A new species of Gnomidolon Thomson, 1864 and taxonomic and geographical notes on Hexoplonini (Coleoptera, Cerambycidae) from Colombia

. A new species of Gnomidolon from Colombia is described and illustrated: Gnomidolon franciscoi sp. nov.; and the previous key for the genus is modified to include the new species. The male of Gnomidolon hamatum Linsley, 1935 is described and illustrated for the first time. Additionally, a chromatic variation in some species of Hexoplonini from Colombia is reported and the geographical distribution of four species is expanded.


INTRODUCTION
The tribe Hexoplonini (Martins, 2006) is currently composed of 22 genera and 156 species (Tavakilian & Chevillotte, 2018), with geographical distribution restricted to Central (including the Caribbean) and South America (Bezark, 2019). In Colombia, the tribe is currently represented by four genera and 14 species (Botero, 2018).
The genus Glyptoscapus Aurivillius, 1899 differs from other genera of Hexoplonini in having a cicatrix at apex of scape; the third antennomere elongated; the prothorax smooth and without distinct constriction, and the elytra not distinctly depressed on central area (Martins, 2006;Nascimento & Santos-Silva, 2018). Currently, there are four Glyptoscapus species distributed in South America, and two species from Colombia (Botero, 2018).
In this work, a new species of Gnomidolon is described; the male of G. hamatum is described and illustrated, some chromatic variations are re-ported for Gnomidolon bellus Martins & Galileo, 2002 and Glyptoscapus pallidulus (White, 1855) and the geographical distribution of four species is expanded. Additionally, the key proposed by Martins (2006) for Gnomidolon is modified to include the new species described herein.

MATERIAL AND METHODS
The material examined was obtained in the Caribbean region of Colombia, in the Reserva La Flecha (RLF), Bolívar and the Reserva Campesina la Montaña (RCM), Atlántico (fragments of tropical dry forest). These locations were sampled from February to June 2018 by using a UV light trap, white light trap, manual capture and beating sheet. The sampling was supplemented by visits to entomological collections.
The material currently resides in the following institutions, which are subsequently referred to by their acronyms: Photographs were taken with a Canon EOS Rebel T3i DSLR camera, Canon MP-E 65 mm f/2.8 1-5X macro lens, controlled by Zerene Stacker focus stacking software. Measurements were taken in "mm" using the software Leica Application Suite (LAS 4.0) and the Leica M125 stereomicroscope, also used in the study of the specimens. References and geographical distributions were ascertained in Martínez (2000), and Monné (2018) and Tavakilian & Chevillotte (2018) catalogs. Remarks: Glyptoscapus pallidulus was initially described by White (1855) in the genus Ibidion, without mention the presence of a cicatrix in the apex of the scape (Nascimento & Santos-Silva, 2018), a characteristic only present in two genera of Hexoplonini (Glyptoscapus and Glyptoceridion Martins, 1959). Thirteen years later, Lacordaire (1868) placed this species in Gnomidolon and then, Martins (1967) transferred it to Glyptoscapus, where is currently allocated. Recently, Nascimento & Santos-Silva (2018) synonymized Glyptoscapus vanettii (Martins, 1959) and G. cicatricosus (Aurivillius, 1899) with G. pallidulus, as they identified it is an extremely variable species. According to Nascimento & Santos-Silva (2018) the variable characteristics are: "the general coloration, color of the head and pronotum, length, ratio and shape of spines of meso-and metafemora, number of rows of the elytra setae, etc. " Specimens of G. pallidulus from Colombia were examined and compared with several specimens from the MZSP, and other chromatic variations in this species were noticed, complementing the variability currently known. The Colombian specimens (Fig. 1A) have darker legs, femora brown (mainly meso-and metafemora) and tibiae dark brown (mainly meso-and metatibiae); also, antennomere III is dark brown at anterior half, darker than other specimens (Fig. 1B). Currently, the species is recorded from the department of Magdalena in Colombia, so the geographical distribution is expanded to the department of Bolívar. Remarks: Gnomidolon bellus was described by Martins & Galileo (2002) based on two males from Colombia (Tolima). The authors described the integument color as reddish on the prothorax and anterior fifth of elytra. I compared a few specimens from Colombia (from the Caribbean region) with a paratype deposited at the MZSP ( Fig. 1C) and noticed that the Caribbean specimens are darker: head, prothorax and anterior half of the elytra black ( Fig. 1D), which is considered a chromatic variation as there are no morphological differences between the specimens examined. Currently, this species was only known from the department of Tolima, thus I am registering it for the first time from the department of Atlántico and Bolívar in Colombia.

Gnomidolon franciscoi sp. nov. (Figs. 1E-1H)
Description: Female: Integument reddish, darker in some areas. Pedicel, antennomere III, and legs black. Antennomere IV-XI light brown, lighter toward apex of antennae. Elytra reddish; each elytron with a black curve band, beginning at middle of anterior fifth, from outer margin toward sutural margin and backing toward outer margin reaching middle of elytron; together both black bands form a "X", each black band surrounds a pale yellow area; below black band there is a pale yellow area and then a reddish area; elytral apex pale yellow, surrounded by a fine black line anteriorly.  Legs: Pro-and mesofemora subfusiform, metafemora cylindrical; with sparse long, erect setae. Mesofemoral apices projected in spicule at outer margin and with a spine at inner margin; metafemoral apices with small spicule at inner margin and long spine at outer margin, 1.9 times length of pedicel. Tibiae carinate (mainly mesoand metatibiae); with sparse long, erect setae, denser toward apex. Metatarsomere I slightly shorter than II-III together.
Abdomen: Ventrites laterally pubescent; with sparse long, erect setae. Ventrite I subequal in length than II-III together. Apex of ventrite V rounded.
Variability: Some specimens have darker integument, being light brown. Antennae of female shorter. The antennae are lighter in one of the specimens (reddish). The ventral pubescence is sparser in some specimens. The black line that surrounds the apical pale yellow area in the elytra can be lighter or absent.

Measurements (in mm):
Holotype, female, total length (w/ spine): 10.9, prothorax length: 2.9, largest prothorac-  1C-1D), G. biarcuatum (White, 1855), G. musivum (Erichson, 1847) and G. rubricolor Bates, 1870 by the general pattern of elytra color, with an oblique band on each elytron, forming a "X" when together; the pale yellow area below the oblique band and the elytral apex pale yellow with a long outer spine. Gnomidolon franciscoi sp. nov. differs of G. bellus in having the legs and antennae black; the "X" black band extends reaching the external margin anteriorly; and a black line delimiting anteriorly the pale yellow area of the elytral apex (although this black line can disappear in some specimens). In G. bellus the pro-and mesolegs, the metatibiae, and the antennae are yellow; the "X" black band does not extend to the external margin anteriorly; and the black line above the pale yellow area in the elytral apex is absent. Gnomidolon franciscoi sp. nov. differs of G. biarcuatum in having dark femora; the "X" black band reaches the external margin anteriorly; and the anterior region of elytra reddish. Gnomidolon biarcuatum has the pro-and mesofemora yellow and the metafemora black; the "X" black band does not reach the external margin anteriorly; and the general coloration of elytra is yellowish. Gnomidolon franciscoi sp. nov. differs of G. musivum in having the elytral "X" band black and continuous; the legs and antennae black; and the outer spine of mesofemora projected. In G. musivum the elytral "X" band is pale yellow and discontinuous; the legs and antennae are reddish; and the mesofemora apex is not projected. Gnomidolon franciscoi sp. nov. differs of G. rubricolor in having the "X" black band backing toward the outer margin reaching the middle of the elytron; black femora; and having equal spines in the mesofemora. Gnomidolon rubricolor does not have the "X" black band backing toward the outer margin; the femora are light reddish; and the inner spine of mesofemora is more projected than the outer spine. Gnomidolon franciscoi sp. nov. is also similar to G. varians Gounelle, 1909 by having prothorax without microsculpture and longitudinal bands, the elytral apex pale yellow (in some specimens of G. varians) with a long outer spine and metafemora concolorous with pro-and mesofemora. Gnomidolon franciscoi sp. nov. differs from G. varians in having reddish integument; scape apex projected at outer margin; a "X" black band on elytra; dark antennae and legs. Gnomidolon varians have yellowish integument; scape subcylindrical; elytra without "X" black band; and antennae and legs yellow.

According to the key to species of Gnomidolon (Martins, 2006), the new species can be inserted as follows (translated and modified):
26 (25)    Thorax: Prothorax cylindrical, with parallel sides; 1.5 times longer than wide. Pronotal disk with 2 median smooth gibbosities. Surface of pronotum with dense, fine punctation and a few long, erect setae, except for gibbosities. Lateral sides of prothorax with same sculpture as pronotum. Prosternum glabrous on anterior margin, slightly striated with a transversal, fine line of short decumbent setae; remaining area with dense, fine sexual punctation. Prosternal process pubescent and narrow, divergent toward apex, apex truncate, width at narrowest point about 0.2 times of procoxal cavity width. Mesoventrite pubescent, tumid in area close to mesoventral process. Mesoventral process sparsely pubescent, emarginated on apex, width at narrowest point about half of mesocoxal cavity width. Mesanepisternum and mesepimeron densely pubescent. Metaventrite densely pubescent, except centrally with a few short decumbent setae interspersed with long erect setae. Metanepisternum pubescent. Scutellum sparsely pubescent, denser on apex; rounded at apex. Elytra densely and coarsely punctate on anterior half, finer toward apex; with long, erect setae aligned in three longitudinal rows, denser and irregularly aligned toward apex; each elytron with one oblique dark-brown band. Apex emarginated with long spine at outer angle, 0.8 times length of pedicel; and small sutural projection.
Legs: Femora cylindrical (mainly metafemora); with long, erect setae on inner face; apex of mesofemora with short spine at inner side; apex of metafemora with short spine at inner and outer side. Meso-and metatibiae carinate; with sparse long erect setae, denser toward apex. Metatarsomere I subequal in length than II-III together.