THERYA NOTES 2022, Vol. 3 : 104-109 DOI: 10.12933/therya_notes-22-79 ISSN 2954-3614

Confused identities: the case of the chauve–souris septième or chauve–souris brun–blanchâtre of Azara (1801)

Identidades confundidas: el caso del chauve–souris septième o chauve–souris brun–blanchâtre de Azara (1801)

Paul Smith1,2*, and Pablo Teta3

1FAUNA Paraguay. Encarnación, Paraguay.

2Para La Tierra, Centro IDEAL, Mariscal Estigarribia 321, Teniente Capurro, Pilar. Departamento Ñeembucú, Paraguay. E–mail: (PS).

3División Mastozoología, Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”, Avenida Ángel Gallardo 470, C1405DJR. Buenos Aires, Argentina. E–mail: (PT).

*Corresponding author

Félix de Azara described several species of bats in his seminal work on mammals of Paraguay in 1801. One of these bats, the chauve–souris septième or chauve–souris brun–blanchâtre, was used by É. Geoffroy St–Hilaire (1806) to describe his Vesp[ertilio]. villosissimus, a name currently applied to the southern hoary bat, Lasiurus (Aeorestes) villosissimus. The latter, in addition, is the type species of the genus Aeorestes Fitzinger 1870. In this contribution, through a reevaluation of the description provided by Azara (1801), we demonstrate that the chauve–souris septième or chauve–souris brun–blanchâtre is clearly referable to the subgenus Dasypterus W. Peters, 1870. Strict application of the rule of priority in this case would cause considerable and undesirable nomenclatural upheaval, including the synonymy of Nycticejus Ega Gervais, 1856 with Vesp[ertilio]. villosissimus É. Geoffroy St.–Hilaire, 1806 and the need of a new genus (or subgenus)-level name for hoary bats. We thus recommend preservation of current usage by declaring a neotype for Vesp[ertilio]. villosissimus É. Geoffroy St.–Hilaire, 1806 and proposing a new type species for Aeorestes Fitzinger, 1870.

Key words: Aeorestes; Dasypterus; Hoary Bats; Lasiurine bats; Lasiurus.

Félix de Azara describió varias especies de murciélagos en su trabajo seminal sobre los mamíferos del Paraguay en 1801. Uno de estos murciélagos, el chauve-souris septième o chauve-souris brun-blanchâtre fue utilizado por É. Geoffroy St-Hilaire (1806) para describir Vesp[ertilio]. villosissimus, un nombre que se aplica actualmente al murciélago escarchado gris del sur, Lasiurus (Aeorestesvillosissimus. Esta última, además, es la especie tipo de Aeorestes Fitzinger 1870. En esta contribución, a través de una reevaluación de la descripción proporcionada por Azara (1801), demostramos que el chauve-souris septième o chauve-souris brun-blanchâtre es claramente referible al subgénero Dasypterus W. Peters, 1870. La aplicación estricta de la regla de prioridad en este caso causaría una alteración nomenclatural considerable e indeseable, incluida la necesidad de sinonimizar Nycticejus Ega Gervais, 1856 bajo Vesp[ertilio]. villosissimus É. Geoffroy St-Hilaire, 1806 y la necesidad de un nuevo nombre genérico o subgenérico para los murciélagos escarchados grises. Por lo tanto, recomendamos la preservación del uso actual a través de la designación de un neotipo para Vesp[ertilio]. villosissimus É. Geoffroy St-Hilaire, 1806 y proponiendo una nueva especie tipo para el taxón Aeorestes Fitzinger, 1870.

Palabras clave: Aeorestes; Dasypterus; Lasiurinae; Lasiurus; murciélagos canosos.

© 2022 Asociación Mexicana de Mastozoología,

Félix de Azara (1742–1821) was a Spanish military engineer and pioneer in natural history studies in southern South America (Contreras 2010). Charged with delimiting of the borders of the Spanish and Portuguese crowns on the continent, he was sent to Buenos Aires and Asunción (at this time within the limits of the Virreinato del Río de La Plata), in representation of the Spanish king. When his Portuguese equivalent failed to show, he focused his attention on documenting the fauna, culture and geography of his new home, a broad area that he defined as “Paraguay and La Plata”, that includes modern day eastern Argentina, Paraguay, extreme southern Brazil and Uruguay. A detailed chronology of his life, movements and work was provided by Mones and Klappenbach (1997) and Contreras (2010).

The two volume “Essais sur l’histoire naturelle des Quadrupedes de la Province du Paraguay” (Azara 1801) was perhaps the first serious attempt to describe the mammal fauna of the Southern Cone of the continent. Much to the chagrin of the author, the French version (translated by L. E. Moreau–Saint–Méry) was an incomplete draft that he had sent to Europe for opinion, only to find out later that it had in fact been published. This prompted comments in the prologue of the Spanish version of the text “Apuntamientos para la historia natural de los quadrúpedos del Paragüay y Río de la Plata” (Azara 1802) to the effect that this Spanish version should be considered the finished item, as it contained corrections to the errors and additional species not figured in Azara (1801). Nonetheless, many of the scientific names coined by European academics (including É. Geoffroy St–Hilaire, Desmarest, Oken and Olfers among others), that were derived from Azara’s text (as Azara did not employ Linnean binomials), were based on this French version, even though the specimens described (the types) did not always correspond to those in the Spanish version (although not in this case).

Though Azara’s descriptions are well written for the time, a lack of biological training, coupled with a global underestimation of the extent of zoological variation in the 19th century, meant that not all of the animals in his descriptions have been identified conclusively, or correctly. Reviews of his texts on the didelphids (e. g., Voss et al. 2009) and rodents (Tate 1932; Contreras and Teta 2003; Pardiñas et al. 2007) have been published, but the descriptions of the bats have been largely assumed to be correct (given that many original scientific names were based upon them). However, the description of the chauve–souris septième or chauve–souris brun–blanchâtre (Azara 1801; Tome 2: 284), currently regarded as referring to the Southern Hoary Bat, and the basis of Lasiurus villosissimus, originally described as Vesp[ertilio]. villosissimus É. Geoffroy St–Hilaire, 1806, clearly does not refer to a hoary bat. A re–evaluation of the identity of this bat takes on renewed significance, given the recognition that this form, formerly considered a subspecies of Lasiurus cinereus (Palisot de Beauvois 1796) by Sanborn and Crespo (1957), is in fact a different species (Baird et al. 2015). In addition, Vesp[ertilio]. villosissimus is the type species of the genus level name Aeorestes Fitzinger, 1870 by original designation.

Disagreement as to the identity of Vesp[ertilio]. villosissimus is not new (see Allen 1901, 1905; Thomas 1901, 1902, 1910). Though Allen (1901) originally considered the name to refer to Vespertilio bonariensis Lesson and Garnot, 1827 (at this time, the name applied in part to the South American “red bats”), he later associated it with Dasypterus W. Peters, 1870 (Allen 1905). On the other hand, Thomas (1901, 1902, 1910) consistently maintained that the bat described by Azara (1801) corresponded to L. cinereus (at this time, the name used for the South American “hoary bats”). Allen (1905) provided a convincing argument to link Azara’s chauve–souris septième or chauve–souris brun–blanchâtre with Dasypterus, but Thomas (1910) did not accept the suggestion, although he did concede it was “a little more plausible”. Allen (1905:190–191) reasoned: “(1) That it [i.e., Vesp[ertilio]. villosissimus] was of about the size of L. borealis, having a wing span of about 317 mm. (2) That it had a rather long, pointed ear, much larger and differently shaped than the ear of Lasiurus sensu lato. (3) That the naked edges of the interfemoral membrane, do not exist in the L. borealis group, and are only slightly seen in the L. cinereus group. (4) That the extreme softness, great length, and the color of the pelage, does not agree in any respect with that of L. borealis, nor very well with that of L. cinereus, but does agree in length and softness with the Dasypterus ega group.” Subsequent authors (e. g, Cabrera 1958; Sanborn and Crespo 1957; Gardner and Handley 2007) did not discuss this issue again, tacitly accepting the opinion of Thomas (1910).

In this note, we discuss the identity of Vesp[ertilio]. villosissimus, through a re-evaluation of the original texts of Azara (1801, 1802) and application of our current knowledge of the genus Lasiurus. In addition, we include some notes on the type locality and the nomenclatural implications of possible name changes.

Notes on the identity of the Azara’s chauve–souris septième or chauve–souris brun–blanchâtre.

Azara (1801, 1802) described his chauve–souris septième or chauve–souris brun–blanchâtre as a species with extremely soft hair, an overall whitish-brown coloration and moderately long, pointed ears (Appendix 1–3). Azara (1801, 1802) also remarked that the uropatagium was hairy, except at its border, and of the same color as the body pelage (Appendix 1–3). The description of the furred uropatagium confirms that, within the context of the Paraguayan fauna, this bat is a species of Lasiurus Gray, 1831 sensu lato. The genus Lasiurus includes 3 subgenera (sometimes treated as genera), for which the names Lasiurus (broadly referred to as the red bats), Dasypterus (yellow bats), and Aeorestes (hoary bats) are used. Three species, representing the three recognized subgenera, are documented for Paraguay (De La Sancha et al. 2017): Lasiurus (Lasiurus) blossevillii (Lesson, 1826), L. (Aeorestes) villosissimus (É. Geoffroy St–Hilaire, 1806) and L. (Dasypterus) ega (Gervais, 1856) (López-González 2005). However, while both L. blossevillii and L. villosissimus have their uropatagia covered by hairs almost to the border, L. ega has it furred only in the proximal half.

Though the description of this bat is brief, there are no grounds for associating a bat described as having “whitish–brown” pelage with the clade of hoary bats, which are distinctively–colored with frosted dark grey–and–white body fur and an obvious yellowish “balaclava,” or the red bats, which are characterized by a reddish coloration frosted with white (e. g., Shump and Shump 1982a, 1982b; Kurta and Lehr 1995; Díaz et al. 2011). In turn, L. ega has a yellowish–olivaceous to brownish coloration (cf. López-González 2005), more in accordance with the description made by Azara (1801, 1802). Finally, L. ega has more pointed and moderately long ears, contrasting with the shorter and more rounded pinna of the other two species (cf. Barquez et al. 1999). That Azara (1801, 1802) is indeed describing an individual of the species currently referred as L. ega is supported circumstantially by the fact that the morphometrics are consistent (though not diagnostic) with the measurements of L. ega (Table 1) and the fact that this species is a much more common bat than L. villosissimus in Paraguay (López-González 2005).

Notes on type locality.

Azara (1801, 1802) does not provide a type locality for the chauve–souris septième, chauve–souris brun–blanchâtre or murcielago blanquizco, noting merely that he had “several identical specimens”. However, Azara (in Agacino 1941) stated that his Morcielago 5to (= murcielago blanquizo) was captured in the house of Dr. Ignacio Pazos during February and that the specimen had been given to Azara. From the near identical text and the identical measurements, it is clear that this refers to the same species as the chauve–souris septième or chauve–souris brun–blanchâtre. The restriction of the type locality of L. cinereus villosissimus made by Cabrera (1958) to Asunción is thus accurate, based on the available data. Ignacio Pazos (born La Coruña, Spain 1760, died Cádiz, Spain 3 October 1804) was a naval officer and geographer, who formed part of an expedition to delimit the Spanish territories in South America, and worked closely with Azara during his time in Paraguay. The type specimen is now lost (Carter and Dolan 1978).

Nomenclatural implications.

Vesp[ertilio]. villosissimus É. Geoffroy St.–Hilaire, 1806 is based on the chauve–souris septième or chauve–souris brun–blanchâtre of Azara (1801). However, as demonstrated here and by Allen (1905), Vesp[ertilio]. villosissimus É. Geoffroy St.–Hilaire, 1806 is in fact a senior synonym of L. ega and has date priority over Nycticejus Ega Gervais, 1856, the current valid name for the Southern Yellow Bat. Strict application of the rule of priority in this case would cause considerable and undesirable nomenclatural upheaval and may be summarized as follows:

1) The date priority of Vesp[ertilio]. villosissimus E. Geoffroy St.–Hilaire, 1806 over Nycticejus Ega Gervais, 1856 means that the scientific name of the Southern Yellow Bat would become Lasiurus (Dasypterus) villosissimus (E. Geoffroy St.–Hilaire, 1806), with type locality in Asunción, Paraguay. Such a change would be unfortunate, since D. ega is the name that has been applied to the southern yellow bats for more than 150 years (see Gardner and Handley 2007).

2) The species actually known as Lasiurus (Aeorestes) villosissimus, the Southern Hoary Bat, would be called by the next available name; i. e., Lasiurus (Aeorestes) grayi Tomes, 1857: 40, with type locality “Chili” (= Chile).

3) The genus-level name Aeorestes Fitzinger, 1870 (dated 13 October 1870), with Aeorestes villosissimus as type species, would become a senior synonym of Dasypterus W. Peters, 1870 (dated 22 December 1870, with Lasiurus intermedius as type species) and thus be applicable to the Yellow Bats, not the Hoary Bats.

4) No valid supraspecific names are available for the Hoary Bats and they would require a new name, either for use as a genus or subgenus.

In order to avoid all these undesirable and destabilizing nomenclatural changes, the authors of this note will formally request the International Commission on Zoological Nomenclature (ICZN) to use its plenary powers to conserve both the supraspecific and specific names for both species affected (i. e., those currently referred as L. ega and L. villosissimus). We thus recommend preservation of current usage by declaring a neotype for Vesp[ertilio]. villosissimus É. Geoffroy St.–Hilaire, 1806 and proposing a new type species for Aeorestes Fitzinger, 1870.

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Associated editor: Nicté Ordoñez-Garza

Submitted: August 2, 2021; Reviewed: May 2, 2022.

Accepted: May 9, 2022; Published on line: June 6, 2022.

Appendix 1

Transcription of the original French text of (Azara 1801; Tome 2, pp. 284–285) upon which the name Vesp[ertilio]. villosissimus E. Geoffroy St.–Hilaire, 1806 is based.




J'ai possé dé divers individus de cette espèce, et ils étoient identiques entre eux.

Longeur, 4 pouces i tiers (11 centimètres 2 tiers)

Queue, 23 lignes (5 centimètres)

Envergurs, 11 pouces et demi (31 centimètres un tiers).

Le poil est extrémement doux, plus long que d'ordinaire, et d'un brun très–blanchâtre. C'est de la même coleur qu'est la membrane de la queue ; cette dernière est velue, excepté dans sa bordure.

L'aile est couleur de mure, excepté les doigts et le voisinage du bras et du corps, que sont brun–blanchâtres. L'aile est unie au métatarse, et la membran que va à l'extrémité de la queue nait un peu plus haut ; les vertèbres de la queue sont très–longues et minces.

L'oreille est comme celle du rat ; elle est haute de 7 lignes (1 centimètre et demi) ; elle présente presque son ouverture en avant ; elle est un peu aiguë à sa pointe, un peu inclinée vers le front, et encore vers le côté, et de son intérieur nait une pointe aiguë comme celle d'une épée.

Le museau n'est pás aigu, et il est divisé, à son extrémité pelée, par un canal, comme celui de la Chauve–Souris précédente.

La mâchoire supérieure excède un peu ; mais cet excédant, et même un peu plus d'espace encore, manque d'os, et par conséquent d'incisives, et peut se retrousser facilement ; cependant plus en dedans est une longue canine de chaque côté, jointe à laquelle et vers la partie extérieure, est une petite dent aiguë, que l'on pourroit appeller incisive, si elle n'étoit pas démesurément éloignée de son analogue de l'autre côté.

Dans la mâchoire inférieure, l'on n'apercoit point d'incisives, mais le tact les découvre, et l'on voit, de chaque côté, une canine un peu plus grande que celle d'en haut.

Appendix 2

Translation of the French text of Azara (1801) (see above, Appendix 1).




I have possessed various individuals of this species, and they were identical to each other.

Length, 4 inches and a third (11 2/3 centimetres)

Tail, 23 lines (5 centimetres)

Wingspan, 11 and a half inches (31 1/3 centimetres)

The hair is extremely soft, longer than usual, and of a very whitish brown. The membrane of the tail is of the same color; the latter is hairy, except at its border.

The wing is blackberry–colored, except for the fingers and the area around the arm and the body, which are whitish–brown. The wing is united to the metatarsus, and the membrane that goes to the end of the tail inserts a little higher; the vertebrae of the tail are very long and thin.

The ear is like that of the rat; it is 7 lines high (1 1/2 centimetres); it almost presents its opening forward; it is a little sharp at its point, a little inclined towards the forehead, and again towards the side, and from its interior arises a sharp point like that of a sword.

The muzzle is not sharp, and it is divided, at its bare end, by a canal, like that of the previous bat.

The upper jaw protrudes a little; but this excess, and even a little more, lacks bones, and consequently lacks incisors too, and thus can be easily pushed in. Internally there is a long canine on each side, and next to it externally, is a small sharp tooth, which one would call an incisor, if it were not disproportionately distant from its equivalent on the other side.

In the lower jaw, it is not possible to see any incisors, but they can be felt, and on each side, there is a canine, a little larger than that above.

Appendix 3

Transcription of the original Spanish text of Azara (1802; Tome 2, pp. 303–304).



He pillado varios idénticos. Longitud 4 1/3 pulgadas: cola 1 11/12: braza 11 ½. El pelo es suavísimo, mas largo de lo regular, y pardo muy blanquizco. De este color es la membrana de la cola, que tiene pelos, ménos en la borda. El ala morada; y los dedos y la inmediacion del brazo y del cuerpo pardos blanquizcos. Dicha ala une al metatarso, naciendo poco mas arriba la membrana que va al fin de la cola. Oreja de Raton, alta 7 líneas, casi presenta delante su abertura, algo aguda en la punta, un poco inclinada para la frente y hácia el costado; y de lo interior sale una punta aguda como de espada. El hocico no agudo: la mandíbula superior excede un poco; pero este exceso y algo mas carece de hueso, y por consiguiente de incisivos, y se arremanga fácilmente: mas adentro hay en cada lado un colmillo largo, y junto á él hácia fuera un dientecillo agudo, que podría llamarse incisivo si no distase demasiado del del otro lado. No se ven incisivos abaxo, pero los encuentra el tacto; y hay un colmillo en cada lado algo menor que el de arriba.

Table 1. External measurements (mean ± standard deviation, and range) for Vesp[ertilio]. villosissimus and the 3 species currently included within Lasiurus found in Paraguay (cf. López–González 2005). Measurements for V. villosissimus were converted into mm using the French inch (“pie de París” o “pie de Rey”) and line (1 inch= 27.07 mm, 1 line = 2.23 mm).


Lasiurus blossevillii

Lasiurus ega

Vesp[ertilio]. villosissimus

Lasiurus villosissimus

Total length

Male: 103.4 ± 8.70

Male: 119.7 ± 4.80


Male: 130.3 ± 1.53

(89.0–110.0; n = 7)

(107.0–127.0; n = 35)

(129.0–132.0; n = 3)

Female: 107.2 ± 5.27

Female: 56.5 ± 3.72

Female: 131.6 ± 4.50

(97.0–119.0; n = 16)

(117.0–139.0; n = 31)

(127.1–136.0; n = 2)

Tail length

Male: 46.1 ± 7.22

Male: 53.5 ± 4.28


Male: 55.3 ± 6.81

(33.0–55.0; n = 7)

(45.0–61.0; n = 35)

(50.0–63.0; n = 3)

Female: 48.6 ± 3.35

Female: 56.5 ± 3.72

Female: 56.3 ± 3.21

(45.0–56.0; n = 16)

(48.0–63.0; n = 31)

(54.0–60.0; n = 3)






Ear length

Male: 12.0 ± 1.53

Male: 17.5 ± 4.55


Male: 15.7 ± 0.58

(10.0–14.0; n = 7)

(13.0–21.0; n = 35)

(15.0–16.0; n = 3)

Female: 12.3 ± 1.35

Female: 16.5 ± 1.63

Female: 16.0 ± 1.00


(9.0–14.0; n = 16)

(13.0–21.0; n = 31)

(15.0–17.0; n = 3)