Trioceros affinis ( Rueppell , 1845)

Koppetsch, Thore, Necas, Petr & Wipfler, Benjamin, 2021, A new chameleon of the Trioceros affinis species complex (Squamata, Chamaeleonidae) from Ethiopia, Zoosystematics and Evolution 97 (1), pp. 161-179 : 161

Trioceros affinis ( Rueppell, 1845)

Material examined.

Lectotype: SMF 16402 , adult male; origin: ‘Abyssinia’; collected by E. Rüppell, 1834; designated by Mertens (1967) (Fig. 1A-C ).

Paralectotype: SMF 16403 , adult female, same collection data as the lectotype (Fig. 1D-F ) .

Re-description of the lectotype.

The adult male lectotype ( SMF 16402) of Trioceros affinis is a small-sized and slender chameleon without outstanding ornamentation on the body and head. It has a total length of 148.3 mm (snout-vent length of 68.9 mm and a tail length of 79.4 mm) (Fig. 1A ). The tail is slightly longer than the rest of the body (RTL 0.54), heavily thickened at the base due to the presence of hemipenes situated in their pockets. The extremities are thin, the hind legs are slightly wider in diameter but equal in length.

The head is relatively short and blunt (HW/HL 0.52) with a low casque (RCH 0.85) merely exceeding the level of the neck (RCN 0.2). The head surface is covered with slightly enlarged flattened scales, which are more convex and slightly rugose between the canthi rostrales (Fig. 1B, C ; see Suppl. material 3: Dorsal head views). The head crests, typical for the genus Trioceros , are well developed and ornamented with slightly enlarged, convex scales. The canthus lateralis is well developed in all its parts. It starts with two paramesial scales on each side of the head, builds a margin of the low casque, continues as slightly less expressed supra-ocular crest with a more warty appearance on the canthus rostralis, which conjoin just above the tip of the snout forming a low ridge. The parietal crest consists of 5 scales merely larger than the surrounding ones, building a faint yet sharp medial ridge on the top of the casque. The temporal crest, consisting of 6 enlarged scales is expressed as a lateroventral emargination of a rugose triangular field below the lateral crest just behind the orbit and posterodorsally from it. It reaches the canthus lateralis proprius at about half of its length where it fuses with it. There are 16 upper labials and 16 lower labials on both sides of the head. The eye turrets are covered with a granular homogeneous scalation. The nostril is situated at half distance between the tip of the snout and rostroventral margin of the orbit. The body is covered with subhomogenous scalation, the standard scales are convex, not flat, of sub-circular or sub-oval form and of approximately same size all over the body, tail and extremities, with a tendency to become smaller ventrally towards the midventral line and on the distal part of the tail towards the tail tip. On the flanks, they are ordered in more or less longitudinal or diagonal long fields (running in craniodorsal-caudoventral orientation) that are grouped in rows of two (rarely three) scales. Here no interstitial skin is exposed, with the exception of the gular region, where lateroventrally, an inconspicuous groove can be observed between the slightly enlarged, spindle-shaped scales. There is one irregular, interrupted line of 8 significantly enlarged lenticular scales (the largest ones are about 3 times longer and 2 times wider than the surrounding standard scales). These scales are separated from each other by 3-7 standard scales, oriented longitudinally at about 2/3 of the body height and range from the shoulder to the pelvic region.

Anteriorly, the dorsal crest runs posteriorly of the casque, extending as a continuous well-developed, but low, crest consisting of conical scales of about double width and double height compared to the surrounding standard scales. The dorsal crest reaches in its described form the level of the groin, decreasing in height and formed by smaller subconical scales up to the first 1/4 of the tail with a more inconspicuous appearance. Dorsolaterally on both flanks, the first line of scales bordering the dorsal crest is slightly enlarged.

The gular crest is absent, instead, a rather narrow triangular field scattered with significantly smaller granular scales is present and ranges from the mentum to the arch of the hyoid. The ventral crest consists of a slightly enlarged, midventral line of scales ranging from the shoulder to the frontal margin of the cloacal fissure, which is separated into two parallel rows just along the umbilical scar, and ends at the ventral part of the tail.

Detailed meristic and mensural measurements of the lectotype are given in Table 1 and in the Suppl. material 2: Individual mensural and meristic measurements.

Coloration in preservative.

The animal is more or less uniformly greyish beige all over the body without any conspicuous pattern. Only a slight yellow hue can be found midventrally on the body, tail and the soles. The top of the head is slightly brownish. The claws are brownish yellow. Some prominent scales in the head region have a blackish centre, probably as a result of a mechanical bruise.

Variation.

The adult gravid female paralectotype ( SMF 16403) (Fig. 1D-F ) shows only minor morphological differences compared to the male lectotype. It has a lower total length (TL 146.0 mm) and longer tail (RTL 0.50). Also, it has a relatively higher casque (RCH 0.89) (Fig. 1E, F ). Both for the upper and lower labials 19 are present. 56 flank scales at midbody are present (vs. 54 in the lectotype) and a slightly lower number of scales forming the dorsal crest can be found (49 vs. 53 in the lectotype). The canthus parietalis is formed by only 3 scales. In contrast to the lectotype, the entire head region is coloured whitish without any brownish hue.

Detailed meristic and mensural measurements of the paralectotype are given in Table 1 and in the Suppl. material 2.

Based on our comparative examination of T. affinis specimens from different regions of Ethiopia, the lectotype material can be clearly assigned to populations west of the Ethiopian Rift. Individuals from south-western Ethiopia showed a lower body length compared with the lectotype material. Compared to the lectotype material, single individuals from Addis Abeba showed a more heterogeneous scalation on parts of the flanks by having single lateral scales that are enlarged more than 1.5 times compared to the surrounding scales. However, this heterogeneous scalation is not as prominent and extensive as in individuals of the northern Bale region. Actually, the latter were clearly distinct from other T. affinis specimens, which in the following is shown by significant statistical support and conspicuous differences in other diagnostic characters.

Justification for a new species of Trioceros based on statistical analyses.

According to our PCA analysis based on the morphological examination of the lectotype material of T. affinis as well as T. cf. affinis specimens from various localities in Ethiopia the first three components (those obtained through Broken Stick analysis) explained 24%, 17%, 10% of the total variation respectively). The first component was clearly discriminative between the species (Fig. 5 ; see Suppl. material 4: PCA Axis 1 vs. Axis 3 and PCA Axis 2 vs. Axis 3). The highest loadings for the first component referred to the continuous variables SDC, PEL, SCP and the categorical variables EDCS, HBS and RHS (Suppl. material 1: PCA loadings). Based on this component the new species has a lower number of SDC, a longer PEL and a higher number of SCP than T. affinis . Also, the new species has the exclusive characters EDCS, HBS and RHS, while none of the T. affinis individuals did. The first axis did not separate different sexes in any of the species. The lectotype and paralectotype of T. affinis show no significant differences to individuals of other populations included in our statistical analyses. Even though only the first principal component showed clear shape separation among the studied species, we still used all 3 meaningful components in the Per-MANOVA analysis. Based on Per-MANOVA the two species were significantly different from each other (F = 43.7, p = 0.0001).

According to the extensive morphological investigation of both the lectotype material of Trioceros affinis sensu stricto and individuals of T. affinis from other locations in Ethiopia, and the significant statistical distinctness of our new species from all the other T. affinis , we here formally describe Trioceros wolfgangboehmei sp. nov.

Figures

Figure 1. The preserved male lectotype (SMF 16402) (A.) and female paralectotype (SMF 16403) (B.) of Trioceros affinis collected by E. Rueppell 1834 and designated by Robert Mertens. Head morphology: Head of the lectotype in left (C.) and right (D.) view and of the paralectotype in left (E.) and right (F.) view. Scale bars represent 1 cm. Photos by Morris Flecks.

Figure 5. Principal component analysis (PCA) of morphological differences between Trioceros affinis (lectotype / paralectotype / males / females / juveniles) and T. wolfgangboehmei sp. nov. (male / females). Principal component axes refer to the first two principal components.