Trioceros wolfgangboehmei, Koppetsch & Nečas & Wipfler, 2021

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 wolfgangboehmei sp. nov.

Material examined.

Holotype: ZFMK 84811, adult male, Dinsho (3,130 m a.s.l. / 7°06'10"N, 39°47'25"E), Bale Mountains , Ethiopia, collected by Petr Nečas on the 6. August, 2004 (Fig. 2A, C, D ).

Paratypes: ZFMK 84812, adult female, with the same locality and collecting data as the holotype; ZFMK 84813, adult female, Goba (2,740 m a.s.l. / 7°00'36"N, 39°57'28"E), Bale Mountains , Ethiopia collected by Petr Nečas on the 7. August, 2004 (Fig. 2B, E, F ); ZFMK 63063, adult female, 10 km from Goba (2700 m a.s.l.), Bale Mountains, Ethiopia collected by Colin Tilbury in October 1996 .

Diagnosis.

Trioceros wolfgangboehmei sp. nov. is a small-sized chameleon of the Trioceros affinis species complex (sensu Ceccarelli et al. 2014). It can be distinguished from all other members of the same species complex by the following combination of characters:

(1) presence of a prominent and well-developed dorsal crest consisting of a relatively low number of significantly pointed and enlarged conical scales, forming a single row and reaching along the anterior half the tail;

(2) top of the casque posteriorly raised above the dorsal crest;

(3) heterogeneous body scalation with both small scattered standard scales and enlarged flattened plate-like scales;

(4) long canthus parietalis formed by 9-12 slightly enlarged scales;

(5) rugose head scalation consisting of enlarged scales forming the cranial crests that fill the area between the lateral and temporal crest and the posterior rim of the orbit;

(6) relatively high number of flank scales at midbody (53-59);

(7) relatively short snout-vent length (up to 66 mm);

(8) a unique hemipenial morphology including shallow calyces with smooth margins on the truncus, four pairs of thick, pointed and thorn-like papillae and two pairs of non-serrated rotulae.

Description of the holotype.

The adult male holotype ( ZFMK 84811) of Trioceros wolfgangboehmei sp. nov. is a small-sized chameleon with a total length of 156.3 mm (snout-vent length of 65.3 mm and a tail length of 91.0 mm) (Fig. 2A ). The head is relatively short, 18.9 mm long (HW/HL 0.54). The head scalation is rugose consisting of enlarged scales forming the cranial crests and filling the area between the lateral and temporal crest and the posterior rim of the orbit (Fig. 2C, D ; see Suppl. material 3: Dorsal head views). The top of the casque is raised posteriorly above the dorsal crest. Nine convex, enlarged and tubercular scales form the parietal crest. The casque is 11.7 mm high (RCH 0.91) and exceeds the dorsal crest on the neck by 3.2 mm (RCN 0.25). The parietal crest is 9.2 mm long. The temporal region is covered by prominent enlarged scales of larger size than the standard scales on flanks and limbs. The gular crest is absent in preserved specimens - in life, it is visible as two parallel paramesial skin folds on the throat. The temporal crest is weakly expressed; it is present merely as the caudodorsal emargination of the triangular temporal field of enlarged scales, described above. No gular grooves are present on the throat. The scalation on the eye turrets consists of granular scales, gradually slightly enlarged towards the eye opening. The supraorbital crest is formed by a single row of enlarged, pointed and sub-conical scales. Supralabials 16, infralabials 17. Between the supra-orbital crests, 12 inter-orbital scales, including crest scales, are present.

The prominent and well-developed dorsal crest consists of a relatively low number (37) of significantly pointed and enlarged conical scales, forming a single row and reaching along the anterior half of the tail as a prominent tail crest. The size of the dorsal crest scales is gradually decreasing posteriorly. The ventral crest is indicated by slightly enlarged conical scales forming a white midventral line.

The body scalation is heterogeneous and consists both of small scattered standard tubercular scales and, across the flanks, but especially dorso-laterally, enlarged flattened lenticular scales. The ventral regions of limbs and tail are covered by a fine granular sub-homogeneous scalation. No tarsal spurs are present on the hind-feet, toes terminate in a single, white claw and the soles of the extremities are smooth.

The hemipenes are everted and illustrated in asulcal, lateral and sulcal view with the apex on top (Fig. 4D-F ). On the asulcal side of the truncus, shallow calyces with smooth margins are present. The most prominent calyces are located on the distal aspect of the asulcal side. The sulcal lips covering the sulcus spermaticus are partially relatively smooth. Two pairs of unserrated rotulae are located on the apex, with the asulcal pair being of slightly larger size. On the sulcal side, four pairs of thick pointed and thorn-like papillae are arranged in a row between the rotulae. The papillae distally to the rotulae are the largest, the proximal ones are the smallest. Mensural and meristic data on the holotype are shown in Table 1 .

Colouration in life.

The ground body colour of living specimens of Trioceros wolfgangboehmei sp. nov. is yellowish, brownish or even bright green and varies in different individuals (Figs 6 , 7 ). Most specimens show a prominent bright white temporal spot posterior of the orbit formed by enlarged flattened scales (Figs 6 , 9 ). A dorso-lateral bright white or slightly orange longitudinal stripe can be found in many individuals. This dorsolateral stripe often is continuous, spreading along the flanks, but can be interrupted and form a Y-shaped pattern laterally (Fig. 8 ). This dorso-lateral pattern is corresponding with the occurrence of enlarged and flattened scales. The colour of the dorsal crest only slightly differs from the background colouration by being a little bit darker or brighter. A white stripe is present on the weakly expressed ventral crest. The throat region is usually of lighter colour in comparison to the ground colour. In some specimens, a beige ground pattern with slight reddish stripes can be found in the head region around the orbit. It ranges from dorsal to the nostrils around the entire eye turret to the casque and is bordered posteriorly by the temporal crest (Fig. 7 ). The limbs exhibit the same colour as the body, though they are coloured beige or yellowish medially.

Colouration in preservative.

The male holotype shows a dark, blackish body colouration, except on fore- and hindlimbs, the dorsal part of the tail, the posterior head region and the throat, which are of pale whitish colour (Fig. 2A ). A white midventral crest reaches from the throat to the cloaca. In the female paratypes, the more or less interrupted, sometimes Y-shaped, dorsolateral stripe is coloured orange, and also a whitish temporal spot or at least indistinct whitish colouration beyond the orbit can be recognised (Fig. 2B ).

Variation.

Variation in mensural and meristic characters for the adult type series is shown in Table 1 . The female paratypes of Trioceros wolfgangboehmei sp. nov. show only slight differences in snout-vent length (ranging from 59.7 mm to 65.8 mm vs. 65.3 mm in the male holotype). Females show a slightly lower relative tail length (ranging from 0.54 to 0.56 vs. 0.58 in the male holotype) as well as a lower head width/head length ratio (ranging from 0.51 to 0.53 vs. 0.54 in the male holotype). In the female paratypes, only 11 (vs. 12 in the holotype) inter-orbital scales between the supraorbital crests are present. Some female specimens show a longer parietal crest (PCL/SVL ranging from 0.15 to 0.19) compared to the male holotype (PCL/SVL 0.14).

The female paratypes show a variable dorsolateral colouration (Fig. 2B ) by having an orange coloured, more or less interrupted, sometimes Y-shaped, dorsolateral stripe (Fig. 8 ). In addition, the temporal light spot is more prominent and coloured white or orange (Figs 6 , 9 ).

Field observations of juvenile specimens around Goba show that the characteristic heterogeneous body scalation of adults (Fig. 8 ) can be clearly recognised already at early age (Fig. 10 ). Juveniles are uniform reddish brown with a slightly lighter gular and ventral regions.

Comparisons.

Trioceros wolfgangboehmei sp. nov. can be distinguished by a unique combination of morphological features from the other representatives of the genus Trioceros occurring in Ethiopia (see the key to the Ethiopian Trioceros provided below). It can be separated from T. bitaeniatus by lacking a midventral gular crest composed of conical scales; the absence of a dorsal crest with isolated groups of 3-5 enlarged scales; the lack of a low but prominent parietal crest and in not showing two longitudinal rows of enlarged flattened scales on the flanks forming a pair of lateral stripes differentiated in colour. Also, T. harennae differs from the newly described species by possessing a single gular crest that is conspicuously well-developed and formed by long, sometimes even laterally flattened scales. T. balebicornutus can be distinguished by a conspicuous gular crest and the shape and arrangement of the rostral scales. Males have a pair of rostral horns, while females show a pair of rostral pointed conical scales (or rugose and prominently enlarged warty scales in some females).

The new chameleon Trioceros wolfgangboehmei sp. nov. shows the closest morphological resemblance to T. affinis and is considered as a member of the T. affinis species complex (sensu Ceccarelli et al. 2014). Also, previous phylogenetic analyses revealed that populations of T. affinis from Addis Abeba show about 5% sequence divergence in the genetic marker ND4 (NADH dehydrogenase subunit 4) compared to individuals from the type locality of T. wolfgangboehmei sp. nov. ( Ceccarelli et al. 2014).

T. affinis sensu stricto, as defined by the lectotype specimen (Fig. 1 ), differs from T. wolfgangboehmei sp. nov. by having a less prominent dorsal crest consisting of a relatively higher number of smaller conical scales reaching to the base of the tail, a flat casque not raised above the level of the dorsal crest, no rugose and only slightly enlarged scales on the head and by showing a shorter canthus parietalis formed by a lower number of slightly enlarged scales. Although the new species shares single characters, but not in combination with each other or the exclusive scalation patterns described above, with some T. affinis populations e.g. from south-western Ethiopia, like a heterogeneous body scalation, relatively high number of flank scales at midbody and a relatively short snout-vent length, these characteristics are useful when distinguishing between new species and T. affinis specimens without precise indication of origin.

Concerning its hemipenial morphology, Trioceros wolfgangboehmei sp. nov. is distinct from T. affinis , which shows serrated rotulae (also present in T. balebicornutus ) and slightly deeper calyces (Fig. 4 ).

Etymology.

The specific epithet honours Wolfgang Böhme, senior herpetologist at the Zoological Research Museum Alexander Koenig in Bonn, Germany, for his numerous contributions to research on chameleons, for his outstanding and ongoing herpetological research in general, and, last but not least, for his continuously generous support of the first as well as second author and numerous junior zoologists. The species epithet is a noun in the genitive case.

Distribution and natural history.

Trioceros wolfgangboehmei sp. nov. is only known from the region around Dinsho and Goba in south-central Ethiopia. Those two villages are located directly in the Bale Mountains. The new species appears to be restricted to this area and can be considered as another endemic for the Bale Mountains. Trioceros wolfgangboehmei sp. nov. is not occurring syntopically with the two other Trioceros species distributed in the Bale Mountains, T. harennae or T. balebicornutus , which are confined to their southern slopes.

Trioceros wolfgangboehmei sp. nov. naturally occurs on the northern and north-eastern slopes of the Bale Mountains, Ethiopia. It was found at 3,130 m a.s.l. ( Nečas, pers.obs.) as well as at altitudes around 2,700 m (Tilbury 1998), but they might well climb higher within the National Park areas, and, they drop lower, living in the city centres of Goba (2,750 m a.s.l.) and Robe (2,500 m a.s.l.) and even in the northern suburbs of Robe around 2,400 m a.s.l. ( Nečas, pers. obs.). They are typical forest-edge inhabitants, not entering continuous forest zones. The perch height was recorded to reach from 0.7 m to 2.1 m above ground for the adults, with the majority of animals found at 1 to 1.5 m height, despite the possibility to climb higher. Juveniles tend to stay lower; they were recorded between 0.3 and 1 m high. Two predation records were made, a domestic cat and Somali Shrike ( Lanius somalicus Hartlaub, 1859) ( Nečas, pers. obs.).

Trioceros wolfgangboehmei sp. nov. prefers to live on small trees and bushes; juveniles can be found in grass, but always adjacent to trees and bushes. They are absent from large monoculture fields, while they form quite dense populations in traditional small fields and gardens. Based on field surveys and observations, the population density was estimated in 2004 to be even lower in the natural habitats within the National park (ca. 20-40 individuals per hectare) compared to surrounding gardens and local farms areas (ca. 80-110 individuals per hectare) ( Nečas, pers. obs.). The reason for higher densities in disturbed habitats is, that the living fences between fields and gardens are actually simulating the natural habitat: forest edge in much higher density, than under natural conditions, where they seem to be confined either to the real forest edge or microbiotopes at clearings, along water streams etc. This phenomenon is common for some other Afromontane species, confined to forest edge.

Conservation status.

The currently known distribution range of Trioceros wolfgangboehmei sp. nov. is restricted to a small region on the northern slopes of the Bale mountains. A part of the population is well protected within the Bale Mountains National Park, but another part is living outside, in the agriculturally used areas and even in gardens and remnants of vegetation in the local villages ( Nečas, pers. obs.). The man-modified landscape and a traditional way of agricultural land usage can have a positive impact on the abundance of chameleon populations, with occasionally higher densities in rural than in pristine areas. Their dependence on the forest is indirect, as they are evidently a forest edge species. Habitat destruction and fragmentation might be caused particularly by urbanisation, fires, monocultures, deforestation, aridisation and, in urban areas, increased predation by carnivores such as domestic cats. Chameleons, in general, are especially threatened by transformation of their habitats since their dispersal abilities to access and spread in new areas are limited and often they are highly adapted to well-defined ecological and climatic conditions. Due to its small distribution range and restricted area of occupancy on the one hand, but partially profiting from human-induced habitat changes on the other, it is likely that Trioceros wolfgangboehmei sp. nov. would be threatened. However, the species and its distribution remain insufficiently known, since - apart from our field observations - robust data concerning its conservation status are missing.

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 2. The preserved adult male holotype (ZFMK 84811) from Dinsho (A.) and adult female paratype (ZFMK 84813) from Goba (B.) of Trioceros wolfgangboehmei sp. nov. Head morphology: Head of the holotype in left (C.) and right (D.) view and of the paratype in left (E.) and right (F.) view. Scale bars represent 1 cm. Photos by Thore Koppetsch.

Figure 4. Volume renders of the µCT scans of the hemipenes of Trioceros affinis (ZFMK 54264) (A-C.) and the holotype of Trioceros wolfgangboehmei sp. nov. (ZFMK 84811) (D-F.) in asulcal (left), lateral (middle) and sulcal view (right) with the apex on top. ro - rotulae; pa - papillae; ca - calyces.

Figure 6. Living individual of Trioceros wolfgangboehmei sp. nov. from Dinsho, Ethiopia showing a prominent white temporal spot and dorsolateral longitudinal stripe. Photo by Petr Necas.

Figure 7. Living individual of Trioceros wolfgangboehmei sp. nov. from Goba, Ethiopia, showing a beige ground pattern with slight reddish stripes in the head region around the orbit. Photo by Petr Necas.

Figure 8. Lateral detail of a living Trioceros wolfgangboehmei sp. nov. from Goba, Ethiopia, showing the heterogeneous body scalation with both small scattered tubercles and enlarged flattened plate-like scales. In this individual the dorsolateral stripe is interrupted and forms a Y-shaped pattern on the flanks. Photo by Petr Necas.

Figure 9. Head of a living Trioceros wolfgangboehmei sp. nov. from Goba, Ethiopia. Photo by Petr Necas.

Figure 10. Living juvenile of Trioceros wolfgangboehmei sp. nov. from Goba, Ethiopia. Photo by Petr Necas.