Bioacoustics of Pteronotus (Phyllodia) alitonus

Diagnosis.— Pteronotus alitonus is diagnosed as a distinct species by several independent characters including acoustic, molecular, and morphological data, allowing its recognition in the field, laboratory, and in scientific collections. This species can be easily identified in the field by its echolocation calls emitted between 59 and 60 KHz. P. alitonus has also been molecularly characterized, forming a cohesive mitochondrial clade diverging around 5% from its sister group, the species P. rubiginosus ; the polymorphic sites between P. alitonus and P. rubiginosus COI haplotypes are described in Fig. 6 . Cranially, P. alitonus can be distinguished by a unique combination of traits. It has a shorter rostrum, with nasals wider between the frontal and maxillary sutures, more convergent and slightly upturned at the distal part. The maxillary toothrow length (MxTL) is smaller than 9.7 mm and the IB/palatal length (PL) ratio is usually higher than 0.45. The foramina in the pterygoid canal vary from small to indistinct. The tips of upper outer incisors reach half or more of the height of upper inner incisors; they may be separated from the canines by a small gap (particularly noticeable in ventral view of the skull). Echolocation description.— Pteronotus alitonus has duty cycle signals consisting of a short upward frequency-modulated (FM) initial component, followed by a long CF component and a short downward FM terminal component (CF-FM signal; Supplementary Data SD6). The signal has few or no harmonics and, when present, the 2nd harmonic is the most intense. The echolocation calls have an average FME of 59.2 kHz (58.4– 61.5 kHz) and signal duration of 24.8 ms (7.0–40.0 ms), with great overlap between the localities recorded.

Nomenclatural statement. —A Life Science Identifier (LSID) number was obtained for the new species Pteronotus alitonus : urn:lsid:zoobank.org:act: 4B22D88F-77BA-4021-B031-B54B946DC52D . Historical background. —In the synonymy presented above (only with 1st use of the names), we tentatively listed authors that implicitly included in their concepts of Chilonycteris rubiginosa or P. parnellii , populations from northern Brazil and the Guianas, which could be assigned to the new species here described. The 2 latter synonyms represent not binomial (and more formal) entries, but refer to specimens whose association to this new species is clear and explicit. Several studies have been published in recent years evidencing the existence of 2 sympatric lineages of common mustached bats in the Amazonian region. Each of these studies has focused on specific questions about the group, but also provided additional sources of information to guide the present study. Based on information from 3 loci, Clare et al. (2013) described the existence of 4 distinct lineages in the continental range of the species formerly known as P. parnellii : 1 in Central America and 3 in South America. Two of these South American lineages, called Pteronotus sp. 3 and Pteronotus sp. 4 , were found in sympatry in Guyana and Suriname . Clare et al. (2013) also described information from acoustics and morphometrics related to the geographic areas of occurrence of these lineages. Thoisy et al. (2014) showed that the 2 sympatric lineages of the P. parnellii complex found by Clare et al. (2013) in Guyana and Suriname were acoustically discernible and increased their ranges to French Guiana and northern Brazil . Thoisy et al. (2014) provided molecular and morphometric evidence indicating that one of these lineages ( Pteronotus sp. 4 ) corresponds to P. parnellii rubiginosus , the taxon already known for that area. Later, Pavan and Marroig (2016) provided a new phylogenetic hypothesis and an updated taxonomic arrangement for the genus Pteronotus . Pavan and Marroig (2016) corroborated the existence of 8 distinct lineages within the P. parnellii complex (subgenus Phyllodia ), 1 in Mexico , 1 in Central America, 3 in South America, and 3 in the Caribbean, linking them to the available names in the group (as subspecies and species names) and showing that one of the sympatric lineages from South America ( Pteronotus sp. 1 —sensu Pavan and Marroig 2016; Pteronotus sp. 3 —sensu Clare et al. 2013 ) has no name available. Pavan and Marroig (2017) published a dated phylogeny for the genus Pteronotus based on the same molecular data published by Pavan and Marroig (2016). They discussed the historical processes related to the origin and diversification events within the group. López-Baucells et al. (2017) reported the existence of geographic variation in the echolocation calls of these 2 sympatric species of Pteronotus from South America. The study by López-Baucells et al. (2017) is complementary to Thoisy et al. (2014) because it showed that, despite the existence of intraspecific variation, both species are acoustically discernible, i.e., the differences are consistent across geography. They also provided additional information on the distribution of the unnamed lineage of Pteronotus in Central Amazon. We hypothesize that the Pteronotus sp. 3 (sensu Clare et al. 2013 ) and Pteronotus sp. 1 (sensu Pavan and Marroig 2016), as well as the specimens studied by Thoisy et al. (2014) and López-Baucells et al. (2017), can be confidently recognized as the same biological entity. We advocate this as we included part of their datasets in the present appraisal and carefully compared the results.