Malpaisomys Hutterer, Lopez-Martinez, and Michaux 1988

Malpaisomys Hutterer, Lopez-Martinez, and Michaux 1988, Palaeovertebrata, 18: 246.

Type Species: Malpaisomys insularis Hutterer, Lopez-Martinez, and Michaux 1988

Species and subspecies: 1 species:

Species Malpaisomys insularis Hutterer, Lopez-Martinez, and Michaux 1988

Discussion: Oenomys Division. Represented only by late Pleistocene and Holocene samples. A phylogenetic analysis by Hutterer et al. (1988) using 27 morphological traits placed Malpaisomys in a monophyletic group with the extinct Stephanomys (late Miocene to late Pliocene of Europe and N Africa) and the deomyines Acomys and Uranomys, to the exclusion of Rattus and Mus . A subsequent cladistic study with 17 cranial and 23 dental characters supported a very close phylogenetic association between Malpaisomys and Stephanomys, and an alliance between those two genera and Acomys on one hand, and Thamnomys and Oenomys on the other (López-Martínez et al., 1998). A study of antibody reaction against albumin of Malpaisomys, Acomys, Uranomys, and Mus (bone extracts were used for Malpaisomys) indicated Malpaisomys to be allied with Mus to the exclusion of Acomys and Uranomys (Montgelard, 1992) . We would like to see results from a phylogenetic study incorporating a greater range of murine genera and genes; until then we view the hypothesis by López-Martínez et al. (1998) to best estimate phylogenetic affinities of Malpaisomys and allocate it to our Oenomys Division. Certainly molar occlusal patterns are similar to those characterizing genera in that cluster.

Two species of Canariomys, also probably in the Oenomys Division, along with Malpaisomys, represent the known murine fauna once endemic to the Canary Isls and now apparently extinct (Boye et al., 1992; Hutterer et al., 1988; Lopez-Martinez and Lopez-Jurado, 1987; Michaux et al., 1996 c). Canariomys bravoi is represented only by Pleistocene and possibly Holocene specimens from Tenerife Isl. There are abundant remains from several archaeological sites (Michaux et al., 1996 c; Alcover et al., 1998); some specimens have been 14 C-dated as 12,230 " 140 years before present (Michaux et al., 1996 c). This is much earlier than human arrival to the Canary Islands, about 500 BC. The 14 C date, however, does not indicate date of extinction for C. bravoi and humans may have been contemporaneous because recently a mummified specimen has been found (Alcover et al., 1998). Canariomys tamarani, from Gran Canaria Isl (Lopez-Martinez and Lopez-Jurado, 1987), was terrestrial, herbivorous and is known only by specimens from the Holocene to pre-Hispanic epoch (about 2000 years before present). Fossils have been found associated with remains of goats, dogs, and Mus musculus in sediments dated at 130 years BC so C. tamarani and humans overlapped for a time (Lopez-Martinez and Lopez-Jurado, 1987). While Malpaisomys was small (estimated weight about 40 grams; Boye et al., 1992), the two species of Canariomys were large rats, up to one kilogram or more (Michaux et al., 1996 c). The two genera are not sympatric on any island. Malpaisomys has been found only on the three eastern isls (Fuerteventura, Lanzarote, and Graciosa); the two large central isls (Tenerife and Gran Canaria) are provenances of Canariomys . No endemic murines have been discovered on the western isls. A cladistic analysis by Lopez-Martinez and Lopez-Jurado (1987) suggested that C. bravoi and C. tamarani were in the same monophyletic group, a cluster related to the African Pelomys-Arvicanthis assemblage. However, a phylogenetic analysis by Hutterer et al. (1988) indicated that each species of Canariomys was in a different monophyletic cluster, C. bravoi with Grammomys dolichurus and Oenomys hypoxanthus, and C. tamarani with Arvicanthis niloticus and Rattus rattus . Careful re-examination of specimens will be necessary to resolve these contrasting views.

Lopez-Martinez and Lopez-Jurado (1987) regarded the two species of Canariomys as an emigrant relict from an African Miocene fauna. Malpaisomys, also a member of the Oenomys Division, likely represents a separate emigrant invasion of the isls (R. Hutterer, in litt., 2003). Possibly the closest phylogenetic relatives of these three species will prove to be extinct murines represented by Miocene and Pliocene fossils.