Molossus paranaensis Caraballo, Pavé, Argoitia, Schierloh & Chambi Velasquez, 2024

Chambi Velasquez, Micaela A., Pavé, Romina, Argoitia, María A., Schierloh, Pablo, Piccirilli, María G., Colombo, Valeria C., Beltrán, Fernando J., Cisterna, Daniel M. & Caraballo, Diego A., 2024, Revisiting Molossus (Mammalia: Chiroptera: Molossidae) diversity: Exploring southern limits and revealing a novel species in Argentina, Vertebrate Zoology 74, pp. 397-416 : 397-416

Molossus paranaensis Caraballo, Pavé, Argoitia, Schierloh & Chambi Velasquez sp. nov.

Chresonymy.

Molossus molossus – Pavé et al. (2017: 158)

Molossus molossus – Caraballo et al. (2020: 4)

Molossus molossus – Montani et al. (2021: 17)

Molossus molossus – Pavé et al. (2021: 17)

Molossus molossus – Pavé et al. (2023: 423)

Holotype.

MFA-ZV-M 1494 , adult male, preserved as skin, skull, and postcranial skeleton (Figs 4 , 5 ), collected on 20 January 2018 by M. E. Montani (MEM) and V. Colombo (field number MEM 237 ). External and craniodental measurements for the type series are presented in Table 1 . — Type locality. Sociedad Rural “ Las Colonias ”, Esperanza, Santa Fe province, Argentina (lat. – 31.4257, long. – 60.9912, 44 m). This is a rural area in the Espinal ecoregion (sensu Olson et al. 2001) where the natural vegetation has been highly transformed in farmlands and there is very little tree vegetation. At the site, there are native tree species such as Tipuana tipu ( Fabaceae ) as well as exotic species like Eucalyptus sp. ( Myrtales ) and Fraxinus sp. ( Oleaceae ) . Nine kilometers northeast of this site lies the Martín de la Peña Natural Reserve, characterized by its native vegetation.

Paratypes.

INALI-A 389 and 390 adult females, with INALI-A 389 preserved as a skull specimen only, while both specimens are preserved in 70 % alcohol, collected on October 2017 at “ Desvío Arijón ”, San Jerónimo, Santa Fe province, Argentina (lat. – 31.88, long. – 60.89, 17 m); MG-ZV-M 176 adult female preserved as skin, skull and postcranial skeleton, collected on 16 May 2015 at “ Reserva Hídrica Río Carcarañá ”, Area Natural Protegida, Pueblo Andino, Iriondo, Santa Fe province, Argentina (lat. – 32.67, long. – 60.87, 25 m); MG-ZV-M 208 adult female preserved as skin, skull, and postcranial skeleton, collected on 7 May 2016 at “ Parque Villarino ”, Zavalla, Rosario, Santa Fe province, Argentina (lat. – 33.03, long. – 60.89, 57 m); MG-ZV-M 296 and MFA-ZV-M 1414 subadult males preserved in 70 % alcohol from Rosario, Santa Fe province, Argentina (lat. – 32.69, long. – 60.72, 30 m); INALI-A 457 adult female preserved as skull and in 70 % alcohol, collected on 7 March 2018 at “ Estancia Las Gamas ”, Vera, Santa Fe province, Argentina (lat. – 29.42, long. – 60.38, 62 m); INALI-A 588 and 589 adult males with scrotal testes, preserved as skin, skull and postcranial skeleton the first and in 70 % alcohol the second, collected on 8 December 2018 at “ Establecimiento Inchala ”, La Picada, Paraná, Entre Ríos province, Argentina (lat. – 31.74, long. – 60.26, 29 m); MACN-Ma 30878 an adult male preserved as skull and in 70 % alcohol, collected on 7 April 2017 at “ Campus Universitario FaCENA-UNNE ”, Corrientes city, Corrientes province, Argentina (lat. – 27.47, long. – 58.78, 61 m); MACN-Ma 30420 adult male preserved in 70 % alcohol from Tigre, Buenos Aires province, Argentina (lat. – 34.42, long. – 58.57, 4 m).

Other specimens.

Five individuals, three males and two females, were captured using mist nets at “ Sociedad Rural ”, Santa Fe city, Santa Fe province, Argentina (lat. – 31.63, long. – 60.71, 20 m), obtained tissue samples, marked with a haircut and then released (collector Valeria Colombo number: MR 192, 193, 194, 197, 198).

Distribution and habitat.

This species is known from ten localities in four provinces of eastern Argentina (Buenos Aires, Corrientes, Entre Ríos, and Santa Fe) in the Espinal, Humid Chaco, Humid Pampas, and Paraná Flooded Savanna ecoregions (sensu Olson et al. 2001). Molossus paranaensis inhabits natural environments in pampas grasslands, dry shrublands and wetlands, and anthropic environments such as human constructions in cities and agricultural fields.

It is conceivable that this newly discovered species may have a wider distribution, particularly within the region influenced by the Paraná River.

Etymology.

The name paranaensis is bestowed in reference to the extended distribution of the new species along the Paraná River basin, one of the largest rivers in South America. Paraná is a word from the Mbyá people who speak Tupí (one of the native languages in Argentina), pará = “ sea ” and nã = “ similar to ” or “ like ”, which means “ that looks like the sea ” or “ similar to the sea ”. This river shelters a great biodiversity and natural beauty.

Diagnosis.

Molossus paranaensis is distinguished from all other Molossus species by the following combination of characters: medium size (FA 39.4–42.8 mm; GLS w. i 17.3–19.2 mm; PC 3.8–4.6 mm; LMxT 6.3–7.4 mm); dorsal coloration medium brown (cinnamon to grayish brown sensu Ridgway 1912) with individual hairs bicolored, with a large and pale basal band reaching 1 / 4 to 1 / 2 to of total length of the hair, the venter is paler than dorsum (Fig. 4 ); in frontal view the rostrum is triangular (Fig. 5 B ), and the lambdoidal crests are moderately developed (Fig. 5 ).

Description.

The new species is a medium-sized Molossus (ToL: 90.31–115 mm; FA: 39.4–42.84 mm, n = 13 specimens, 6 males and 7 females). Sexual dimorphism is observed in certain variables (body mass, ToL, CBL, MB, PL, C-C; see Table 1 ). Rostrum with a well-developed and straight keel, and the upper lip with a fringe of medium brown hard hairs on the border forming an upwardly projected mustache. Triangular and medium-sized ears (10–14.5 mm total length) with an oval-shaped antitragus that has an anterobasal constriction. Dorsal hairs measuring 5 mm long, markedly bicolored with a large pale band on the base from white to cream and the tips are variable from cinnamon to grayish brown (the holotype is cinnamon). Ventral hairs measuring 5 mm long, paler than the dorsal hairs and bicolored with grayish brown tips (buffy olive or citrine drab sensu Ridgway 1912; Fig. 4 ) and white or cream bases; ventrally, the pelage extends onto the plagiopatagium along the side of the body from the elbow to the knee. Wing membranes and uropatagium are pale brown. Feet have thickened first and fifth toes with short and curved hairs and all the toes are bordered with long, curved, and light hairs. The calcar is well-developed, longer than the hindfoot, and occupying ⅔ of the uropatagium edge.

The skull is elongated with a short rostrum (compared to the braincase); the infra-orbital foramen is frontally directed; the nasal cavity is taller than wide (in dorsal view the posterior edge of the nasal cavity is triangular); basisphenoid and basioccipitals pits moderately deep although the first more than the second; the occipital is triangular in posterior view; the sagittal crest has low development and the lambdoidal crest is moderately developed and has a quadrangular shape in posterior view as in M. fluminensis , both crests are more pronounced in males. The post-tympanic process of the squamosal is well developed and this is more visible dorsally (Fig. 5 D ). The dental formula is I 1 / 1, C 1 / 1, P 1 / 2, M 3 / 3, total = 26. The upper incisors are elongated, pincer-like, they are projected beyond the canines, and with parallel tips (Fig. 5 A, B ).

Comparisons.

Molossus paranaensis is a medium-sized Molossus similar to M. bondae , M. currentium , M. molossus , M. melini , and M. verrilli ( Loureiro et al. 2018 a) . The new species can be easily distinguished from M. bondae and M. verrilli by dorsal fur coloration and secondarily by geographical distribution. From the species occurring in Argentina, M. paranaensis differs from M. currentium in dorsal coloration and in some cranial characters such as the shape of upper incisors (see Table 2 ); from M. molossus in the length of forearm (in general <40 mm in M. molossus and 39.4–42.8 mm in M. paranaensis ) and LMTx (5.7–6.4 mm in M. molossus and 6.3–7.4 mm in M. paranaensis ), the format of the rostrum in frontal view (triangular in M. paranaensis and square in M. molossus ; Loureiro et al. 2018 a), the development of lambdoidal crests (moderately developed in M. paranaensis and underdeveloped in M. molossus ), and in several cranial measurements (see Figs 2 , 3 ; Table 2 ); from M. melini , in addition to the ochraceous or orange individuals of this last species, in the color of membranes (pale brown in M. paranaensis and dark brown in M. melini ), in the direction of the infra-orbital foramen (frontal in M. paranaensis and lateral in M. melini ), in the development of sagittal crest (higher in M. melini ), and in the length of LMxT (6.0–7.0 mm in M. melini and 6.3–7.4 mm in M. paranaensis ), PC (3.7–4.2 mm in M. melini and 3.8–4.6 mm in M. paranaensis ), and LMdT (6.4–7.9 mm in M. melini and 7.3–8.0 mm in M. paranaensis ) (Figs 2 , 3 ; Table 2 ).

Molossus paranaensis can be readily differentiated from larger-sized Molossus , such as M. alvarezi , M. fluminensis , M. nigricans , M. pretiosus , M. rufus , and M. sinaloae , all of which have forearm longer than 42.8 mm and dorsal color in general dark brown. Furthermore, among large-sized species, M. paranaensis occurs in sympatry only with M. fluminensis . Finally, M. paranaensis differs from M. aztecus , M. coibensis , M. fentoni , and M. milleri due to its larger forearm (see Table 2 ). Additionally, M. aztecus and M. coibensis exhibit unicolored dorsal hairs, spatulated upper incisors, and a quadrangular occipital region, while M. fentoni and M. milleri are characterized by their dark fur. The external and cranial differences distinguishing M. paranaensis from the other Molossus species are presented in Table 2 .

Figures

Figure 2. A Genetic confidence score (GIS) was defined for each species group by weighted consideration of known sequences (see File S 1 for equation details). Univariate pairwise comparisons of external (B) and cranial measurements (C) of Molossus species present in Argentina (and Brazil) based on genetically confirmed specimens (M. fluminensis, M. melini, M. molossus, and Molossus sp. nov.). Box-and-whisker plots show data distributed across quartiles, the vertical lines indicate the ranges, and outliers are shown as separate data points. *, **, and *** represent significant pairwise differences among species.

Figure 3. Principal component analysis (PCA) of selected cranial metric variables (GLS wo. i, CBL, PC, BB, ZB, MB, LMxT, PL, C-C, M 2 - M 2, LM and LMdT) of genetically confirmed specimens of Molossus distributed in Argentina. A PCA results are presented in a biplot chart with individuals (dots) and variables (blue arrows) plotted together in the PC 1 vs PC 2 space. Individuals of the same species are enclosed by a convex hull. The mass centroid of each group is indicated by an unlabeled plus sign. Data labels are referenced in File S 1 (Table M 3). Dot sizes of each specimen is proportional to its genetic information availability score (GIS, see File S 1 for score definition details). B Percentages of each cranial variable’s contribution to the first two principal components (Dim 1 and Dim 2).

Figure 4. Dorsal (A) and ventral (B) views of the skin of the holotype of Molossus paranaensis (MFA-ZV-M 1494), adult male. Scale bar = 10 mm.

Figure 5. Lateral view of skull and mandible (A), and frontal (B), ventral (C) and dorsal (E) views of the skull of the holotype of Molossus paranaensis (MF-ZV-M 1494). Scale bar = 10 mm.