Chrysina occidentalis Robacker and Hawks, 2022

Robacker, David C., Hawks, David C., Castillo, Naidely & Miranda, Brianna, 2022, A new species of Chrysina Kirby (Coleoptera: Scarabaeidae: Rutelinae) from the Sierra Madre Occidental of Mexico, with notes on the type locality of Chrysina adelaida (Hope, 1841), Insecta Mundi 2022 (955), pp. 1-14 : 10-13

Chrysina occidentalis Robacker and Hawks , new species

Figures 4–5 , 10–11, 14, 16

Type data. Holotype ♂ (deposited at UNAM) labeled: a) “México: Sinaloa / El Palmito , elev. 7140′ / N 23° 35.116, W 105° 51.863 / 16 August 2007 / D. C. Robacker ”; b) “Sin 7”; c) on red paper, “ Chrysina occidentalis ♂ / Robacker & Hawks, 2022 / HOLOTYPE” . Paratype (1 ♂) labeled: a) as holotype; b) “Sin 9”. Paratypes (2 ♂, 1 ♀) labeled: a) “México: Sinaloa / El Palmito logging road / elev. 6690′ / 14–22 July, 2007 / D. C. Robacker ” ; b) males “Sin 8” or “Sin 10”. Paratypes (3 ♂, 3 ♀) labeled: a) handwritten “ Mex: Sinaloa / Loberas / VI 1983 ” ; b) males “Sin 1” or “Sin 2” or “Sin 6”, females “Sin 12” or “Sin 15” or “Sin 17”. Paratype (1 ♂) labeled: a) handwritten “Loberas / 12 July 86 / #1” ; b) “Sin 4”. Paratype (1 ♀) labeled: a) as previous except “6. July 86 / #2”; b) “Sin 13”. Paratype (1 ♀) labeled: a) as previous except “#3”; b) “Sin 14”. Paratype (1 ♂) labeled: a) handwritten “Mex. Sinaloa / Mpio. Concordia / Loberas , 1975 m / 12 July 86 / E. Welling ” ; b) “Sin 3”. Paratype (1 ♂) labeled: a) handwritten “México: Sinaloa / Loberas / July 1994 ” ; b) “Sin 11”. Paratypes (1 ♂, 1 ♀) labeled: a) handwritten “México, Sinaloa / Loberas / Aug 3 1983 / E. Giesbert, Coll.” ; b) handwritten “ Plusiotis / adelaida / det. E. Giesbert ” ; c) male “Sin 5”, female “Sin 16”. Paratypes (1 ♂, 1 ♀) labeled: a) “México: Chihuahua / Tomachic / elev. 2000 m / 11 August, 2004 / D. Robacker ” ; b) male “Chi 1”, female “Chi 12”. Paratype (1 ♀) labeled: a) “México: Chihuahua. / Basaseachic / dead on ground / 23. viii. 2001 A. K. Owen ” ; b) “Chi 11”. Paratype (1 ♂) labeled: a) “ 6 miles N. E. / El Salto, Dgo. Dist / Dgo. Mex. 8500 ft. / Aug. 10, 1947 ” ; b) handwritten “ AMNH ”; c) “ D. Rockefeller / Exp. Gertsch” ; d) handwritten “ Plusiotis / adelaida Hope / M. A. Morón, det. 1985”; e) “Dur 1”. Paratypes (2 ♂, 2 ♀) labeled: a) handwritten “ Mex: Durango / Buenos Aires / July 1994 ” ; b) males “Dur 2” or “Dur 3”. All paratypes (14 ♂, 11 ♀) labeled on yellow paper, “ Chrysina occidentalis ♂ or ♀ / Robacker and Hawks , 2022 / PARATYPE” .

Description, holotype male ( Fig. 4–5 ). Length 27.2 mm, maximum width 13.4 mm, maximum dorso-ventro thickness 9.1 mm. Frons mottled light and dark green; clypeus dark green with lighter green toward margins, clypeus margins green and black; pronotum mottled light and dark green with central reddish brown shallow longitudinal depression, margins golden green. Scutellum green. Elytral inner margin black; elytra with 8 striae containing punctures and 9 interstriae with shallow punctures visible under magnification; elytral structure and color, from inner elytral margin outward, 1 st interstria narrow and dull brown-green except marginal area cream colored, shallow cream stria, 2 nd interstria narrow and brown-green becoming reddish brown at posterior end, deep black and cream stria, 3 rd interstria wide and brown-green becoming reddish brown at posterior end, deep black and cream stria, 4 th interstria narrow and cream, deep black and cream stria fusing anteriorly with previous stria, 5 th interstria narrow and brown-green becoming reddish brown posterior 1/3 of length, shallow cream stria, 6 th interstria narrow and bright green, shallow cream stria, 7 th interstria narrow and bright green, deep golden-cream stria (appears black from above) inside meso-anterior depression, 8 th interstria wide and bright green, shallow cream stria, 9 th interstria wide and bright green becoming reddish brown at posterior end; epipleuron green, outer elytral margin golden posterior to epipleuron; calli not apparent. Last abdominal tergite, visible beyond the terminus of the elytra, golden. Pygidium cupreous with green and gold reflections laterally. Ocular canthi green; antennal scape light brown, remainder of antenna darker brown. Ventral thoracic surfaces mainly brown, prosternal plate light green, mesosternal process gold, medial areas of metasternum green. Abdominal sternites mostly reddish brown with green posterior edging. All femora with outer (ventral) surfaces green with a reddish brown streak extending along the anterior edge and another extending laterally in the disc; inner surfaces of profemora like the outer surface, inner surfaces of the meso- and metafemora mainly brown; posterior surfaces of all femora golden. Tibia colored about the same as femora. Tarsi metallic bronze with greenish reflections. Mentum, mandibles and labrum light green; mandibles with black anterior edging; stipes bronze and green.

Head. Form trapezoidal, about as wide as long. Frons with sparse fine punctures, becoming rugopunctate in an anterior semicircular depression and on the clypeus. Clypeus slightly convex, anteriorly reflexed, semitrapezoidal in dorsal view, slightly notched in center of anterior margin.

Anterior border of labrum emarginated and deeply notched at center. Mandibles symmetrical, anterior and medial edges straight and meeting at right angle, visible in dorsal view. Mentum nearly quadrate but rounded laterally, with a depression in the anterior half; surface rugose with lateral setae, anterior margin widely sinuate. Eye size large with ratio of width of pronotum at base to interocular distance 2.6. Ratio of interocular distance to antennal club length 1.4.

Thorax. Pronotum with a slight central anteroposterior depression in the anterior half, basal margin entire; punctures sparse and very fine (only visible under magnification). Mesosternal process rounded at apex and extending beyond mesofemoral base. Prosternal plate narrow and subtriangular, pointed anteriorly and rounded posteriorly. Epipleural fold terminating near metacoxae. Protibia tridentate. Venter mostly setigerously punctate, less on medial area of metasternum, femora and tibia.

Abdomen. Sternites with sparse setose punctures medially, becoming more abundant laterally; last abdominal tergite abundantly punctate with fine terminal setae. Pygidium surface rugose leathered proximally, rugose punctate distally with setae at margin. Genitalia: Genital capsule length 9.3 mm (linear measurement) or 10.3 mm (basal piece of capsule + phallobase + parameres). Parameres fused, almost symmetrical, but the right paramere (viewed dorsally) bulges laterally slightly at the tip of the ventral plates and bends downward slightly more than the left paramere. Parameres length 4.0 mm; maximum width 2.7 mm in dorsal view, parameres length/ parameres maximum width ratio 1.5, parameres narrowing slightly during the first two thirds of their length then more abruptly during the final third to 0.37 mm at apices; slightly notched at apices; downward curvature of parameres from base to apex 40°. Ventral plates fused at their bases, splitting into two wide structures that narrow medially into pointed projections during the terminal quarter of their length.

Male variation. Color variation mostly in the amount of reddish-brown suffusion, especially on the elytra and femora; replacement of green with beige on the sternites; the amount of black in the deep striae; and replacement of gold with bronze or green on various structures such as the mesosternal process and the edges of the tibia. Variation in degree of punctation on the venter, the interstriae, and the pygidium, the pygidium sometimes completely rugose punctate; abundance of setae varying in proportion with punctation. Some specimens with protibia appearing bidentate.

Means of adult male measurements are shown in Table 1 . Ranges in measurements of males (n = 12): length 24.9–28.5 mm, maximum width 12.0– 13.5 mm, length/maximum width ratio 2.0–2.2, pronotum width 9.4–10.9 mm, interocular distance 3.7–4.2 mm, pronotum width/interocular distance ratio 2.4–2.8, antennal club length 2.6–3.0 mm, and interocular distance/antennal club length ratio 1.3–1.5.

Means of genital capsule measurements are shown in Table 4 . Ranges in measurements of capsules: capsule length 9.5–10.9 mm (n = 10), parameres length 3.6–4.4 mm (10), parameres maximum width 2.6–2.9 mm (10), parameres length/parameres maximum width ratio 1.3–1.6 (10), parameres width at ventral plates apices 1.5–2.1 mm (10), parameres width at apices 0.37–0.46 mm (7), and parameres curvature 38.5–59.5° (10).

Female morphology and variation. Females similar to males in coloration and morphology. Females generally longer and wider than males but with smaller antennal club length.

Means of adult female measurements are shown in Table 2 . Ranges in measurements of females (n = 8): length 26.6–31.3 mm, maximum width 13.1–15.2 mm, length/maximum width ratio 2.0–2.1, pronotum width 9.3–11.9 mm, interocular distance 3.8–4.6 mm, pronotum width/interocular distance ratio 2.4–2.6, antennal club length 2.3–2.7 mm, and interocular distance/antennal club length ratio 1.6–1.8.

Inferior genital plates are teardrop shaped with narrowed apices projecting laterally to a point. No consistent differences with C. adelaida were observed among the eight females of each species examined ( Fig. 16–17 ).

Diagnosis. Chrysina occidentalis is distinguished from both red and green forms of C. adelaida by its narrower body shape (length/width range 1.98–2.19 vs 1.89–2.09 for C. adelaida ), generally green color with red on the posterior of the elytra and small longitudinal red stripe on the pronotum ( Fig. 4 vs Fig. 2, 6, 8 for C. adelaida ), reddish pygidium and reddish brown sternites in combination with overall green coloration of the elytra ( Fig. 4–5 vs Fig. 2–3, 6–9 for C. adelaida ), green on the femora of most specimens in combination with reddish brown sternites ( Fig. 5 vs Fig. 3, 7, 9 for C. adelaida ), narrower parameres especially at the apices ( Fig. 10–11 vs Fig. 12–13 for C. adelaida ; parameres width at apices range 0.37–0.46 mm vs 0.44–0.73 mm for C. adelaida ), and parameres more strongly curved ventrally ( Fig. 14 vs Fig. 15 for C. adelaida ; curvature angle range 38.5–59.5° vs 24.0–37.0° for C. adelaida ).

Distribution of C. occidentalis . Populations we studied from the Sierra Madre Occidental in the states of Chihuahua, Sinaloa, and Durango represent C. occidentalis . Populations from Jalisco and Michoacán, located in the Trans Volcanic Belt, match neither C. occidentalis nor C. adelaida . Pending further study, we refer to these as C. adelaida (of authors). These populations likely are isolated from C. occidentalis by lowland tropical forest or xeric shrublands ( Fig. 1 ). We know of no specimens of C. occidentalis or C. adelaida (of authors) from Sonora, eastern Chihuahua, eastern Durango, western Coahuila, Zacatecas, Aguascalientes, or Guanajuato. Chrysina occidentalis would be expected in Sonora, western Zacatecas, northern Jalisco, and eastern Nayarit where oak-pine forests occur. McCormack et al. (2008) stated that populations of Mexican jays in the Transvolcanic Belt are geographically isolated from populations to the north by the Aguascalientes Graben and the Bajío Depression. Also, the Chihuahuan desert covers much of Chihuahua and Coahuila, and some of eastern Durango. As such, populations of neither C. occidentalis nor C. adelaida (of authors) would be expected in eastern Chihuahua, western Coahuila, eastern Durango, eastern Zacatecas, Aguascalientes, or Guanajuato.

Etymology. This new species is named for its home in the Sierra Madre Occidental in western Mexico.

Figures

Figure 1.Locations in Mexico of montane oak-pine forests (modified from Guzmán 2008) and of Chrysina populations studied in this work. Mountain ranges: SMOc Sierra Madre Occidental, TVB Trans Volcanic Belt, SMOr Sierra Madre Oriental, SMS Sierra Madre del Sur. States discussed in the text: A Aguascalientes, C Chihuahua, Co Coahuila, D Durango, G Guanajuato, Gu Guerrero, H Hidalgo, J Jalisco, Mx Estado de Mexico, Mi Michoacán, M Morelos, N Nayarit, NL Nuevo León, O Oaxaca, P Puebla, Q Queretaro, Si Sinaloa, So Sonora, T Tlaxcala, V Veracruz, Z Zacatecas.

Figures 2–9. Dorsal and ventral habitus of adult Chrysina specimens. 2–3) P. adelaida holotype female (courtesy of Oxford University Museum of Natural History). 4–5) C. occidentalis holotype. 6–7) C. adelaida red-form from Veracruz, Mexico. 8–9) C. adelaida green-form from Veracruz, Mexico.

Figures 10–17. Chrysina spp. genital structures. 10–15) Male genital capsule dorsal (d), ventral (v) and lateral (l) habitus. 10–11) C. occidentalis holotype. 10) (d). 11) (v). 12–13) C. adelaida from Veracruz, Mexico. 12) (d). 13) (v). 14) C. occidentalis holotype (l). 15) C. adelaida from Veracruz, Mexico (l). 16–17) Female genital plates. 16) C. occidentalis from Sinaloa, Mexico. 17) C. adelaida from Veracruz, Mexico.