Micronycteris (Schizonycteris) tresamici, Siles & Baker, 2020

Siles, Lizette & Baker, Robert J., 2020, Revision of the pale-bellied Micronycteris Gray, 1866 (Chiroptera, Phyllostomidae) with descriptions of two new species, Journal of Zoological Systematics and Evolutionary Research 58 (4), pp. 1411-1431 : 12-14

4.4.4 | Micronycteris (Schizonycteris) tresamici sp. nov.

M[icronycteris] minuta Larsen et al., 2011:696 , Appendix 1 A (specimen KU 142698).

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Holotype

Voucher TTU 103880 (Figure 6, Table 3); adult male; standard skin and skull deposited at the Natural Science Research Laboratory, Museum of Texas Tech University (Lubbock,Texas,USA).Collected on July 14, 2004, by Robert D. Bradley, Meredith J. Hamilton, and Ronald A. Van Den Bussche. Tissues and karyotype deposited at the same collection (TK 136127). The skin and skull are well preserved.

Type locality

Honduras: Atlántida Department; Lancetilla Botanical Gardens (15.734444°N, 87.456111°W; elevation 34 m).

Paratypes

Three additional specimens collected from Honduras and Costa Rica are designated as paratypes based on morphological and genetic data and are deposited at the Natural Science Research Laboratory, Museum of Texas Tech University (Lubbock, Texas, USA). Sequenced and measured voucher TTU 61057, tissues TK 40358; adult male; preserved in ethanol with the skull removed; collected on 6 August 1991 by Robert D. Bradley from Lancetilla Botanical Gardens (15.70°N, 87.4667°W; elevation 375 m), Atlántida Department, Honduras. Measured vouchers TTU 34279 and TTU 34280; adult males; preserved in ethanol with the skull removed; collected on June 10, 1977, by Ira F. Greenbaum ( Costa Rica: San José; “ 41.2 miles SW Canas ”). This locality is unclear because Cañas is not in San José, and a map by the collector locates this point together with a locality in Guanacaste 10 miles SSE Cañas ( Greenbaum, 1978). We follow VertNet's georeferenced point in Costa Rica: Guanacaste; 41.2 miles SW Cañas (10.0094604°N, 83.99194°W; elevation 270 m). No tissues available for these specimens .

Distribution

Honduras: Atlántida, and Costa Rica: Guanacaste and Alajuela (Figure 1). The record from Alajuela is based on morphometric data from voucher KU 142698 ( Costa Rica: Alajuela; Upala Canton , Dos Rios District , Finca of Alphonso Bustos 10.88333°N, 85.38333°W; elevation 375 m).

Etymology

The specific epithet tresamici is the Latin phrase “tres amici” (three friends) in apposition honoring the three scientists who captured and collected this new species in the forests of Honduras: Robert D. Bradley, Meredith J. Hamilton, and Ronald A. Van Den Bussche. According to their accounts, they owe their success in the field mainly to their friendship, teamwork, and enthusiasm for scientific collecting. In their professional life, they have contributed thousands of specimens to natural history collections and currently run research laboratories in Texas Tech University and Oklahoma State University.

Diagnosis

Ventral hair on throat and sternal region is white, whereas the abdominal area presents brown coloration similar to the dorsal hair. Rostrum is short oval in dorsal view, inflated in the region over P4, M1, and M2. Sagittal crest is low and present over the first third or the first half of the parietals. Palatine bones are long with a round shape anteriorly, and the sutura palatomaxillaris is located between M1 and M2. Lower incisors are brachydont and bilobed. P3 is shorter and narrower than P 4 in lateral view, and P3 is oval in occlusal view. A gap is present between the canines and I2 and between P3 and P4.

Micronycteris tresamici also can be distinguished from its congeners based on DNA sequence data.Phylogenetically,maternal (cytb), nuclear (Fgb -I7), and paternal (Y-chromosome DBY5 and DBY7) sequences position M. tresamici in a clade that is divergent and strongly supported from other members of the genus studied thus far.

Description and comparisons

M. tresamici is a small-sized bat, similar in size to all other pale-bellied species, but less robust than M. schmidtorum . External measurements (in mm): forearm 33.6–34, total body 42.3–53, tail 9–10.5, foot 9–10.7, ear 18–21, metacarpal III 25.3–26.5, metacarpal IV 26.6–27.3, thumb 7.2–9.1, tibia 10.3–15.2, and calcar 7.4–9.1. Cranial measurements are presented in Appendix 1. The dorsal fur is long (~ 8 mm in the shoulder region) and bicolored with brown tips and a white base that comprises approximately less than half of each hair (white portion ~ 3 mm). All pale-bellied species have bicolored dorsal fur that ranges from 6 to 10 mm, although some specimens of M. schmidtorum have pale buff base instead of white. The proportion of base hair varies considerably within M. minuta (1/4-3/5) and M. schmidtorum (1/2-2/3). Micronycteris tresamici and M. yatesi have the throat and sternal region completely white, whereas the abdominal area presents brown coloration similar to the dorsum. This pattern contrasts to M. sanborni that has the entire ventral region completely white, and M. brosseti , M. minuta , M. schmidtorum , and M. simmonsae sp. nov. that have pale gray or pale buff underparts, but never pure white ( Feijó et al., 2015; Siles et al., 2013). The ears are large with round tips and a midline-notched membrane connects their bases. Uropatagium and wing membranes are naked and hind feet are hirsute. The calcar is shorter than the foot in M. tresamici , but we agree with several authors that this is not a reliable diagnostic character ( Feijó et al., 2015; Santos et al., 2010; Siles et al., 2013).

The shape of the rostrum in dorsal view differs significantly among pale-bellied Micronycteris , and it is diagnostic. Micronycteris yatesi presents narrow, elongated, and slender rostrum (long-pyriform), which is slightly inflated in the region over P4 and M1; M. sanborni , M. simmonsae sp. nov., and M. minuta have short-pyriform rostra, with an inflated region over P4,M1, and M2; M. tresamici presents has a short-oval rostrum, inflated over P4, M1, and M2; M. brosseti , has a more triangular rostrum, inflated over M1 and M2; and M. schmidtorum has a triangular rostrum, without the inflated area over the premolars or molars. Although measurements of POC may not differ greatly, its shape relative to the cranium and rostrum can also be useful. M. tresamici the widest and most robust POC, followed by M. brosseti , M. yatesi , and M. simmonsae sp. nov.. The sagittal crest is diagnostic as well, M. schmidtorum and M. simmonsae sp. nov. present a low crest over the parietals, and in M. schmidtorum can extend over the frontals; M. tresamici and some specimens of M. minuta present a low sagittal crest over the first third, first half, or two thirds of the parietals, and it is absent in M. brosseti , M. sanborni , M. yatesi , and some specimens of M. minuta . The lambdoidal crest is absent in all pale-bellied Micronycteris . In lateral view, the cranium is tall in relation to the rostrum in the subgenus Leuconycteris and forms an angle of 30° to 35°. In the subgenus Schizonycteris , this angle is variable, in M. minuta , M. simmonsae sp. nov., and M. tresamici is 19–26°, and in M. sanborni and M. yatesi is 20°-23°. The palatine bones are long with the sutura palatomaxillaris located between M1 and M 2 in all pale-bellied species except M. yatesi , which has shorter palatines with the sutura palatomaxillaris located between M2 and M3. The basisphenoid pits are deep in M. brosseti , M. sanborni , M. simmonsae sp. nov., M. tresamici , and M. yatesi ; it can be either deep or shallow in M. schmidtorum ; and in M. minuta , it is shallow in individuals from northern South America and deep in individuals from southern South America.

Upper inner incisors (I1) are unilobed and similar in shape and size in all pale-bellied species, with a few specimens with bilobed I 1 in M. minuta and M. schmidtorum . Upper lateral incisors (I2) are unilobed, convergent, and small, less than one-half the size of the upper inner incisors in all Schizonycteris ; however, the shape and presence of lobes is variable in M. minuta . A gap between I2 and the canines is present in M. tresamici , M. yatesi , and it can be present or absent in M. sanborni and M. minuta ( Feijó et al., 2015) .In lateral view,P3 and P4 are equal or similar in size in M. schmidtorum , M. brosseti , and M. simmonsae sp. nov., with P3 slightly shorter than P 4 in some members; P3 smaller (shorter and narrower) than P 4 in M. tresamici , M. sanborni , and M. yatesi ; and in M. minuta P3 is shorter than P4, and variable in width,that is,P3 is broader or equal than P 4 in individuals from northern South America and narrower or equal in individuals from southern South America. In occlusal view, P3 is oval in M. tresamici , M.schmidtorum , M. brosseti , and some members of M. minuta , round in M. sanborni , and rectangular/square in M. yatesi , M. simmonsae sp. nov., and most M. minuta . There is a gap between P3 and P 4 in M. tresamici , and some members of M. brosseti , M. minuta , and M. sanborni . No gap between P3 and P 4 in M. schmidtorum , M. minuta , M. simmonsae sp. nov., and M. yatesi . Lower incisors are brachydont and bilobed in Schizonycteris and M. brosseti , whereas they are hypsodont and bi or trilobed in M. schmidtorum . Lower premolars are very robust in M. schmidtorum , and robust in M. brosseti , both species with p3 slightly smaller than p2 and p4 (p2≈p4> p3), whereas in Schizonycteris p3 is much smaller and only p2 is robust (p2> p4>p3).

The karyotype has 2n = 28 and FN = 50 (Figure 4) and comprises 12 biarmed chromosome pairs, three of which have a subtelocentric morphology. The X is a medium-sized submetacentric, whereas the Y has a dot-like morphology. This karyotype is identical in M. minuta , M. sanborni , and M. simmonsae sp. nov. and apparently is characteristic of the subgenus Schizonycteris .

Habitat and ecology

Lancetilla is a botanical garden located in the northwestern region of Honduras and consists of productive forest plantations (393 ha), an arboretum (16.4 ha), and a biological reserve (1,503 ha) ( Ponce, 2011). It is a mountainous area classified as tropical moist forest (sensu Holdridge life zones) with an altitude range of 20 to 600 m. The microbasin has a main drainage to the Lancetilla River (10 km of length) and belongs to the Lean River basin ( Ponce, 2011). The climate is classified as tropical rainforest (sensu Köppen system), with an average annual rainfall of 3,278 mm, a rainy season from August to December, a dry season from January to July, an average annual relative humidity of 82%, and an average annual temperature of 25°C in the valleys and 20°C in the highlands ( Ponce, 2011). The vegetation is broadleaf evergreen moist forest and plantations of rambutan ( Nephelium lappaceum ),passion fruit ( Passiflora edulis ), African oil palm ( Elaeis guineensis ), among others ( Ponce, 2011).VertNet records show that bats were collected extensively in Lancetilla, and species include members of families Emballonuridae (2 species), Molossidae (5), Mormoopidae (3), Phyllostomidae (38), and Vespertilionidae (4).

Comments

Micronycteris tresamici is the sister clade to the rest of the subgenus Schizonycteris . It is genetically and morphologically divergent from any M. minuta morphotype;therefore,its junior synonyms M.hypoleuca and M. homezorum are not valid names for this taxon. Additional records from the type locality published as M. minuta by McCarthy, Davis, Hill, Jones, and Cruz (1993) and deposited at the Texas A&M Biodiversity Research and Teaching Collections (formerly Texas Cooperative Wildlife Collections) need to be assessed (specimens TCWC 49466–49470).