Yumtaax laticornis (Truqui, 1857)

Beza-Beza, Cristian Fernando, Beck, James, Reyes-Castillo, Pedro & Jameson, Mary Liz, 2017, Phylogeny of the genus Yumtaax Boucher (Coleoptera, Passalidae, Proculini): Taxonomic and evolutionary implications with descriptions of three new species, ZooKeys 667, pp. 95-129 : 113-116

Yumtaax laticornis (Truqui, 1857)

Passalus laticornis Truqui, 1857: 262, 316.

Pseudacanthus laticornis (Truqui) [comb. n. by Kaup 1871: 72, 74].

Petrejoides laticornis (Truqui) [comb. n. by Reyes-Castillo 1970: 125].

Yumtaax laticornis (Truqui) [comb. n. by Boucher 2006: 348].

Material examined.

Holotype and 31 non-type specimens.

Holotype ♂. MEXICO: Jacale, 1708 ( Sallé) (BMNH).

Non-type specimens (31 total): 2 ♂, 20 ♀, 9 unknown. MEXICO: Veracruz, Calcahualco, Tecuanapa, bosque mesófilo, alt. 2200 m, VI 1992 ( Capistrán, Delgado) (IEXA; CFBB).

Diagnosis.

Yumtaax laticornis is a large (24.5-33.0 mm) brachypterous species and is part of the Yumtaax laticornis clade (Fig. 4). This species is diagnosed by the following character combination: the clypeus is vertical (shared with Y. veracrucensis , Y. cameliae ; inclined in other members of Yumtaax ) and the anterior border is straight (shared with other members of Yumtaax except for Y. recticornis and Y. olmecae with concave anterior border of clypeus); mesofrontal structure (MFS) of the “falsus” type (see Reyes-Castillo 1970) (shared with all members of Yumtaax except Y. cameliae which has the MFS of the “striatopunctatus” type), with the central tooth largely free (shared with Y. recticornis , Y. veracrucensis , Y. cameliae , Y. mazatecus ; fused with frontal ridges in Y. jimenezi , Y. imbellis , Y. nebulosus , Y. olmecae ), directed anteriorly (shared with Y. veracrucensis ; directed dorsally in Y. recticornis , Y. imbellis , Y. nebulosus , Y. olmecae ; directed dorsally and anteriorly in Y. jimenezi , Y. mazatecus ; elevated in the posterior half bending abruptly forward in the anterior half in Y. cameliae ), and reaching the frontoclypeal suture (shared with Y. veracrucensis , Y. cameliae ; not reaching the clypeus in other members of Yumtaax ); eyes are strongly reduced (shared with Y. mazatecus ; eyes large in Y. recticornis , Y. imbellis ; eyes moderately reduced in Y. veracrucensis , Y. cameliae , Y. jimenezi , Y. nebulosus , Y. olmecae ); and the scutellum is punctate (smooth in other members of Yumtaax ).

Dimensions

(mm) (n = 19). Total length 24.5-33.0 ( χ = 29.5); elytral length 14.0-17.5 ( χ = 16.5); pronotal length 6.0-9.0 ( χ = 8.0); pronotal width 8.0-11.0 ( χ = 10.0); humeral width 7.0-10.0 ( χ = 9.0).

Redescription of holotype

(Fig. 7). Head (Fig. 7C). Labrum: anterior border concave, dorsal surface smooth and glabrous medially, punctate and setose apicolaterally, apically, and basally; anterior edge excavated. Clypeus: vertical, rectangular, flat, shiny, and smooth. Frontoclypeal suture: straight, and shiny; external tubercles rounded weak, directed anteriorly. Frontal area: vertical, flat, smooth and shiny, frontal ridge absent. Frontal fossae: punctate and glabrous. Mesofrontal structure (MFS): of the “falsus” type (see Reyes-Castillo 1970); base subparallel and narrower than MFS’ lateral ridge; center horn long with apex acute, largely free and directed anteriorly (Fig. 7D), surpassing posterior margin of clypeus, dorsally without micro-punctures; base of center horn wide narrowing gradually until apex; dorsal fossa absent at the base of MFS. Occipital fossa: shallow posteriorly and deeper laterally, not connected with the frontal fossae. Posterior occipital sulcus concave. Supraorbital ridge: bituberculate, tubercles of similar size; posterior half of supraorbital ridge bifurcated. Canthus: with apex rounded, covering more than 1/3 of the eye, expanded distally. Eyes: strongly reduced (distal edge of the eye shorter than the distal edge of the canthus), width = 0.4 mm (each eye). Head width (between posterior tubercles of the supraorbital ridge) = 5.0 mm. Ratio of sums of both eyes widths/total head width = 0.16; postocular area punctate and setose. Ligula: tridentate, central tooth surpassing apex of lateral teeth, lateral teeth rounded; setose punctures present in discal area; posterior border straight. Mentum: lateral lobes rounded and wide, with setose punctures. Basomedial portion protruding ventrally; anterior border at middle straight; basal fossae present, with setose punctures. Hypostomal process: with lateral depression; separated from mentum by a distance larger than the wide of the anterior width of hypostomal process. Infraocular ridge (e.g., Fig. 3): short and wide anteriorly, narrow posteriorly. Mandible: with 3 apical teeth; internal tooth of left mandible bidentate; dorsal tooth occupies more than half length of the mandible. Pronotum: anterior angles rounded. Anterior fossae of marginal sulcus punctate. Lateral fossae without punctures. Marginal groove with punctures. Prosternum: opaque. Prosternellum with anterior half and lateral edges opaque and posterior half and middle area shiny. Scutellum: punctate and glabrous. Mesosternum: with anterior-lateral areas opaque. Metasternum: with setae anterolaterally, lacking punctures in lateral margins of the metasternal disc. Lateral fossae wide glabrous posteriorly with setose punctures anteriorly. Elytra: anterior border straight. Meeting point of striae 1-10 (see Reyes-Castillo 1970) with one line of punctures. Wings: reduced. Legs (Fig. 7E): femur I with longitudinal anteroventral groove strongly developed, reaching the distal end of the femur, posterioventral half pubescent; setae short, dense, reddish. Abdomen: last sternite with marginal groove complete (Fig. 7B). Aedeagus (Fig. 7F, G, and H) (Description based on non-type material): dorsal view phallus globose (wider than long). Ventral view lateral edges of the phallus surpassing the laterodistal edges of the parameres.

Variation.

The non-type material differs from the holotype in the following characters: internal tubercles obsolete to strongly developed; frontal ridges obsolete to strongly developed; frontal area glabrous to sparsely setose; ratio of eyes versus head width varies from 0.13-0.23; pronotum laterally with or without strong punctures, even at the individual level (right vs left side of the pronotum); prosternelum completely opaque or opaque and shiny.

Distribution.

This species is known from cloud forest (bosque mesófilo, 2200 m elevation) at Orizaba Peak, Veracruz, Mexico. In the original description, Truqui (1857) cited one specimen collected by Sallé from Jacal near the Orizaba Volcano. This locality corresponds to El Jacal, Coscomatepec, Orizaba Peak ( Reyes-Castillo 2011).

MEXICO: Veracruz: Calcahualco (Tecuanapa, road from Calcahualco to the Pico de Orizaba), Jacale, Pico de Orizaba.

Remarks.

Castillo and Reyes-Castillo (1984) redescribed Y. laticornis without examining type specimens. We compared two specimens of Y. laticornis determined by Castillo and Reyes-Castillo with the holotype specimen designated by M. E. Bachus at The Natural History Museum, London. Close examination of the holotype and results of the phylogenetic analysis (Fig. 4 and Suppl. materials 2-4) provide evidence that Y. laticornis is not conspecific with Y. laticornis sensu Castillo and Reyes-Castillo (1984) ( Y. LM in Suppl. materials 2-4). Specimens described as Y. laticornis by Castillo and Reyes-Castillo (1984) correspond with Y. cameliae sp. n. ( Y. LM in Suppl. materials 2-4), and the holotype of Y. laticornis corresponds with Y. CM (Suppl. materials 2-4). The overall length of the holotype specimen is 30.0 mm, and this falls within the size range for Y. laticornis (25.0-33.0 mm), but not within the range for Y. cameliae (22.5-25.5 mm). Furthermore, based on distribution and biogeography, Y. cameliae has been collected only in the type locality where suitable habitat for the species occurs. This area is geographically isolated from the distribution area of Y. laticornis . Yumtaax laticornis ' inclusion in the Y. laticornis clade (is strongly supported (PP 1.0/BS 100) (Fig. 4).