Mesoamericus, Schools & Hedges, 2021

Schools, Molly & Hedges, S. Blair, 2021, Phylogenetics, classification, and biogeography of the Neotropical forest lizards (Squamata, Diploglossidae), Zootaxa 4974 (2), pp. 201-257 : 240

Genus Mesoamericus gen. nov.

Central American Forest Lizards

Fig. 27

Type species. Celestus bilobatus O’Shaughnessy, 1874:257 .

Diagnosis. Species of Mesoamericus gen. nov. have (1) claw sheath, present, (2) contact between the nasal and rostral scales, present, (3) scales in contact with the nasal scale, six, (4) postnasal scales, two, (5) position of the nostril in the nasal scale, posterior, (6) keels on dorsal body scales, absent, (7) digits per limb, five, (8) longest toe lamellae, 11–18, (9) dorsal scale rows, n/a (10) relative head width, 12.0–14.0, (11) relative rostral height, 65.0– 67.0, (12) relative frontonasal length, n/a, (13) relative interparietal distance, n/a, (14) relative axilla-groin distance, n/a.

From Siderolamprus , we distinguish Mesoamericus gen. nov. by the claw sheath (present versus absent in Siderolamprus ) and relative rostral height (65.0–67.0 versus 44.7–63.9).

Content. One species ( Table 3 ): Mesoamericus bilobatus .

Distribution. Mesoamericus gen. nov. occurs in Central America ( Nicaragua, Costa Rica, and Panama) ( Fig. 27 ).

Etymology. The generic name is a masculine noun derived from the name for the region (Mesoamerica) where it occurs.

Remarks. Mesoamericus gen. nov. is a monophyletic clade that has a support value of 100% in Bayesian and ML analyses ( Fig. 2 ). The large molecular divergence among populations of M. bilobatus , with some splits as old as 5 Mya ( Fig. 3 ), suggests the presence of three undefined species.

Figures

FIGURE 2. Phylogenetic tree of diploglossid lizards based on sequences of nine genes: four mitochondrial genes (CytB, ND2, 12S rRNA, and 16S rRNA) and five nuclear genes (AMEL, BDNF, PLPR, RAG1, and ZFP36). Maximum likelihood tree obtained from the nine-gene dataset (59 individuals; 6,949 sites).A scale bar indicates 5% sequence divergence. The numbers at nodes are ML bootstrap values, followed by Bayesian posterior probabilities; asterisks indicate significant (≥ 95%) support, and a dash or zero value indicates weak (<50%) support. The tree is rooted with Pseudopus apodus (Anguidae).

FIGURE 3. Timetree of Diploglossidae based on sequences of nine genes: four mitochondrial genes (CytB, ND2, 12S rRNA, and 16S rRNA) and five nuclear genes (AMEL, BDNF, PLPR, RAG1, and ZFP36). Nodes show divergence times in millions of years. A scale bar indicates time (6 million years ago, Mya). We show Bayesian credibility ranges as gray bars at nodes.

FIGURE 27. (A) In life image of Mesoamericus bilobatus (MHCH 2310, Cerro Mariposa, near Alto de Piedra, Veraguas, Panama). Photograph by Sebastian Lotzkat. (B) The distribution of Mesoamericus gen. nov. in Middle America.