Lygodactylus rarus Pasteur & Blanc, 1973

Vences, Miguel, Multzsch, Malte, Gippner, Sven, Miralles, Aurélien, Crottini, Angelica, Gehring, Philip-Sebastian, Rakotoarison, Andolalao, Ratsoavina, Fanomezana M., Glaw, Frank & Scherz, Mark D., 2022, Integrative revision of the Lygodactylus madagascariensis group reveals an unexpected diversity of little brown geckos in Madagascar’s rainforest, Zootaxa 5179 (1), pp. 1-61 : 16-17

Lygodactylus rarus Pasteur & Blanc, 1973

Lygodactylus (Domerguella) rarus Pasteur & Blanc, 1973

Chresonyms:

Lygodactylus rarus: Kluge (1991) ; Glaw & Vences (1992, 1994, 2007); Puente et al. (2005, 2009); Röll et al. (2010); Gippner et al. (2021)

Lygodactylus (Domerguella) rarus: Rösler (2000b)

Name-bearing type: female holotype, MNHN 1990.6 —Type locality: “haute de la falaise orientale du karst d’Ambilobe (extrémité nord-est du Massif de l’Ankarana )”, according to the original description.—Other types: none according to original description.—Etymology: derived from Latin rarus (rare, unusual) .

Identity and Diagnosis. According to the diagnosis of Puente et al. (2009) this is a rather large-sized endemic of limestone karst areas of northern Madagascar, characterized by a long-legged, long-tailed and slender appearance. It differs from all species in the L. madagascariensis group by the presence of broad crossbands in the tail, of alternate light gray/brown color ( Figs. 9–10 ). Although other Domerguella also can have tail crossbands, these are usually irregular, typically with alternating sections which start light brown or beige, gradually become darker to end in a somewhat posteriorly concave narrow dark line that then posteriorly borders sharply on the next light portion. In contrast, the crossbands of L. rarus typically consist of alternating brownish vs. gray portions which rather sharply border at each other, the brown portions typically being broader than the gray portions ( Fig. 9 ). This typical pattern is also visible in the holotype which, upon examination in 2021, was in a quite poor state of preservation. The species also differs from all other Domerguella by the highest number of longitudinal ventral scales along the body (119–139, with 125 longitudinal ventral scales in the holotype; all other Domerguella have at most 110 ventral scales).

In addition, this species is also characterized by a particularly slender body and long limbs ( Fig. 10 ): relative hindlimb length (HIL/SVL) is 0.56–0.60 in L. rarus , vs. a maximum of 0.50 in all but one other Domerguella . The only other Domerguella species with long hindlimbs>0.5 is L. sp. 18, but also this species only reaches a ratio value of 0.54, thus shorter than in L. rarus .

The three diagnostic character states (tail crossbands, large number of ventral scales, long hindlimbs) are all recognizable in the holotype, and in the genetically characterized specimens collected by us. All these specimens were collected in the Ankarana Massif. Therefore, there is no doubt about the identity of L. rarus , and the molecular data herein can confidently be assigned to this species.

Furthermore, L. rarus is distinguished from L. miops and especially L. guibei by the absence (vs. presence) of dorsolateral tubercles and spiny tubercles at the tail base. It is further distinguished from the sympatric L. expectatus by its non-enlarged dorsolateral scales (vs. enlarged), absence of dark spots on the neck (vs. presence), and larger size (adult SVL 31.6–36.5 mm vs. 27.0– 29.7 mm).

Distribution. L. rarus is reliably only known from its type locality, the Ankarana Massif. Pasteur & Blanc (1973) also report the species from Mangindrano (located at 1300 m a.s.l. on the Tsaratanana Massif), based on two juveniles that hatched from eggs collected in an abandoned bird nest. We here consider this record as in need of confirmation, given the uncertain attribution of these two hatchlings.

Figures

FIGURE 9. Tails of preserved specimens of Lygodactylus rarus and six other species of the subgenus Domerguella for comparison. Note the very regular dark-light crossbands characterizing L. rarus, including the holotype. Not to scale.

FIGURE 10. Specimen of Lygodactylus rarus from Ankarana in life, photographed in 2003 (not corresponding to any of the morphologically examined voucher specimens).