How can a Dambo rat be differentiated? - briefly
A Dambo rat is identified by its unusually large, rounded ears, a short hairless tail, and a dark dorsal stripe running from the shoulders to the hips. It also displays a compact body length of 10–12 cm and a dense, coarse grey‑brown coat.
How can a Dambo rat be differentiated? - in detail
The Dambo rat can be distinguished from other murid species through a combination of external morphology, cranial measurements, dental patterns, pelage characteristics, and genetic markers.
External morphology includes a relatively elongated body, a tail length that matches or slightly exceeds head‑body length, and hind feet with well‑developed plantar pads. The ears are proportionally small, set low on the skull, and lack the prominent auricular folds seen in many related taxa. Body weight ranges from 45 to 70 g in adult specimens, positioning it between the smaller Rattus rattus and larger Rattus norvegicus.
Cranial features provide reliable diagnostic criteria. The skull exhibits a narrow rostrum, a pronounced interorbital bridge, and a reduced auditory bullae compared with sympatric species. Measurements such as condylobasal length (≈ 38 mm) and zygomatic breadth (≈ 12 mm) fall within a narrow interval that separates the Dambo rat from congeners. The molar occlusal pattern shows shallow enamel folds and a distinct anterocone shape, distinguishable under a stereomicroscope.
Pelage analysis reveals a dorsal coat of coarse, dark brown guard hairs interspersed with lighter underfur, while the ventral surface is uniformly pale gray. The hair shaft diameter averages 45 µm, and the guard hair length reaches up to 12 mm, a combination uncommon in overlapping rodent communities. The presence of a faint, longitudinal stripe along the spine is a consistent field marker.
Genetic differentiation relies on mitochondrial cytochrome b sequencing and nuclear microsatellite profiling. The cytochrome b haplotype exhibits a unique 2.3 % divergence from the closest Rattus species, and specific microsatellite alleles at loci R12 and R27 are fixed within Dambo rat populations. Polymerase chain reaction (PCR) amplification of these loci, followed by capillary electrophoresis, yields a reproducible genotype pattern.
Practical identification in the field can follow this checklist:
- Body length and tail proportion matching or exceeding head‑body length.
- Small, low‑set ears without auricular folds.
- Narrow skull with reduced auditory bullae; specific cranial measurements.
- Dorsal guard hairs dark brown, ventral fur pale gray, with a faint dorsal stripe.
- Mitochondrial cytochrome b sequence showing > 2 % divergence from related taxa.
- Presence of diagnostic microsatellite alleles at R12 and R27.
Applying these criteria in combination provides a robust framework for reliably separating the Dambo rat from other rodent species across its geographic range.