

A short historical background to the genera considered is given. A review is made of a number of characters which had previously only been treated inconsistently, or not at all. As a result, the old-world genus Ctenacroscelis is merged with Holorusia sensu stricto, as represented by the isolated Californian type-species. All other species previously referred to Holorusia sensu lato are redistributed to two genera; the tropical South American and New Zealand forms are united into Zelandotipula; the Chilean element and the Australian species are united into Ischnotoma, the name Icriomastax Enderlein being resurrected as a subgenus to receive most of the Chilean species.

Tentative phylogenetic and zoogeographic observations are made. Holorusia and Ischnotoma are considered and discussed as sister-groups, whilst Zelandotipula is believed to be only distantly related. Zoogeographically Holorusia is seen as a successful Asiatic genus; Ischnotoma as a receding group, with extreme southern-continental distribution, having had a much wider distribution as indicated by the European Oligocene fossil Holorusia vasifera, transferred here to Ischnotoma. Zelandotipula is viewed as an essentially Neotropical genus, which has made one ‘invasion’ of New Zealand, probably in the geologically recent past.

Résumés of the principal features of the re-defined genera are given, together with systematic notes on certain species, and species catalogues giving distributions and all new name combinations.     

A new species of Fabricinuda Fitzhugh, 1990 (Fabriciinae: Sabellidae: Polychaeta) from the Caribbean,with an emendation of the genus

During a survey of the infauna of seagrass meadows in Venezuela, several specimens of an unknown species of Fabriciinae were collected. The species could not be assigned to any genus of the subfamily, although it was most closely allied to Fabricinuda Fitzhugh, 1990. However, the absence of pseudospatulate inferior notochaetae on chaetiger 8 prevented assignment of the specimens to this genus since their presence on chaetigers 3 to 8 is one of its diagnostic apomorphies. In order to decide whether to establish a new genus for the species or to redefine Fabricinuda, a phylogenetic analysis of the subfamily was made on the basis of a pre‐existing character matrix. Twenty‐two anatomical characters were analysed for 59 species including the new one, and from the resulting consensus tree it was clear that the new species must be included within Fabricinuda and consequently an emendation of the genus is provided herein.