Triariodes segonku Clark and Anderson

Clark, Shawn M. & Anderson, E. Russell, 2019, A Review of Triarius Jacoby, 1887 (Coleoptera: Chrysomelidae: Galerucinae: Luperini), with Descriptions of a New Genus and Four New Species, The Coleopterists Bulletin 73 (2), pp. 343-357: 347-348

publication ID 10.1649/0010-065X-73.2.343

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Triariodes segonku Clark and Anderson

new species

Triariodes segonku Clark and Anderson   , new species Fig. 1b, e, h

Diagnosis. The vittate elytra ( Fig. 1b), in combination with the appendiculate tarsal claws, distinguish this species from others in the similar genus Triarius   . The darkly colored head and femora, in combination with the especially distinctive aedeagus ( Fig. 1, h), easily distinguish this from the other known species of Triariodes   .

Description of Holotype. Form elongate oval ( Fig. 1b); body 6.5 mm long, 2.7 mm wide. Head black; prothorax yellow-orange; scutellum black; elytra yellow with brown vittae; ventral areas largely black; legs bicolored.

Head black, except distal portion of clypeus yellow; interocular distance equal to 2/3 head width across eyes; posterior area of vertex smooth, shiny, nearly impunctate; anterior portion of vertex near frontal tubercles densely punctate and pubescent; each frontal tubercle glabrous, impunctate, subrectangular, transverse, about twice as wide as long, with acute extension at anterior angle mesad of antennal fossa, nearly contiguous with other frontal tubercle at posteromesal angle, delimited laterad by shallow depression, delimited posteriad by abrupt depression; mesal frontal ridge subrhomboidal, nearly flat posteriorly, very narrow and carinate anteriorly, rugulose, densely setose; raised area of clypeus strongly transverse, about as wide as distance between eyes, only about as long as width of antennomere 1, densely pubescent behind, with row of long setae in front; distal portion of clypeus yellow, very thin, covering posterior portion of labrum; area posterior to eye and anterior to prosternum covered with long, dense, white pubescence; genae very short, length subequal to width of basal maxillary palpomere, densely covered with comparatively short, white setae. Labrum black, subtrapezoidal, much broader than long, narrower distad than basad, basal width 3.8 times as great as mesal length and subequal to distance between lateral margins of antennal fossae, with transverse row of 6 long setae. Mandibles yellow-orange, tips piceous; maxillary and labial palpi dark brown with pale brown tip, densely setose, acutely pointed at apex. Eyes oval, 1.9 times as long as broad, finely facetted, separated from antennal fossae by distance subequal to width of antennomere 2.

Antennae nearly filiform, extending to about middle of elytra. Basal 3 antennomeres orangeyellow; distal 8 antennomeres black, covered with dense pubescence, with longer setae near apex of each antennomere; antennomere 1 slightly curved, shiny, sparsely setose, much longer than broad, nearly as long as antennomeres 2 and 3 combined; antennomere 2 about half as wide and half as long as antennomere 1, uniformly setose; antennomere 3 slightly longer than 2, nearly twice as broad apicad as basad; antennomere 4 nearly as long as antennomere 1, distinctly broader distad than basad; antennomere 5 slightly shorter than antennomere 4, distinctly broader distad than basad; antennomeres 6–10 subequal in length to 5 and to each other, only slightly wider distad than basad; antennomere 11 subequal in length and width to antennomere 10, narrowed distad to acute point, distal fourth separated from basal portion by shallow groove lined with relatively long setae, therefore nearly appearing to be distinct antennomere, although not freely articulated.

Pronotum widest near apical third, greatest width about 1.3 times as great as that of head, posterior portion about as wide as head; shape transversely arched, shallowly depressed at meson; surface glabrous, minutely punctate, shiny; setose tubercle present at each anterior and posterior corner; lateral margins strongly carinate, equipped with several short setae; anterior margin lacking carina, with dense row of short setae; posterior margin with narrow carina, lined with dense row of short setae. Scutellum black, equilaterally triangular, glabrous, impunctate, shiny.

Elytra 5.0 mm long, together about 1.5 times as wide as head, distinctly wider than pronotum, 5 times as long as pronotum, 0.8 times as long as entire body. Humeri well-developed; basal calli weakly developed, not delimited behind by depression; distinct discal and sublateral costae absent, but 2 shallow depressions present on each elytron, one beginning mesad to humerus, extending backwards to near basal third of elytron, other beginning behind humerus and extending nearly to middle of elytron; epipleura broad in basal half, extremely narrow in distal half. Discal surface minutely punctate; interpunctural areas shiny; pubescence largely absent, but scattered setae present near apex. Color of each elytron yellow with 5 brown, longitudinal stripes; stripe 1 adjacent to suture; next 3 stripes on disc, not united at apex or base, ending near middle of apical declivity; stripe 2 beginning near basal fourth of elytron; stripe 3 beginning mesad of humerus; stripe 4 beginning shortly behind humerus; stripe 5 lateral, occupying epipleuron and adjacent area.

Body beneath black, except prothorax yellow. Ventral areas of prothorax glabrous, shiny; anterior margin lined with fringe of long setae; posterior margin lined with fringe of comparatively short setae; prosternum anterior to coxae short, length subequal to maximum diameter of antennomere 1; posterior prosternal process very narrowly separating coxae; procoxal cavities open behind. Mesothorax shiny, glabrous. Metathorax densely covered with white pubescence throughout. Abdomen densely covered with white pubescence laterally, glabrous or sparsely pubescent medially; terminal ventrite mostly black, paler brown apically, with strong mesal impression in distal half and large rectangular lobe at apex; terminal tergite black, slightly visible beyond elytra, densely pubescent and punctate.

Legs largely covered by dense, white pubescence. Coxae dark brown, nearly black. Trochanters brown, distinctly paler than coxae. Femora dark brown, except pale yellow-brown near apex. Tibiae orange-brown, each with terminal spur. Tarsi orange-brown; front and middle legs with basal tarsomere distinctly widened, about as broad as tibial apex; claws appendiculate.

Aedeagus strongly asymmetrical, spatulate apically, with spatulate portion subrectangular, much longer than broad ( Fig. 1h).

Variation. Males measure 5.4–6.8 mm in length; the single female measures 8.1 mm in length. In the female, the basal tarsomere of the front and middle legs is narrower, the elytral vittae are comparatively weak, and there is no rectangular lobe at the abdominal apex.

Holotype. “ MEXICO: Puebla, / 7 km SSE Acatlan / (Hwy. 190), 1280m / July 5 1992 / Charles Bellamy” (male, BYU).  

Paratypes. MEXICO: Oaxaca: 8 mi. E. Nochixtlan, 28-VI-1971, Ward & Brothers (1 male, EGRC)   . Puebla: [same data as holotype] (2 males, 1 female, BYU; 1 male, UNAM)   ; 6 mi. sw. Tehuacan , 8-VII- 1981, Bogar, Schaffner, Friedlander (1 male, TAMU)   ; 1.5 km NW Yucunduchi, Hwy. 90, 17°56.534 ′ N, 97°52.658 ′ W, 19-VII-2003, C. L. Bellamy, CLB851 (3 females, AJGC) GoogleMaps   .

Etymology. “Segonku” is an Indigenous American word meaning skunk. Although the pale areas of the elytra are yellow, rather than white, the vittate pattern is suggestive of a skunk. The epithet is treated as a noun in apposition.

Comments. Although currently known from only Oaxaca and Puebla, this species may occur also in other states in southern Mexico.


Monte L. Bean Life Science Museum


Universidad Nacional Autonoma de Mexico


Texas A&M University