A cave leech (Hirudinea, Erpobdellidae) from Croatia 
with unique morphological features

 

Croatobranchus mestrovi is a troglobitic leech from deep shaft-like caves in the Mt. Velebit, Dinaric karst, Croatia, living in cold (4-6 °C) water. 

Croatobranchus mestrovi was first found during the expedition "Lukina jama '94" just at the bottom of Lukina jama (-1392 m). It moves like a caterpillar (stretching-contracting motion) and has extremities, which look like small legs. It is was named Croatobranchus mestrovi. Genus Croatobranchus received the name from the country of origin and side extremities (most probably auxiliary respiratory organs - branchia). Species name mestrovi is in honour of academician Milan Meštrov, Croatian biologist. Another proposed name (after DNA analyisis) is Erpobdella mestrovi (Oceguera-Figueroa 2005), but Croatobranchus mestrovi is still in use (Sket 2008).

Its oral sucker extends to form four pairs of triangular tentacles, each with about five finger-like papillae, but widening into a marginally crenulated disc when attached to a substrate. Pairs of stiff, finger-like lateral projections, probably gills, occur along the body behind the clitellum. Somites are simple five-annulate. Despite the unique head morphology and the presence of lateral outgrowths, the anatomy and 18S rRNA gene sequence of this species indicate that it is a member of the Erpobdellidae, closely related to Dina (Sket 2001).

In recent years Croatobranchus mestrovi was found in a few deepest caves in the Mt. Velebit, at the bottom of Slovacka jama (-1320 m), Olimp (-531 m) and Velebita (-1026 m).

Particularly rich in troglobionts is the family Erpobdellidae. Some described or undescribed cave species are present in southern Europe (N Italy–Balkans–Turkey–Caucasus), their derivative is also the extraordinarily transformed Croatobranchus mestrovi form deep caves in the Croatian Dinaric mountains. Some undescribed species, probably erpobdellids, occur in caves of China and the US (Sket 2008).

      
Croatobranchus mestrovi at the bottom of the Velebita cave (-580 m). Photo: Dalibor Paar. Drawing: Kučinić et al. 1999.

 


 Erpobdella Mestrovi. Cave system Velebita, at -580 m. Photo: D.Bakšić
 

 


Croatobranchus Mestrovi. Cave system Velebita, at -580 m. Photo: D. Paar

 

References:

  1. Kerovec, M., Kučinić, M., Jalžic, B., 1999.: Croatobranchus mestrovi sp. n. -predstavnik nove endemske podzemne vrste pijavica. Spelolog 44/45, 35–36.

  2. Oceguera-Figueroa, Alejandro , León-Règagnon Virginia, Siddall, Mark E.  2005.: Phylogeny and revision of Erpobdelliformes (Annelida, Arhynchobdellida) from Mexico based on nuclear and mithochondrial gene sequences. Revista Mexicana de Biodiversidad 76 (2): 191-198.

  3. Sidall, Mark E., 2002.: Phylogeny of the leech family Erpobdellidae (Hirudinida : Oligochaeta). Invertebrate Systematics, 16, 1–6.

  4. Sket, B., Dovc, P., Jalžić, B., Kerovec, M., Kučinić, M., Trontelj, P, 2001.. : A cave leech (Hirudinea, Erpobdellidae) from Croatia with unique morphological features. Zoologica Scripta 30, 223–229. 

  5. Sket, B., Trontelj, P., 2008. Global diversity of leeches (Hirudinea) in freshwater. Hydrobiologia, 595: 129-137.