Thursday, February 22, 2018

[Mammalogy • 2018] Molossus fentoni • A New Species of Mastiff Bat (Chiroptera, Molossidae, Molossus) from Guyana and Ecuador

Molossus fentoni
Loureiro, Lim & Engstrom, 2018

We describe a new species of mastiff bat in the genus Molossus (Molossidae), which was previously confused with the common and widely distributed M. molossus, from Guyana and Ecuador based on morphological and molecular differences. It is diagnosed by the following set of morphological characteristics: bicolored dorsal pelage, rounded anterior arch of the atlas, triangular occipital bone, and smaller body and skull size. In a molecular phylogenetic analysis of mitochondrial and nuclear DNA, maximum likelihood and parsimony trees recovered eight clades in the genus and a polyphyletic relationship for the M. molossus species complex. The new species was recovered in a well-supported clade that can be genetically distinguished from other species in the genus by its high level of sequence divergence based on the mitochondrial CO1 gene (8.0–10.1%) and on the nuclear gene beta fibrinogen (1.0–3.1%). It is broadly sympatric with M. molossus sensu stricto in northern South America, but morphologically distinct and genetically divergent.

 Keywords: Molossidae, New species, Phylogenetics, South America, Taxonomy

Fig. 5. Holotype of Molossus fentoni sp. nov. (ROM 122583). Adult male with a medium brown dorsal pelage.

Fig. 4. Dorsal, ventral, posterior, and lateral views of the skull of the holotype of Molossus fentoni sp. nov.

Molossus fentoni sp. nov. 

Diagnosis: A set of traits distinguishes Molossus fentoni from other Molossus. In M. fentoni the infra-orbital foramen is laterally directed; the basioccipital pits are rounded and of moderate depth; the occipital is triangular in posterior view; the upper incisors are thin and long with parallel tips and project forward in an oblique plane relative to the anterior face of the canines (Fig. 4); and the anterior arch of the atlas is rounded (Fig. 6).

Distribution: Molossus fentoni is currently known from the administrative regions of Potaro-Siparuni and Upper Takutu-Upper Essequibo in Guyana and in Orellana province in Ecuador. Although, it has not been documented in the intervening 2000 km of lowland Amazonian forest, we anticipate that it will be found to have a broader distribution then initially represented in our collections. One individual of M. fentoni was collected in syntopy with M. coibensis, M. m. molossus, and M. rufus at ... east of Pompeya Sur, Orellana, Ecuador on 18 May, 2006.

Etymology: This species is named in honour of M. Brock Fenton, Professor Emeritus, Western University, London, Ontario, and one of the world’s foremost researchers in bat ecology and behaviour. He was born in Guyana to Canadian parents and conducted fieldwork in the country in 1970.

Taxonomic remarks: Husson (1962) designated the lectotype of M. molossus as the larger of the two bats described by Buffon and Daubenton (1763). Later, Husson (1962) restricted the type locality of M. molossus to Martinique, which previously had only been designated as the Americas in the first citation of this specimen (Buffon and Daubenton, 1759). Specimens of M. molossus from Martinique were morphologically analyzed in our study and have all the characteristics described above for M. molossus, and not for M. fentoni. In addition, the DNA sample of M. molossus from Martinique clustered with several other samples of M. molossus from the mainland in the phylogenetic trees (Fig. 2), such as Guyana, Suriname, and Brazil, corroborating its affiliation with M. molossus and the distinction from M. fentoni.

Fig. 8. Schematic comparison of cranial features in Molossus.
A and B – Posterior view; C and D – frontal view; E and F – Ventral view. Numbers represent characters described in the text. 1 – Lambdoidal crest and occipital complex; 2 – Sagittal crest; 3 – Mastoid process; 4 – Infra-orbital foramen; 5 – Upper incisors; 6 – Rostrum shape; 7 – Basioccipital pits.

 Livia O. Loureiro, Burton K. Lim and Mark D. Engstrom. 2018. A New Species of Mastiff Bat (Chiroptera, Molossidae, Molossus) from Guyana and Ecuador. Mammalian Biology. 90; 10-21.  DOI: 10.1016/j.mambio.2018.01.008