Note on the life history of the magpie moth,Nyctemera annulata (Lepidoptera: Arctiidae)

Nyctemera annulata Boisduval was reared in the laboratory at 26±1°C and 50 ±5% RH on a host plant, ragwort (Senecio jacoboea L.), and on an artificial diet. On ragwort the average life cycle of 34 days embraced a larval period of 24 days, with up to 6 larval instars, and a pupal period of 9–11 days, depending on whether pupation occurred at the 5th or 6th instar. On the artificial diet the larval period of 56 days, involving up to 10 instars, was followed by a pupal period of 9 days, for an average life cycle of 65 days.     

Type materials of the species of the Planorbidae (Mollusca,Gastropoda, Hygrophila) described by Shuichi Mori

ABSTRACT

The planorbid species that were described by Shuichi (Syuiti) Mori from Japan have long been enigmatic and their taxonomy has been highly confused. This situation is also an impediment to action for the conservation of Japanese planorbids which are one of the most threatened freshwater snail groups in the country. Based on our examination of Shuichi Mori’s collection stored in the Kyoto University Museum, type materials of the taxa described by him are re-illustrated and re-examined for the first time. Our examination suggested that Gyraulus amplificatus (Mori, 1938) is not a morphological form of Gyraulus biwaensis but a distinct species. Gyraulus pulcher (Mori, 1938) can be regarded as a junior synonym of Gyraulus chinensis.     

Taxonomic revision of the land snail genera Macrochlamys Gray, 1847 and Sarika Godwin-Austen, 1907 (Eupulmonata: Ariophantidae) from south-eastern Myanmar,with descriptions of three new species

ABSTRACT

Knowledge of Myanmar land snails is based on the late eighteenth to early twentieth century literature and many species need to be re-investigated, especially in the genera Macrochlamys Gray, 1847 and Sarika Godwin-Austen, 1907. In order to update this knowledge, this paper presents information on these two related genera based on new materials from south-eastern Myanmar. Fifteen species are recognised in the south-east of Myanmar. Of these, live material was available for eight Macrochlamys and Sarika species and these are described in full herein, based on data from the shell, external morphology and genitalia, including three species new to science (M. brachystia n. sp., S. concavata n. sp. and S. lopa n. sp.) and five species redescribed (M. aspides, M. kelantanensis, M. petasus, S. consepta and S. obesior). The remaining five species are known only from their shell morphology (M. cauisa, M. perpaula, M. poongee, M. salwinensis and S. birmana) and two species are known from genitalia (S. dugasti and S. resplendens). For these species the shells are figured and some taxonomic remarks are provided.

http://www.zoobank.org/urn:lsid:zoobank.org:pub:58D2A9E7-50FD-49C2-B2F4-4D00457EA331     

Genital system development of Williamia radiata (Gastropoda, Siphonariidae)

The adult anatomy and development of the genital system of the limpet Williamia radiata (Siphonariidae, Gastropoda) was investigated by means of 3D computer reconstruction and visualization of serial resin and paraplast light microscopical sections. As is characteristic for siphonariid species, the adult genital system consists of a single duct, the spermoviduct leading from the nidamental glandular system to the anteriorly located genital atrium with opening. The copulatory complex as well as the bursa copulatrix also open into the common genital atrium. The genital system develops from three separate anlagen. The posterior one appears first at a body length of 0.7 mm and gives rise to the ovotestis and part of the hermaphrodite duct. The nidamental glandular complex, the fertilization pouch-spermatheca complex, part of the hermaphrodite duct, the posterior part of the spermoviduct, and the bursa copulatrix develop later from the pallial anlage. Finally, the anterior anlage is formed on the right side of the head and gives rise to the genital atrium, the copulatory complex, and the anterior spermoviduct. This formation of the genital system from three, locally separated anlagen, differs strikingly from that of most other species of the Euthyneura. In both the Nudibranchia (Opisthobranchia) and the Stylommatophora (Pulmonata) development proceeds from a single site. We regarded this as a secondary condition as a result of derived features like heterochronies in development in these taxa. Comparison of development with that of other species of the Pulmonata allows conclusions on homology. The homology of the bursa copulatrix within the pulmonates is confirmed. The two separate chambers inside the spermoviduct of W. radiata correspond to oviduct and vas deferens of the freshwater Basommatophora.     

Ecological diversity and speciation in land snails of the genus Mandarina from the Bonin Islands

 Endemic land snails of the genus Mandarina of the oceanic Bonin Islands offer an example of habitat and character divergence among closely related species. The molecular phylogenies of Mandarina show that a divergence of arboreal, semiarboreal, and ground-dwelling species has occurred repeatedly in different times, areas, and lineages. Ecological diversification is suggested to be important for the coexistence of Mandarina species based on the facts that sympatric species are typically highly differentiated ecologically and morphologically, and that species occupying similar habitats do not coexist. The ecological diversification of Mandarina has occurred without much genetic divergence compared with that of its mainland relatives. This suggests that morphological and ecological diversifications are accelerated in depauperate environments where there are fewer competitors and predators. Although the details of the reproductive isolation mechanisms are not understood and further examination is needed, the rapid evolution of prezygotic isolation is the main cause of speciation in Mandarina. In particular, ecological diversification may be an effective barrier to gene exchange between two species. Because of incomplete postmating isolation and the lower genetic divergence among species of Mandarina, breakdowns of reproductive isolation have frequently occurred as a result of habitat change. It is important to estimate the effect of hybridization on species diversification in future studies. Received: February 7, 2002 / Accepted: October 22, 2002 Acknowledgments I express my sincere thanks to A. Davison, B.C. Clarke, A. Guiller, D. Thomaz, K. Tomiyama, I. Hayami, and K. Tanabe for helpful advice and assistance. This study was supported by grants from the Japan Society for the Promotion of Science and the Nippon Life Insurance Foundation.     

Radiation of the land snail genus Sagda (Pulmonata: Sagdidae): comparative morphology, biogeography and ecology of the species of north-central Jamaica

The radiation of the endemic Jamaican land snail genus Sagda is examined through analysis of the comparative shell morphology, anatomy, ecology and biogeography of the four species inhabiting north-central Jamaica: S. centralis sp. nov. , S. spei, S. bondi and S. montegoensis. The species are all rather similar in their morphology and ecology. The shells show some differences in the presence or absence of internal lamellae, the position of the lamellae, the form of the depression in the centre of the base, the regularity of sculpture (low ribs) and the pattern of microsculpture. Slight differences in the form of the radular teeth are found between some species. The structure of the secondary ureter is peculiar: in all species it is open shortly behind the mantle collar, then branches into two closed tubes which open separately on the outside of the mantle collar. Despite its great complexity, the reproductive system is rather uniform among species; differences are seen in the number of pockets that form spines on the spermatophore. The complex, three-branched spermatophore is formed within the entire epiphallar branch of the penis, whereas the appendicular branch apparently assumes the copulatory function. When inactive, all species are found associated with rocks or, less commonly, among leaf litter. Activity occurs primarily at night and mostly on leaf litter rather than rocks. The snails eat dead plant material, including a variety of plant species. All species (with the possible exception of S. montegoensis) are ovoviviparous. They overlap broadly in the range of climates occupied. The geographic ranges of the four species are overlapping, although Sagda bondi has a parapatric distribution in relation to the western species S. grandis. Fossil and subfossil evidence shows that shifts in the ranges of the species have occurred in the late Quaternary; Pleistocene-Holocene environmental changes, habitat destruction by man, and possibly other environmental changes during historical times are probably involved. Radiations of other land snail groups on tropical islands have generally produced greater morphological and ecological differentiation than in Sagda. Allopatric or parapatric species distributions appear to be more common in other land snail radiations.     

Biogeography of the Helicoidea (Mollusca: Gastropoda: Pulmonata): land snails with a Pangean distribution

The biogeography of helicoid land snails was investigated using cladistic methods. Parsimony analysis under Assumption 0 yielded twelve area cladograms (length=25, c.i.=0.76, r.i.=0.86). The pattern of vicariance for the Helicoidea indicated that families originated with the break up of eastern Gondwana and Laurasia between the late Mesozoic and mid-Tertiary, and possible vicariance events are identified. It is proposed that Asian terranes, located between India and Australia, maintained contact with northern Australia until the late Cretaceous, which is later than is suggested in current palaeogeographical hypotheses.