Published December 31, 2010 | Version v1
Taxonomic treatment Open

Truncaudum impexum Schedl, comb. n.

Creators

Description

Truncaudum impexum (Schedl), comb. n.

Xyleborus impexus Schedl, 1942c

Xyleborus dentatulus Browne, 1981 syn. n. Xyleborus circumspinosus Schedl, 1972b, syn. n. Xyleborus falcarius Schedl 1942c, syn. n.

Xyleborus subdentatulus Browne, 1986 syn. n. Xyleborus vernaculus Schedl, 1975b, syn. n. Xyleborus putputensis Browne, 1986, syn. n.

Specimens examined. T. impexum: New Guinea (holotype, NHMW); New Guinea (2, BHJ); New Guinea (FICB); New Guinea, Madang Prov. (8, Hulcr det., MSUC), Oro Prov. (30, Hulcr det., MSUC), West Sepik (4, Hulcr det., MSUC). X. dentatulus: New Guinea, New Ireland, Kamdaru (holotype, BMNH); Takehara coll. 1975.; New Guinea, Morobe Province, Bulolo (3, Hulcr det., FICB); New Guinea, Madang Prov. (225, Hulcr det., MSUC), West Sepik (3, Hulcr det., MSUC). X. circumspinosus: New Guinea, Morobe Province, Bulolo (1, Schedl det., MSUC); New Guinea, Morobe, Umboi (paratype, NHMW). X. subdentatulus: New Guinea (holotype, BMNH). X. falcarius: New Guinea (holotype, NHMW). X. vernaculus: New Guinea, Manus island, Nuvok (holotype, NHMW). X. putputensis: New Guinea, New Britain (holotype, BMNH).

Comments. T. impexum has a very characteristic abruptly truncated elytra, with the declivity surrounded by conspicuous serrate costa. Serrations on the costa are extraordinarily variable and often different between the lower and the upper margin of the declivity. This variation is not correlated with genetic distance between individuals.. A preliminary analysis of intraspecific DNA sequence variation suggests that T. impexus morphotypes with different declivities belong to a single lineage. 28S rDNA sequence divergence (p-distance) of two very different morphotypes does not exceed 0.1%, while p-distances to T. longior and T. agnatum is 0.008 and 0.005, respectively. Differences between sequences of CO1 mtDNA are larger (randomly chosen variants of T. impexum) between 0.109 and 0.116 (nearly all substitution in 3rd codon sites), but much lower than average between-species difference among Truncaudum spp. (average p-distance = 0.147, never below 0.130) (data from Cognato et al., 2011).

Holotype of X. dentatulus Browne is virtually identical to that of T. impexum, only the serrations on the upper edge of declivity are slightly smaller. The declivity in X. subdentatulus has tubercles larger than in most T. impexum, but not exceedingly large, and in homologous positions. X. falcarius was described based on a single difference, a tooth on first interstria on declivital apex (Schedl, 1942c). X. vernaculus was described as different from X. falcarius (syn. with T. impexum here) by its gradually decreasing size of teeth on upper declivital margin (Schedl, 1975b). The actual difference in teeth size is minor, fully within the variation in T. impexum. Holotype of X. putputensis is a male of Truncaudum impexum.

Notes

Published as part of Hulcr, Jiri, 2010, New genera of Palaeotropical Xyleborini (Coleoptera: Curculionidae: Scolytinae) based on congruence between morphological and molecular characters, pp. 1-33 in Zootaxa 2717 on page 26, DOI: 10.5281/zenodo.199742

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Linked records

Additional details

Biodiversity

Family
Curculionidae
Genus
Truncaudum
Kingdom
Animalia
Order
Coleoptera
Phylum
Arthropoda
Scientific name authorship
Schedl
Species
impexum
Taxonomic status
comb. nov.
Taxon rank
species

References

  • Schedl, K. E. (1942 c) Interessante und neue Scolytiden und Platypodiden aus der australischen Region. 79 Beitrag. Mitteilungen der Munchener Entomologische Gesellschaft, 32, 162 - 201.
  • Browne, F. G. (1981) Bark beetles and ambrosia beetles (Coleoptera, Scolytidae and Platypodidae) intercepted at Japanese ports, with descriptions of new species, V. Kontyu, 49, 125 - 136.
  • Schedl, K. E. (1972 b) New Scolytidae and Platypodidae from the Papuan subregion and New Caledonia, I. 271 Beitrag. Papua New Guinea Agricultural Journal, 23, 49 - 60.
  • Browne, F. G. (1986) Bark beetles and ambrosia beetles (Coleoptera, Scolytidae and Platypodidae) intercepted at Japanese ports, with descriptions of new species, XIII. Kontyu, 54, 89 - 99.
  • Schedl, K. E. (1975) New Scolytidae and Platypodidae from Papua and New Guinea, IV. 317. Contribution to the Morphology and Taxonomy of the Scolytoidea. Annalen des Naturhistorischen Museums in Wien, 79, 337 - 399.
  • Cognato, A. I., Hulcr, J., Dole, S. A. & Jordal, B. H. (2011) Phylogeny of haplo-diploid, fungus-growing ambrosia beetles (Coleoptera: Curculionidae: Scolytinae: Xyleborini) inferred from molecular and morphological data., Zoologica Scripta, in press.