Xystochroma luteotarsis, Bezark & Santos-Silva, 2023

Bezark, Larry G. & Santos-Silva, Antonio, 2023, Expanding knowledge of American Cerambycidae (Coleoptera): new species, new records, and morphological variations, Papéis Avulsos de Zoologia 63, pp. 1-19 : 2-5

Xystochroma luteotarsis sp. nov. ( Fig. 1 )

Description: Holotype male ( Fig. 1 A-1E): Metallic green and blue areas alternating between them depending on the angle of incidence of light. Head capsule shiny metallic green and blue, except opaque, blackish macula on each side of upper eye lobes and dark brown posterior region of gulamentum; anteclypeus and labrum dark brown, with sides of labrum light- er; apex of sides of postclypeus and of the genae black; ventral mouthparts mostly light brown, except parts of mentum metallic green, maxillary palpomeres I-III mostly light brown with irregular yellowish brown areas,maxillary palpomere IV brown, and labial palpomeres dark brown with apex of I-II yellowish-brown apex.Mandibles shiny metallic green and blue, except black apical third. Antennae black, with slight violaceus reflections on some areas. Wide central area of pronotum blackish blue, from near anterior margin to posterior constriction, except longitudinal, shiny metallic green and blue band centrally; remaining surface shiny metallic green and blue. Most of sides of prothorax and about posterior ¾ of prosternum shiny metallic green and blue; anterior quarter of prosternum and part of posterior region of sides of prothorax dark brown. Prosternal process dark brown laterally, slightly shiny and greenish centrally. Ventral surface of mesothorax shiny metallic green and blue except dark brown margins of segments. Ventral surface of metathorax shiny metallic green and blue, except large, subtriangular posterocentral area on metaventrite. Scutellum shiny metallic green. Elytra blackish blue, except shiny metallic green longitudinal band close to suture, vaguely orange on posterior half, shiny metallic green longitudinal band laterally on dorsal surface, from humeri to near apex, irregular, less distinct close to humerus, irregular, less distinct, curved and subfused to sutural band apically, and narrow, shiny metallic green band close to anterior third of epipleural margin. Legs black, except orangish tarsi. Abdominal ventrites 1-5 shiny metallic green and blue, except dark brown large central area and apex of ventrites 1-3, and apex of ventrite 4; ventrite 6 shiny metallic blue laterally, more blackish blue depending on the angle of incidence of light, dark brown centrally.

Head ( Fig. 1D ): Inferior region of frons and postclypeus abundantly, finely punctate, except smooth sides of postclypeus; central region of frons slightly tumid, somewhat transversely rugose on each side of medi- an groove; sides longitudinally, widely, somewhat shallowly sulcate from before middle to base of antennal tubercles, carina-shaped from clypeus to antennal tubercles; central region sparsely, finely punctate; lateral sulcate area abundantly, minutely punctate; superior region densely, minutely punctate. Median groove distinct from near clypeus to area between antennal tubercles. Area between antennal tubercles, smooth, glabrous on each side of median groove, and densely, minutely punctate laterally; area between upper eye lobes with smooth, glabrous diamond-shaped area centrally, densely, minutely punctate, with abundant blackish pubescence laterally. Remaining surface with sculpturing and pubescence as sides of area between upper eye lobes, except abundantly, coarsely rugose-punctate, glabrous area close to prothorax. Area behind upper eye lobes with sculpturing and pubescence as on posterior region of vertex close to it, finely, sparsely punctate, glabrous close to eye toward inferior region, rugose-punctate, glabrous close to prothorax toward inferior region. Area behind lower eye lobes coarsely rugose-punctate, glabrous, except finely rugose-punctate, glabrous narrow area close to prothorax. Genae somewhat abundantly, finely punctate, glabrous on wide area close to eye, densely, minutely punctate, glabrous close to smooth apex. Antennal tubercles glabrous, densely, minutely punctate frontally, punctures gradually sparser toward posterior region, except smooth apex. Labrum coplanar with anteclypeus, except inclined anterocentral region; abundantly, finely punctate, except smooth area close to anteclypeus, sides, and anterocentral region; with long, erect brownish setae laterally, short, erect brownish setae anterocentrally, glabrous on remaining surface. Gulamentum ( Fig. 1B ) smooth, glabrous on center of posterior half, somewhat coarsely rugose, with a few brownish erect setae on sides of posterior half; anterior half coarsely, transversely rugose, with sparse punctures interspersed, and sparse, long, erect brownish setae. Distance between upper eye lobes 0.24 times distance between outer margins of eyes; in frontal view, distance between lower eye lobes 0.38 times distance between outer margins of eyes. Antennae 1.5 times elytral length, reaching elytral apex at base of antennomere XI. Scape ( Fig. 1E ) gradually widened toward apex; with subtriangular projection on outer apex; out- er side of dorsal surface, outer lateral surface, and ventral surface glabrous, sparsely, finely punctate, except smooth apex; inner side of dorsal surface densely, minutely punctate, with minute blackish setae. Pedicel somewhat abundantly, finely punctate; with short blackish setae, and somewhat long, erect black setae ventrally. Antennomeres III-XI with dense, minute blackish pubescence; antennomeres III-VI whit short, erect black setae on inner margin, and short, thick black setae on apex of ventral surface. Antennal formula (ratio) based on length of antennomere III: scape = 0.50; pedicel = 0.11; IV = 0.63; V = 0.67; VI = 0.67; VII = 0.62; VIII = 0.55; IX = 0.49; X = 0.46; XI = 0.64.

Thorax: Prothorax wider than long (including lateral tubercles); anterior and posterior constrictions well marked; lateral tubercles large, conical, with blunt apex, located centrally. Pronotum ( Fig. 1A ) with large, transverse gibbosity on each side of anterior half, somewhat transversely elevated close to posterior constriction, forming distinct plate laterally; with longitudinal, narrow sulcus centrally, from anterior margin to posterior constriction, more distinct after anterior constriction, very finely rugose-punctate, except smooth area close to middle of pronotum;blackish-blue area densely,minutely punctate, with dense, short blackish pubescence partially obscuring integument, except on longitudinal central sulcus; sides and posterior regions with a few minute punctures and a few minute dark setae. Sides of prothorax ( Fig. 1C ) with longitudinal gibbosity between anterior constriction and lateral tubercles; glabrous, sparsely, minutely punctate, except finely rugose-punctate area close to posterior margin. Prosternum densely, finely punctate, with dense grayish-white pubescence on posterior ¾, except somewhat rugose, glabrous anterocentral region; anterior quarter glabrous, transversely striate, except smooth area close to anterior margin. Prosternal process widely, longitudinal sulcate centrally on basal ¾; with dense grayish-white pubescence; narrowest area 0.3 times procoxal width. Mesoventrite, mesanepisternum, and mesepimeron densely, minutely punctate, punctures slightly sparser laterally; with abundant grayish-white pubescence not obscuring integument. Mesoventral process widely, longitudinally elevated centrally; parallel-sided; apex distinctly emarginate centrally; with abundant grayish-white pubescence; apex 0.77 times mesocoxal width. Metanepisternum and metaventrite with dense grayish-white pubescence, except glabrous dark-brown area. Scutellum longitudinally sulcate centrally; basal half densely, minutely punctate; posterior half somewhat rugose. Elytra: Densely, minutely punctate, with dense, minute dark pubescence, except longitudinal sutural green band glabrous, finely, transversely striate, outermost longitudinal green band on dorsal surface finely rugose-punctate, almost glabrous, and epipleural green band with abundant grayish-white pubescence. Legs: Profemora abundantly, minutely punctate dorsally, minutely, sparsely punctate on remaining surface; with somewhat abundant grayish-white pubescence dorsally, glabrous on remaining surface. Mesofemora densely, minutely punctate dorsally, slightly sparsser, minutely punctate laterally, mostly smooth ventrally; with somewhat abundant grayish-white pubescence dorsally, pubescence sparser on remaining surface. Metafemora densely, minutely punctate, except finely, slightly sparsely punctate on posteri- or of ventral surface, and apex of dorsal surface; with abundant grayish-white pubescence except sparse pubescence on areas with sparser punctures. Protibiae with sparse blackish pubescence on basal half of dorsal and lateral surfaces, and dense, bristly yellowish-brown pubescence on ventral surface and basal half of dorsal and lateral surfaces (yellowish-brown pubescence appearing to be blackish depending on angle of light source). Mesotibiae with sparse blackish pubescence basally, pubescence gradually denser, bristly, dark yellowish-brown toward apex,especially on apical third. Protibiae distinctly widened from basal quarter, laterally flattened; with abundant dark pubescence, blackish bristly dorsally and ventrally. Dorsal surface of tarsi with abundant yellowish-white pubescence not obscuring integument; metatarsomere I 1.4 times longer than II-III together.

Abdomen: Ventrites 1-5 with dense grayish-white pubescence except glabrous apex on ventrites 1-4, glabrous area distinctly wider on ventrite 4. Apex of ventrite 5 widely emarginate centrally. Ventrite 6 with sparse grayish-white pubescence laterally, pubescence denser on center of posterior ¾;apex distinctly emarginate centrally.

Female ( Fig. 1 F-G): Similar to male, differencing by the antennae ( Fig. 1F ) slightly shorter, 1.35 times elytral length, reaching elytral apex at posterior sixth of antennomere XI, and apex of ventrite 5 ( Fig. 1G ) slightly emarginate centrally. The longitudinal green central band on the pronotum (1F) is wider than in the holotype male, and the longitudinal shiny bands on the elytra are more orangish.

Dimensions in mm (holotype male/ paratype female): Total length, 22.30/26.80; prothoracic length, 3.90/4.35; anterior prothoracic width, 3.25/3.70; posterior prothoracic width, 3.80/4.40; maximum prothoracic width,5.35/6.00; humeral width, 5.85/6.70;elytral length, 16.10/18.60.

Type material: Holotype male from ECUADOR, Napo: Misahualli, nr. Tena , 06-19.X.2001, C. Brammer leg. ( CASC) . Paratype female, same data as holotype ( LGBC).

Etymology: The specific epithet luteotarsis refers to the striking coloration of the tarsi which separate this species from others in the genus.

Remarks: Xystochroma luteotarsis sp. nov. can be separated from the other species of the genus using the key adapted from Napp & Martins (2009):

1. Tarsi orangish. Ecuador................................... X.luteotarsis sp.nov.

— Tarsi black or at most basal area of tarsomere I lighter ...................2

2(1). Pro- and mesofemora entirely black or with metallic color.............3

— Pro- and mesofemora orangish or bicolorous.................................5

3(2). Sutural band on the elytra wide, distinct, with golden pubescence. Colombia......................................... X.setigerum (Schmidt,1924)

— Sutural band on the elytra narrow and glabrous ............................4

4(3). Metafemora with shiny metallic, green or blue; antennae in male surpassing elytral apex by 1.5 antennomeres; basal half of the pronotum with small shiny triangular area and remaining surface finely and uniformly punctate. Costa Rica, Panama, Colombia, Venezuela............................................. X.chloropus (Bates,1979)

— Femora black;antennae slightly surpassing elytral apex in both sexes;pronotum with shiny longitudinal central band, with or without transverse striae. Costa Rica, Panama, Venezuela................... .................................................... X.clypeatum (Schwarzer,1923)

5(2). Metafemora entirely orangish or orangish with the apex narrowly black...........................................................................................6

— Metafemora orangish with, at least, the apical third black or shiny metallic.....................................................................................11

6(5). Scape reddish. Mexico (Veracruz), Panama....................................... ........................................................ X.buprestoides (Bates,1885)

— Scape dark,often black ..................................................................7

7(6). Metafemora with carina on outer apical quarter............................8

— Metafemora without carina............................................................9

8(7). Sutural band on the elytra narrow; apex of the lateral tubercles of the prothorax acute;disc of the pronotum not rugose;antennomere III without carina. Brazil (Minas Gerais, Rio Grande do Sul)..... ............................................. X.femoratum Napp & Martins,2005

— Sutural band on the elytra wide;apex of the lateral tubercles of the prothorax blunt;disc of the pronotum transversely rugous;antennomere III carinate. Venezuela, French Guiana.............................. ............................................. X.incomptum Napp & Martins,2005

9(7). Sutural band on the elytra mostly glabrous. Panama, Colombia, Brazil (Distrito Federal, Rio de Janeiro, São Paulo, Paraná, Santa Catarina), Paraguay........................... X.bouvieri (Gounelle,1911)

— Sutural band on the elytra pubescent...........................................10

10(9). Ventral surface of meso- and metafemora abruptly narrowed near apex. French Guiana................... X.touroulti Juhel & Dalens,2017

— Ventral surface of meso- and metafemora not abruptly narrowed near apex. Brazil (Distrito Federal, Goiás, Minas Gerais, Espírito Santo, Rio de Janeiro, São Paulo, Paraná, Santa Catarina, Rio Grande do Sul)............................... X.neglectum (Gounelle,1911)

11(5). Inner side of apical third of the metafemora with arched spicules. Brazil (Rio de Janeiro, São Paulo).................................................. .............................................. X.echinatum Napp & Martins,2005

— Metafemora without arched spicules ...........................................12

12(11). Scape with apical projection dorsally; antennomere III carinate, sparsely pubescent. Brazil (Rio de Janeiro, São Paulo) .................. ................................................................. X.zikani (Zajciw,1965)

— Scape without apical projection; antennomere III not carinate, densely pubescent....................................................................13

13(12). Sutural band on the elytra often indistinct; metafemora slender, flattened, shiny metallic apically. Brazil (Goiás, Minas Gerais, Rio de Janeiro, São Paulo, Paraná) .............. X.gracilipes (Bates,1879)

— Sutural band on the elytra, narrow, distinct; metafemora cylindrical, black apically. Brazil (Minas Gerais, Rio de Janeiro, Santa Catarina).............................................. X.minutum (Zajciw,1965)

Note: the differences pointed out in the key to separate X. chloropus from X. clypeatum are questionable. Photographs of the holotypes of the two species suggest they are probably synonyms.

Figures

Figure 1. Xystochroma luteotarsis sp. nov. (A-E) Holotype male: (A) Dorsal habitus; (B) Ventral habitus; (C) Lateral habitus; (D) Head, frontal view; (E) Scape. (F-G) Paratype female:(F) Dorsal habitus;(G)Ventral habitus.