Acta Theriologica 48 (4): 571-573, 2003. PL ISSN 0001-7051

FRAGMENTA TI-IERIOLOGICA

Sexual identification of Galemys pyrenaicus

Jorge GONZÁLEZ-ESTEBAN, Idoia VILLATE and Enrique CASTIÉN

González-Esteban J., Villate 1. and Castién E. 2003. Sexual identification of Galemys pyrenaicus. Acta Theriologica 48: 571-573.

The absence of sexual dimorphism in Pyrenean desman Galemys pyrenaicus (E. Geoffroy, 1811) makes it difficult to sex live animals. This paper presents a method of sexing desmans observing their external genitals. Based in a sampling of 49 animals from the north of Spain, it was possible to identify the penis of males, independently of the age or season.

Carretera Donamaria, 15, 2" izq, E-31740 Santesteban, Navarra, Spain, e-mail: abanades@wanadoo.es (JG-E, IV); Servicio de Conservación de la Naturaleza, Gobierno de Navarra, Alhóndiga 1, E-31002 Pamplona, Spain (EC)

Key words: Galemys pyrenaicus, sexing, glans penis, masculinisation

The Pyrenean desman Galemys pyrenaicus (E. Geoffroy, 1811) is a small, semi-aquatic insectivore that does not exhibit sexual dimorphism in the body size (González-Esteban et al. 1999) or colouration (Richard 1986). The determination of sex in live animals is further hindered by the masculinisation of the external genitals in females. The female urinary papilla is long and narrow and its interna1 structure is similar to that of the penis in young males (Peyre 1955, 1962). Richard (1986) reported the posibility of distinguishing between the sex of adult animals during the reproductive season, as the open, pigmented vagina1 orifice is easily visible in females at this time of the year. Some researchers (Palmeirim and Hoffman 1983, Juckwer 1990, Nores et al. 1998) have used the morphology of the pubic symphysis as a criterion to sex live desmans, according to the observations made by Peyre (1957) regarding the sexual dimorphism in the pelvic girdle. By palpating the abdomen it is possible to feel a hard arch joining the two ischio-pubic extremities of the pelvis in adult males, which is not found in adult females. This clifference is not discernible in immature specimens as both males and females have s hard pelvic arch.

In order to assess the difficulty entailed in sexing live desmans, five trapping sessions were set in two streams located in the basin of the Bidasoa River (Navarra, northern Spain). These samplings were carried out in: February 1998, July 1998, Uarch 1999, August 1999, and July 2000. Partially submerged wire-mesh eel-traps were used to capture desmans without harming them, following the method

572 J. González-Esteban et al.

described by Richard (1973). Age of the animals was estimated by observation of dental wear, based on the criterion developed by González-Esteban et al. (2002). This criterion is used to determine whether the animals are under 1 year of age, between 1 and 2 years of age or over 2 years old.

A total of 49 desmans were captured. We examined the anal-genital region of al1 the animals by (1) palpating the lower abdomen area to identify the pelvic arch, as described by Peyre (1957), and (2) applying light pressure to the urinary papilla, from both sides and downwards, in order to extrude the glans in males.

Thirty-one animals exhibited a hard pelvic arch. It was possible to expose the glans in 26 of them and the urinary papilla was identified as a penis. Seven were young specimens less than 1 year old and 19 were adults. This species has an elongated, cone-shaped, pink-coloured glans with smooth skin which, in adult males, is wider at the base (Fig. la , b). The remaining 5 animals, which did not exhibit a glans, were less than 1 year old and had a long, narrow urinary papilla (Fig. lc), with an indentation in the dista1 part. These traits coincide with the

Fig. 1. Lateral view of the externa1 genitals of Galemys pyrenaicus: (a) young male (under 1 year of age), (b) adult male (over 2 years of age), (c) young female (under 1 year of age), (d) adult female (over 2 years of age). Abbreviations: ap - anal papilla, p - penis, up - urinary papilla. Scale bar: 1 mm. The prepuce was removed in males to expose the glans.

Sexing of Galemys 573

description provided by Peyre (1962) of the urinary papilla in females. One of the specimens had an open vaginal orifice with no pigmentation.

The pelvic arch in 18 of the animals was not noticeable being identified as adult females (Fig. Id). Al1 these animals presented an urinary papilla morphologically similar to the young females above described. Furthermore, 15 of them had an open vaginal orifice with black pigmentation between the anal and urinary papillae. The remaining 3 specimens presented the vaginal orifice closed; however, their iden- tification was easy due to the characteristic pigmentation and lack of fur.

Based on of these observations, we may conclude that it is possible to distinguish between male and female desmans through the examination and exploration by palpation of the urinary papilla, regardless the age or the reproductive cycle. With a simple and harmless manipulation of the animal, the glands in males can be easily and unmistakable observed.

Acknowledgements: The suggestions of two anonymous referees and Dr L. Rychlik substantially improved the original manuscript.

References

González-Esteban J., Castién E. and Gosálbez J . 1999. Morphological and colour variation in the Pyrenean desman Galemys pyrenaicus (Geoffroy, 1811). Zeitschrift für Saugetierkunde 64: 1-11.

González-Esteban J., Villate I., Castién E., Gosálbez J. and Rey 1. 2002. Age determination of Galemys pyrenaicus. Acta Theriologica 47: 107-1 12.

Juckwer E. A. 1990. Galemys pyrenaicus (Geoffroy, 1811) - Pyrenean-Desman. [In: Handbuch der Saugetiere Europas, Bd. 311, Insektenfresser - Herrentiere. J. Niethammer and F. Krapp, eds]. Aula-Verlag, Wiesbaden: 79-92.

Nores C., Ojeda F., Ruano A., Villate I., González J., Cano J. M. and García E. 1998. Estimating the population density of Galemys pyrenaicus in four Spanish rivers. Journal of Zoology, London 246: 454-457.

Palmeirim J. M. and Hoffman R. S. 1983. Galemys pyrenaicus. Mammalian Species 207: 1-5. Peyre A. 1955. Intersexualité du tractus génital femelle du Desman des Pyrénées (Galemys pyrenaicus

G.). Bulletin de la Société Zoologique de France 80: 132-138. Peyre A. 1957. Dimorphisme sexuel de la ceinture pelvienne d'un Mammifkre Insectivore, Galemys

pyrenaicus G. Compte Rendus de 1'Académie des Sciences de Paris 244: 118-120. Peyre A. 1962. Recherches sur l'intersexualité spécifique chez Galemys pyrenaicus, G. (Mammifere

Insectivore). Archives de Biologie 73: 1-174. Richard P. B. 1973. Capture, transport and husbandry of the Pyrenean desman. International Zoo

Yearbook 13: 174-177. Richard P. B. 1986. Le Desman des Pyrénées. Un mammifere inconnu a découvrir. Editions Le Rocher,

Monaco: 1-118.

Received 20 August 2002, accepted 6 July 2003.

Associate Editor was Leszek Rychlik.