Elsevier

Biological Conservation

Volume 101, Issue 1, September 2001, Pages 9-13
Biological Conservation

The species status of Cathormiocerus britannicus, an endemic, endangered British Weevil

https://doi.org/10.1016/S0006-3207(01)00048-9Get rights and content

Abstract

This study uses DNA sequence and morphometric comparisons to investigate the systematic status of a broad-nosed weevil, Cathormiocerus brittanicus (Curculionidae; Entiminae), currently described as an endangered UK endemic. The nuclear marker ITS2 was sequenced from specimens of C. brittanicus, C. myrmecophilus, C. curvipes and C. maritimus. Little sequence differentiation was detected between C. brittanicus and C. myrmecophilus, although both species' sequences were different to those of the other two congeners under study. Multivariate analyses of eight morphometric characters also failed to distinguish C. brittanicus from C. myrmecophilus. The taxonomic status of the two species is therefore questionable. If they are the same species the endangered status of C. brittanicus shall need re-assessing and, because C. myrmecophilus also occurs in France, so will its status as a UK endemic.

Introduction

The broad-nosed weevil genus Cathormiocerus (Curculionidae; Entiminae) is small, but zoogeographically interesting as it is restricted to the extreme west of the Palaearctic region (Morris, 1997). Of the 70 species in total only 10 are found outside the Iberian peninsula or Morocco (de la Escalera, 1918). Ten species have been reported from France (Tempére and Péricart, 1989) and five species are known from the British Isles (Morris, 1997).

The biology of the genus is very poorly known, but its species are believed to be similar in many respects to those in the related genus Trachyphloeus. Trachyphloeus species overwinter as adults (Hoffman, 1950, Hansen, 1965, Dieckmann, 1980, Borovec, 1989), and may be found around the roots of the host plants where they are believed to feed on fresh and partly decomposed plant material (Dieckmann, 1980). Cathormiocerus species are believed to be polyphagous and are to be found around the base of such plants as Plantago and Thymus spp. (Morris, 1997). The elytra are fused suggesting that their dispersal ability is poor, as is the case in Trachyphloeus species (Jermin and Mahler, 1993).

All Cathormiocerus species exhibit a form of parthenogenesis termed ploidy stasis (Lamb and Wiley, 1986). The causative agent of parthenogenesis in Cathormiocerus weevils is unclear. In the Aramigus tessellatus complex (Curculionidae, Naupactini) parthenogenesis is probably caused by polyploidy (Normark, 1996). The bacteria Wolbachia has been found in parthenogenetic insects. In these insects it has been shown to be the cause of parthenogenesis and also involved in parasite resistance (Hsiao & Hsiao, 1985a, Hsiao & Hsiao, 1985b, Stouthammer et al., 1990, Hsaio, 1996).

Cathormiocerus species are normally found in marginal habitats of relatively low diversity and it has been suggested that the superior colonising ability of parthenogenetic species enables them to monopolise appropriate niches in such habitats (Lanteri and Normark, 1995).

Cathormiocerus britannicusBlair, 1934 is currently listed as endemic to the UK (Morris, 1997), is described as endangered (Hyman and Parsons, 1992) and has its own Species Action Plan (UK Biodiversity Steering Group, 1999). C. brittanicus is very similar to Cathormicenus myrmecophilus Seidlitz and the species are presently separated on morphological grounds, namely, differences in the elytra, striae and the rostrum. In the UK both species are confined to coastal habitats in the Southern England where they are to be found in short, stony turf (Morris, 1997). C. myrmecophilus also occurs in continental Europe (in Normandy, Brittany and south into the Iberian peninsula; Hoffman, 1950).

Taxonomic rank is a very important criterion in assessing the conservation priority of an endangered organism. Because of the close similarity between C. britannicus and C. myrmecophilus and the complications generated by parthenogenesis and, potentially, by Wolbachia infection the taxonomic status of the putative UK endemic is unclear. This study is an investigation of the species status of C. britannicus using DNA sequencing and morphometric analysis.

Section snippets

Specimen collection and identification

Specimens of Cathormiocerus myrmecophilus, C. britannicus and C. maritimus, were collected with a suction sampler from short turf at known localities on England's south coast (Fig. 1). Very few sites are known for these species and they are all in England's southern counties. Collections were made between 21 and 28 May 1999. Cathormiocenus curvipes was collected by searching beneath stones and plants in the Oriental Pyrenees, southern France (Grid Ref: 113427) on 3rd February 2000. Individuals

Results

Table 1 shows pair-wise Kimura two-parameter distances for all the pairs of the 13 ITS2 sequences. Approximately 670 bp of the ITS2 region were sequenced. One specimen for each of the britannicus sites was sequenced. Three specimens for the Sussex C. myrmecophilus and two specimens for the Devon C. mymecophilus were sequenced. The two sequenced specimens of C. maritimus came from the same Cornwall location. The two sequenced C. curvipes specimens came from the same location in the oriental

Discussion

Neither the molecular or the morphometric analyses described here provide any evidence to support the species separation of C. brittanicus and C. myrmecophilus. On the basis of the multivariate analysis of the morphometrical data it is impossible to define C. britannicus as a species. The morphological variables that are used to separate C. myrmecophilus and C. britannicus are all of the continuous type therefore variation is expected to be apparent in these variables within, as well as between

Acknowledgements

I must convey my appreciation to Mike Shanahan, Cathy Walton, Roger Key and two anonymous referees for perusal of manuscripts. Many thanks to Peter Hodge for collection of specimens. This study was funded by English Nature.

References (27)

  • J.C. Avise

    A role for molecular genetics in the recognition and conservation of endangered species

    Trends in Ecology and Evolution

    (1989)
  • C. Hsiao et al.

    Rickettsia as the cause of cytoplasmic incompatibility in the alfalfa weevil Hypera postica (Gyllenhall)

    Journal of Invertebrate Pathology

    (1985)
  • J.C. Avise et al.

    Molecular genetic relationships of the extinct dusky seaside sparrow

    Science

    (1989)
  • K.G. Blair

    A new species of Cathormiocerus from Britain

    Entomologists Monthly Magazine

    (1934)
  • Borovec, R., 1989. Les espèces Françaises du genre Trachyphloeus Germar, 1824. In Tempère, G. (Ed.) 81, pp.157....
  • M.M. de la Escalera

    Revision de las especies del genreCathormiocerus Schoenherr. de la Peninsula y Marruecos

    Trabajos del Museo Nacional de Ciencias Naturales Madrid (Serie Zoologia)

    (1918)
  • L. Dieckmann

    Beitrage zur insekten fauna der DDRColeoptera — Curculionidae (Brachycerinae, Otiorryhnchinae, Brachyderinae)

    Beiträge zur Entomologie

    (1980)
  • Hansen, V., 1965. Danmarks Fauna. Snudebiller...
  • T.H. Hsiao et al.

    Hybridisation and cytoplasmic incompatibility among alfalfa weevil strains

    Entomologia Experimentalis et Applicata

    (1985)
  • Hsaio, T.H. 1996. Studies of interactions between alfalfa weevil strains, Wolbachia endosymbionts and pasrasitoids. In...
  • Hoffman, A., 1950. Faune de France. Coléoptères Curculionides. Première Partie. Vol,...
  • J.N. Hogue et al.

    Morphological variation in adult aquatic insects-associations with developmental temperature and seasonal growth patterns

    Journal of the North American Benthological Society

    (1991)
  • Hyman, P.S. and revised and updated by Parsons, M.S., 1992. A Review of the Scarce and Threatened Coleoptera of Great...
  • View full text