Thursday, July 7, 2016

[Mammalogy • 2016] Petrosaltator gen. nov., A New Genus Replacement for the North African Sengi Elephantulus rozeti (Macroscelidea; Macroscelididae)

FIGURE 3. Images of the three genera of the tribe Macroscelidini.
A. Basking North African sengi (Petrosaltator rozeti). Adult male near Salas village, Jhilet Mountains, Marrakesh, Morocco on 18 July 2005, specimen number CAS MAM 27982. Photo G. Rathbun.
B. The four-toed sengi (Petrodromus tetradactylus), Mareja Community Reserve, Pemba, northern Mozambique, 17 June 2011, specimen number CAS MAM 29347, Photo G. Rathbun.
C. The Namib round-eared sengi (Macroscelides flavicaudatus), south of the Micberg formation, Kunene Region, Khorixas District, 7 May 2010, specimen number CAS MAM 29700, photo J.P. Dumbacher.

In 2003, a molecular phylogeny was published that examined the role of the Sahara Desert as a vicariant event in the evolution of sengis (also known as elephant-shrews.) The phylogeny included a single sample from the North African sengi, Elephantulus rozeti (Duvernoy, 1833), which was found to be more closely related to the sengi genus Petrodromus Peters, 1846 than to other Elephantulus. Here we independently test the monophyly of Elephantulus using an additional specimen of E. rozeti and similar phylogenetic analyses, and discuss additional morphological and behavioral data that support the phylogeny. We propose a revised taxonomy that reflects the current paraphyly of Elephantulus and the sister relationship of E. rozeti and Petrodromus, including a new genus name for the North African sengi, Petrosaltator rozeti gen. nov., nov. comb. We additionally define two tribes within the subfamily Macroscelidinae, the Macroscelidini (including Macroscelides, Petrodromus, and Petrosaltator), and the Elephantulini (including all other members of Elephantulus).

Keywords: Mammalia, Sengi, Elephant-shrew, Petrosaltator, North African Sengi

Basking North African sengi Petrosaltator rozeti. Adult male near Salas village, Jhilet Mountains, Marrakesh, Morocco on 18 July 2005, specimen number CAS MAM 27982.
Photo G. Rathbun.   DOI: 10.11646/zootaxa.4136.3.8

Petrosaltator Rathbun and Dumbacher, new genus

Type species: Petrosaltator rozeti (Duvernoy, 1833)

Holotype. The type specimen is located at Musée Zoologique de la ville de Strasbourg, France; specimen number MZSMAM03685.

Geographic distribution. Petrosaltator has a unique range, and is currently the only species of the family Macroscelididae that occurs north of the Sahara Desert. It is known from the Maghreb Region of northern Africa, in Mediterranean, sub-desert, and montane zones from near sea level to 2725m elevation (Fig. 1) (Corbet & Hanks 1968; Cuzin & Séguignes 1990).

Diagnosis and description. The genus Petrosaltator is monotypic (P. rozeti) (Corbet & Hanks 1968; Duvernoy 1833; Perrin & Rathbun 2013). Features that distinguish the genus from all other Macroscelidinae are rare (see below), thus explaining why it was included in Elephantulus by earlier workers. Genetic data are among the most useful diagnostic characters, and have been used here and elsewhere to identify P. rozeti and clearly align it with Petrodromus and Macroscelides (Douady et al. 2003; Kuntner et al. 2011; Smit et al. 2011).

Etymology. The roots of Petrosaltator (masculine gender) are Greek (petro) and Latin (saltator), together meaning “rockdancer”. This genus name reflects the habitats occupied by this species, which are dominated by rocks and boulders (Séguignes 1988). Petrosaltator also alludes to the phylogenetic relationship with Petrodromus (meaning rockrunner with Greek roots), although oddly Petrodromus tetradactylus is not specifically a petrophile (Jennings & Rathbun 2001). We suggest that the common name of Petrosaltator rozeti continue to be the North African Sengi or Elephant-shrew

The taxonomic hierarchy for the subfamily Macroscelidinae follows:

Class: Mammalia Linneus, 1758
 Supercohort: Afrotheria Stanhope et al., 1998
 Order: Macroscelidea Butler, 1956

 Family: Macroscelididae Bonaparte, 1838
 Subfamily: Macroscelidinae Bonaparte, 1838

 Tribe: Macroscelidini, new tribe
 Genus: Macroscelides A. Smith 1829
 Genus: Petrodromus Peters 1846
 Genus: Petrosaltator, new genus

 Tribe: Elephantulini, new tribe
 Genus: Elephantulus Thomas & Schwann 1906

Macroscelidini, New Tribe
Type genus: Macroscelides A. Smith 1829
Description: The tribe is defined primarily by the genera included—Macroscelides, Petrodromus, and Petrosaltator. Synapomorphies recovered from genetic analyses include portions of vWF, IRBP, and mtDNA 12s–16s ribosomal RNA loci, which are all consistent with the monophyly of the tribe. Morphological synapomorphies for the group are not easy to discern, although these may include a penis with two lateral lobes and a narrowing end (Woodall 1995b) and the presence of a fully ossified stapediofacial tube (Benoit et al. 2013). Analyses of basal skull morphometrics also appear to support the monophyly of Macroscelidini (Scalici & Panchetti 2011).

Elephantulini, New Tribe
Type Genus: Elephantulus Thomas and Schwann, 1906, by monotypy

Description: The tribe provisionally includes only members of the genus Elephantulus (not including Petrosaltator rozeti) and is supported primarily by genetic synapomorphies. All members have three pairs of mammae, hallux present, auditory bullae not grossly inflated (Corbet & Hanks 1968), and penis morphology in which the urethra does not extend beyond the lateral lobes (Woodall 1995b). Not all members of the genus Elephantulus have been included in phylogenetic studies, so we include all members provisionally. 

In addition to the placement of P. rozeti with Petrodromus and Macroscelides into the tribe Macroscelidini, our genetic data suggest a possible phylogenetic split within Petrodromus tetradactylus, with one population in the Udzungwa Mountains of Tanzania (CASMAM28170 and CASMAM28171) and another occurring from at least southeastern Tanzania (Douady et al. 2003) to KwaZulu Natal in South Africa (GenBank numbers EU136156, EU136145, and EU136138), at the southern end of the current distribution of the genus (Rathbun 2015). Divergence within Petrodromus tetradactylus suggests that more research is needed to understand subspecies diversity in this monotypic genus. 

With our renaming of Petrosaltator, the subfamily Macroscelidinae now contains four genera (Elephantulus, Macroscelides, Petrosaltator, and Petrodromus). The number of extant species in the order, however, remains the same at 19 (Dumbacher et al. 2014). The diversity of extant taxa within the order continues to slowly increase with a better understanding of the underlying phylogenetics. Although this trend may continue as we learn more, extant species diversity in the order Macroscelidea remains remarkably low compared to other non-Afrotherian mammalian radiations in Africa (Kingdon et al. 2013; Rathbun 2009).

John P. Dumbacher, Elizabeth J. Carlen and Galen B. Rathbun. 2016. Petrosaltator gen. nov., A New Genus Replacement for the North African Sengi Elephantulus rozeti (Macroscelidea; Macroscelididae). Zootaxa. 4136(3); DOI: 10.11646/zootaxa.4136.3.8