Molossus pretiosus is a molossid bat that has been thought to exist in Honduras. While some authors have suggested its range extends all the way to Mexico, others have placed its northernmost distribution in Nicaragua. We present evidence, based on one specimen collected in 2005, confirming the presence of this species in the Caribbean of Honduras within the Islas de la Bahía department. This discovery increases the count of known species within this family to 18 in the country and raises the total bat species count for Honduras to 114. We recommend a detailed study of historical specimens to confirm the identification of species that may have been misidentified as well as a thorough examination of molossids distributed in northern Honduras.

Bat diversity, Caribbean islands, Central America, distribution, Islas de la Bahía, morphology

Currently, 113 bat species has been reported for Honduras (Turcios-Casco et al. 2020b; Mora et al. 2021), new records which include: Lasiurus cinereus (Palisot de Beauvois, 1796), Lasiurus egregius (Peters, 1870), Neoeptesicus brasiliensis (Desmarest, 1819), Balantiopteryx io Thomas, 1904, Vampyriscus nymphaea (Thomas, 1909), Nyctinomops aurispinosus (Peale, 1848), N. macrotis (Gray, 1840), Hylonycteris underwoodi Thomas, 1903, Chiroderma gorgasi Handley, 1960, Diaemus youngii (Jentink 1893), Natalus lanatus Tejedor, 2005, Cynomops mexicanus (Jones and Genoways 1967) and Centronycteris centralis Thomas, 1912 (Espinal and Mora 2012; Mora 2012; Divoll and Buck 2013; Mora et al. 2014; Espinal et al. 2016, 2021; Mora et al. 2016; Turcios-Casco and Medina-Fitoria 2019; Turcios-Casco et al. 2020a, b). One of the major issues with Honduran bat studies is that there are several historically-preserved specimens that have not been verified yet. For example, museum specimens of Natalus lanatus and Cynomops mexicanus reported by Turcios-Casco et al. (2020b) were collected in 1963 and 1967, respectively. Collecting and recording efforts have increased in the past 15 years, raising the number of bat species to 113 (Turcios-Casco et al. 2020b). Turcios-Casco et al. (2020b) and Mora et al. (2021), expect additional species to occur based on their wide distributions in Central America these include: Cormura brevirostris (Wagner, 1843), Lampronycteris brachyotis (Dobson, 1879), Trinycteris nicefori (Sanborn, 1949), Mesophylla macconnelli (Thomas, 1901), Molossus coibensis J. A. Allen, 1904, Molossus pretiosus Miller, 1902 and Thyroptera discifera (Lichtenstein & Peters, 1855). Historical collections from Honduras in international museums remain poorly assessed, and verification of the identification of many species (e.g., in the genera Natalus, Molossus, Eumops and phyllostomines) not only of bats (e.g., rodents such as Peromyscus, shrews such as Cryptotis) remains unclarified.

One of the most contentious bat families in Central America is Molossidae, because their overlapping external characters [see diagnoses in Loureiro et al. (2018, 2019, 2020)] make field identification difficult, and also because most of their echolocation calls have not been verified within their distribution (B. Miller, pers. comm.). Therefore, taxonomic identification of Central American molossids remains problematic and unresolved.

Among molossids, the Miller’s Mastiff Bat, Molossus pretiosus, has been considered widely distributed (Loureiro et al. 2019), and even though some authors consider it to be distributed far north as Mexico and southward to Brazil (e.g., Simmons 2005; Medina-Fitoria 2014; Cláudio et al. 2018; Díaz et al. 2021), the species was not included in Mexico by Ramírez-Pulido et al. (2014). Additionally, historical specimens in the Global Information Biodiversity Facility (GBIF.org 2023) database that have been identified as M. pretiosus were recorded from Belize and Mexico. The majority of the specimens identified as M. pretiosus in northern Central America, especially from Mexico and Belize, must be confirmed, as they could have been confused with other species of Molossus (B. Miller, pers. comm.). This occurrence was supported by Díaz et al. (2021) who included M. pretiosus in the bat checklist for Mexico and Costa Rica but not for Belize. Burgin et al. (2020) also confirm the species in Mexico and Belize. In contrast, other authors considered Nicaragua as the northernmost country within its range (e.g., Loureiro et al. 2019; Jennings et al. 2000; Simmons and Cirranello 2023). As described above, there is controversy over the distribution of M. pretiosus in northern Mesoamerica. As part of an effort to further investigate museum specimens from Honduras, we present evidence that confirms the occurrence of M. pretiosus on the Caribbean Island of Roatán in northern Honduras.

In addition to M. alvarezi, M. aztecus, M. bondae, M. molossus and M. nigricans, we present the record of a sixth Molossus species to Honduras, M. pretiosus. This brings the total number of molossids known to occur in Honduras to 18 [Cynomops greenhalli Goodwin, 1958; C. mexicanus; Eumops auripendulus (Shaw, 1800); Eumops ferox (Gundlach, 1961); Eumops hansae Sanborn, 1932; Eumops nanus (Miller, 1900); Eumops underwoodi (Goodwin, 1940); N. aurispinosus; Nyctinomops laticaudatus (É. Geoffroy, 1805); N. macrotis; Promops centralis Thomas, 1915; and Tadarida brasiliensis (I. Geoffroy, 1824)]; and increases the current list of bat species for Honduras to 114 (see Turcios-Casco et al. 2020b). There are still poorly known molossids in the country; T. brasiliensis, one of the most common and widespread species of molossid (Kunz et al. 1995), is known from two official records, one in western Honduras in Ocotepeque and another in the central region of the country in Francisco Morazán (McCarthy et al. 1993; Turcios-Casco et al. 2021). In addition, M. aztecus is only known from historical records from La Paz in western Honduras, supported by the revision of McCarthy et al. (1993) of museum specimens misidentified as M. bondae by Goodwin (1942).

Molossidae is still an understudied mammalian group in Honduras. One of the major issues of studying the group in the country is that many of them lack a robust and verified database of their echolocation calls, besides the limited sampling that has been done on bat acoustics since 1999 in Honduras (B. Miller pers. comm.). Reasons for this lack of information also include the small number of researchers interested in the family in Honduras, acoustic research being a recent addition to bat monitoring, and the relatively new use of canopy nets (B. Miller. pers. comm.). The natural history and ecological behaviour of molossids, which typically forage above mist nets, also present challenges to their study (Simmons 2005; Cláudio et al. 2018; Díaz et al. 2021). The under-utilization and lack of revision of historical mammalian specimens from Honduras present significant obstacles to accurately describing the biogeography of these animals. Misidentifications resulting from outdated taxonomy can impede efforts to elucidate the historical ranges of species, hindering our understanding of past ecosystems and potentially influencing modern conservation strategies.

The record of M. pretiosus presented herein for Honduras fills the gap in the northern portion of its distribution (Fig. 1) and indicates that it may be present in other regions of northern Mesoamerica. Since there is still some uncertainty about the northern limits of the distribution of the species, we strongly recommend revisiting museum specimens of M. pretiosus in northern Mesoamerica (e.g., Mexico and Belize) and verifying calls of molossids in Central America to identify other characteristics (e.g., bioacoustics) for molossid species identification as well as analysing molecular data whenever possible. Additionally, special attention must be given to the population in the Caribbean islands of Honduras because molossids in this region could probably be misidentified due to the overlap of external characters. To avoid the misidentification of specimens, we recommend the use of a larger set of morphological traits during field identification, such as forearm length, shape and length of upper indictors, fur colour and pattern of banding (see Loureiro et al. 2018, 2019, 2020; Díaz et al. 2021). Also, the collection and deposition of voucher specimens in scientific collections are encouraged in order to verify and confirm field identifications. Finally, the proper preparation of museum specimens such as skull, skeletons, skins, and tissues for further molecular studies is fundamental, especially for problematic groups like Molossidae.

To Phaedra Kokkini and Paula Jenkins from the Mammal Section of the Natural History Museum of London for providing information and photos of the specimen NHMUK 1984.1634 and the collection made by B.H. Gaskell. To Bruce Miller for his comments on Central American bat calls. To Monica Díaz, Sergio Solari, Nilton Cáceres, Polina Petrakieva and Christopher Glasby for their useful comments that helped to improve this manuscript. Photos of the ACUNHC specimen were taken by Nil Santana. MATC has received a scholarship from CAPES for the Programa de Pós-Graduação em Zoologia da Universidade Estadual de Santa Cruz (UESC), edital UESC n° 176/2022. TL received financial support from the Clark Stevens Endowed Chair. VCC has received support from Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ, E-26/205.820/2022 and 205.821/2022).