Helgen, Kristofer Michael. "A reassessment of taxonomic diversity and geographic patterning in the Melanesian mammal fauna." Thesis, 2007. http://hdl.handle.net/2440/61970.
Анотація:
Comprehensive morphology-based taxonomic revisions are presented for four
mammal genera endemic to the Australo-Papuan region. These include Pseudohydromys
Rummler, 1934 and Mallomys Thomas, 1898, small- and large-bodied rodent genera,
respectively, endemic to montane areas on mainland New Guinea; the marsupial genus
Spilocuscus Gray, 1862, distributed throughout lowland areas of mainland New Guinea,
on most adjacent island groups, and in tropical northern Australia; and Pteralopex
Thomas, 1888, a genus of large-bodied fruit-bats endemic to the Solomon and Fijian
Archipelagos of outer Melanesia.
Museum specimens of “moss-mice” traditionally classified in the genera
Pseudohydromys, Microhydromys Tate and Archbold, 1941, Neohydromys Laurie, 1952,
and Mayermys Laurie and Hill, 1954 are here referred to three generic-level lineages,
Pseudohydromys (11 species), Microhydromys (one recognized species), and Mirzamys
new genus (for two newly-described species). The 11 species of Pseudohydromys
recognized here include six that are newly described. Much of this newly-characterized
biological diversity is sympatric diversity. For example, samples attributed in the past to
Pseudohydromys murinus Rummler, 1934 include two species, P. berniceae n. sp. and P.
eleanorae n. sp., which have been collected syntopically with true P. murinus. Likewise,
samples attributed in the past to Pseudohydromys occidentalis Tate, 1951 are also shown
to represent a number of “cryptic” lineages sympatric with true P. occidentalis, including
P. patriciae n. sp. and Mirzamys louiseae n. sp., as well as an additional overlooked
allopatric taxon, Mirzamys norahae n. sp.
Within Mallomys, the nature and extent of sympatric interactions between the
giant-rats M. rothschildi Thomas, 1898, M. aroaensis (De Vis, 1907), and M. istapantap
Flannery, Aplin, and Groves, 1989 are reviewed and clarified. Subspecific boundaries
within M. rothschildi are re-assessed, and in total seven species of Mallomys are
recognized, including M. hercules Thomas, 1912, an allospecies endemic to the outlying
mountain ranges of the Huon Peninsula, and two newly-described species from other outlying mountain blocks (the Arfak Mountains of western New Guinea and Mt. Bosavi
in south-central New Guinea).
The spotted cuscuses, genus Spilocuscus, are difficult to classify at species-level
because most taxa in the genus are distributed allopatrically or parapatrically. A
minimum of seven geographic “morphs” can be recognized in the genus on the basis of
size and pelage characters. The oldest name in the genus, S. maculatus, is shown to refer
to dark-spotted cuscuses from the Moluccas and southern New Guinea, not to the orange
and white cuscuses from northern New Guinea, as traditionally applied. A review of
craniometric and qualitative morphological traits confirms that each of these “morphs”
(as delineated by external morphology) is characterized by other distinctive
morphological attributes; this fact and the lack of evidence for introgression between any
of these various taxa is used to argue that most of these seven morphologically-distinctive
lineages should be recognized as distinct allospecies. Only two taxa in the genus co-occur
sympatrically—the large-bodied, black-saddled/spotted taxon S. rufoniger and a smaller,
orange and white species, both of which are shown to be widely distributed in both
northern and western New Guinea. No scientific name is available for the latter taxon,
which is newly designated as Spilocuscus tardus n. sp.
Taxa traditionally classified in Pteralopex are referred here to two distinct genera,
Pteralopex, comprising only those species endemic to the Solomon Archipelago, and
Mirimiri Helgen, 2005, for the monotypic Fijian representative M. acrodonta (Hill and
Beckon, 1978). Five species of Pteralopex are recognized in total. Museum specimens
traditionally identified as “Pteralopex anceps” are shown to represent two sympatric
species, P. anceps Andersen, 1909 and P. flanneryi Helgen, 2005 (the largest species in
the genus), both of which are endemic to islands in the north-eastern Solomon Islands
that were once part of a larger Pleistocene landmass; insular co-occurrence of P. atrata
Thomas, 1888 and the recently-described P. taki Parnaby, 2002 on New Georgia is also
newly documented.
Each of these revisions highlights sympatric interactions and substantial
undiagnosed biological diversity overlooked by previous reviewers, and illuminates
intraregional biogeographic boundaries more accurately as a result. Before I began this
study four years ago, a total of 17 mammal species were formally recognized within the genera Pseudohydromys, Neohydromys, Mayermys, Microhydromys, Mallomys,
Spilocuscus, and Pteralopex (Flannery 1995a, 1995b). This thesis defends the recognition
of 33 species within those same generic lineages, which suggests that the magnitude of
biological diversity across the Melanesian mammal fauna could well be underestimated
by fully one-half. Preliminary results reflecting complementary discoveries of overlooked
sympatric diversity in other Melanesian mammal genera (Uromys, Microperoryctes,
Myoictis, Pteropus, Nyctimene, Leptomys, and others) are also briefly discussed. Similar
comprehensive reviews, analysing morphometric attributes and qualitative anatomical
characters of all available museum specimens, are still needed for all remaining
Melanesian mammal genera before any reasonable holistic portrayal of community
ecology and historical biogeography can be developed for the Melanesian mammal fauna
as a whole.
Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2007