Triarius texanus Clark and Anderson, 2019

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 : 354-356

Triarius texanus Clark and Anderson , new species

Zoobank.org/ urn:lsid:zoobank.org:act:9BA0DB32-FE22-4B21-B8E7-11E1518BE6CD Figs. 2h , 3f

Diagnosis. The tarsal claws of this species are appendiculate, and the head and metasternum are yellow. The elytra are yellow, except for a narrow, dark brown sutural stripe ( Fig. 2h ). This combination of characters distinguishes this species from all others of the genus Triarius .

Description of Holotype. Form elongate ( Fig. 2h ); body 4.5 mm long, 2.1 mm wide. Head orangeyellow; prothorax yellowish, off-white; elytra pale yellowish, off-white, with black suture; ventral areas largely orange-yellow; antennae and legs bicolored.

Head with 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 minutely punctate and wrinkled, with short mesal impression; long seta present near upper inner margin of each eye; each frontal tubercle glabrous, impunctate, subrectangular, wider than long, contiguous mesad of other tubercle, delimited laterad by shallow, broad impression, abruptly delimited posteriad; mesal frontal ridge subtriangular, minutely punctate, weakly elevated, not carinate; distal portion of clypeus very thin, transparent, covering posterior portion of labrum; genae extremely short, length only slightly greater than diameter of ommatidium. Eyes oval, 0.6 times as long as wide, finely faceted, black, separated from antennal fossae by distance subequal to width of antennomere 2. Labrum testaceous, subrectangular, convex in front, width twice as great as mesal length and slightly less than distance between lateral margins of antennal fossae, with transverse row of long setae; mandibles testaceous with distal portion piceous; maxillary and labial palpi orangeyellow, setose, acutely pointed towards apex.

Antennae nearly filiform, extending to distal elytral declivity. Basal 2 antennomeres testaceous; antennomere 3 pale brown; distal 8 antennomeres dark brown, nearly black, covered with dense pubescence; antennomere 1 slightly curved, shiny, sparsely setose, much longer than broad, much broader distad than basad, about as long as antennomeres 2 and 3 combined; antennomere 2 about half as wide and 1/3 as long as antennomere 1, setose; antennomere 3 slightly longer than 2, much broader apicad than basad; antennomere 4 nearly as long as antennomere 1, distinctly broader distad than basad; antennomere 5 subequal in length with antennomere 4, distinctly broader distad than basad; antennomeres 6–10 subequal in length with 5 and with each other, slightly wider distad than basad; antennomere 11 subequal in width and 1.3 times as long as antennomere 10, narrowed distad to acute point.

Pronotum widest near apical fourth, at greatest width about as wide as head, posterior portion about as wide as interocular space; shape transversely arched; surface glabrous, minutely punctate, shiny; poorly developed tubercle present at anterior and posterior corners, each with 1 long seta; lateral margins strongly carinate, equipped with sparse row of short setae; posterior margin with complete, glabrous carina lined posteriorlly by short, closely spaced setae; anterior margin without carina, lined with row of very short, closely spaced setae. Scutellum amber-colored, equilaterally triangular, glabrous, impunctate, shiny.

Elytra 3.5 mm long, together slightly wider than head, distinctly wider than base of pronotum, 3.5 times as long as pronotum, 0.7 times as long as entire body. Humeri well-developed; basal calli poorly developed, without distinct impression behind. Discal surface minutely punctate; interpunctural areas slightly alutaceous, shiny; pubescence largely absent, but sparse, short setae present on distal declivity and along epipleura.

Body beneath orange-yellow, except metepisterna darker. Ventral areas of prothorax glabrous, shiny; anterior margin lined with fringe of setae that are long in mesal area and shorter in lateral areas; posterior margin lined by fringe of short, closely spaced setae; prosternum anterior to coxae short, length subequal to maximum diameter of antennomere 1; posterior prosternal process very narrowly separating coxae; procoxal cavities narrowly open behind. Mesothorax shiny, nearly glabrous. Metathorax densely pubescent. Abdomen sparsely pubescent; terminal ventrite with large rectangular lobe flanked by deep notches.

Coxae and trochanters pale yellow-brown. Femora pale yellow-brown, sparsely pubescent. Tibiae dark brown, nearly black, densely pubescent, each with terminal spur. Tarsi dark brown, nearly black, densely pubescent; basal tarsomere of front legs distinctly widened, about as wide as tibial apex; basal tarsomeres of middle and hind legs narrow; tarsomere 1 of hind legs nearly as long as tarsomeres 3–5 combined; claws appendiculate, outer lobe very narrow and pointed at apex, inner lobe broad, comparatively blunt.

Aedeagus symmetrical in dorsal view, evenly curved in lateral view ( Fig. 3f ).

Variation. Males measure 4.4–5.3 mm in length; females measure 3.2–5.8 mm in length. In some specimens, the sutural vitta of the elytron is slightly broader than in others.

Holotype. “ TEXAS: Brewster Co. / BBNP, Lost Mine Trail / (upper ridge), 6,800 ft. / 29°16’09”N, 103°16’04”W / X-3-2005, Raber & Riley-66 // beating / Juniperus / flaccida Schlecht. ” (male, TAMU).

Paratypes. TEXAS: Brewster Co.: [same data as holotype] (4 males, 4 females, BYU; 32 males, 57 females, TAMU) ; [same date as holotype, except without plant-association label] (3 males, 2 females, TAMU) ; Big Bend , X-1957 (1 male, 1 female, TAMU) ; Big Bend Natl Pk, Green Gulch , 11-X- 1966 (9 males, 2 females, USNM) ; Chisos M., 19- IX-1938, D. J. & J. N. Knull (1 male, OSUC); BBNP, Lost Mine Trail (lower), 29°16 ′ 12"N, 103°16 ′ 45"W, 5,760-6,000 ft., 3-X-2005, Raber & Riley (2 females, TAMU); BBNP, Lost Mine Trail (upper), 29°16 ′ 17"N, 103°16 ′ 19"W, 6,000-6,800 ft., 3-X-2005, Raber & Riley (1 female, TAMU); BBNP, Lost Mine Trail (upper), 29°16 ′ 17"N, 103°16 ′ 19"W, 6,000-6,800 ft., 3-X-2005, Raber & Riley, beating Juniperus flaccida Schlecht. [ Cupressaceae ] (1 male, TAMU); BBNP, Pine Canyon Camp, Area no. 4, 29°15 ′ 59"N, 103°14 ′ 04"W, 4,700 ft., 1-X-2005, Raber & Riley, UV light (2 males, TAMU); BBNP, Pine Canyon trail (lower), 29°16 ′ 09"N, 103°14 ′ 01"W, 4,700- 5,000 ft., 2-X-2005, Raber & Riley (1 female, TAMU) . Jeff Davis Co.: Davis Mts. St. Pk., 5-X- 1982, E. G. Riley (3 females, EGRC) .

Plant Association. As noted above, specimens have been collected by beating J. flaccida . However, this may not be a food plant. In a personal communication from Edward G. Riley, who was one of the collectors of the very large series from the upper ridge of Lost Mine Trail, he wrote the following regarding these specimens:

“My colleague Brian Raber and I collected this species in large numbers from a single modest-sized Juniperus flaccida tree growing on the upper ridge near Lost Mine Peak, shortly before the terminus of the Lost Mine Trail. These beetles were nearly absent from adjacent trees of various species including another J. flaccida growing less than 15m away and Pinyon pine and another Juniperus species found in the immediate area. This particular tree, although located on a ridge top, was not particularly well positioned to receive a precipitation of wind-blown beetles from below, the phenomenon known to beetle collectors as a ‘blow up.’ Other J. flaccida trees were beaten during this day-long hike, none of which produced Triarius specimens. Mating pairs were not observed. My impression was that these beetles, for some unknown reason, were obviously congregating on this particular tree. Although a field-feeding test was not performed, I did not feel these beetles were feeding on the Juniperus . One explanation for the congregation could be that the beetles were preparing to spend the coming winter months among the evergreen Juniperus foliage. However, at present, there are no spring collections recorded for this beetle, and, even if there were, that alone would not explain why they congregated on a single tree.”

Etymology. The species epithet (“ texanus ”) refers to the state of Texas where these beetles were collected. However, it is a bit misleading in that it suggests that the beetles are distributed throughout the state, when they have actually been found in only two of the western counties. However, this epithet was used in a PhD dissertation ( Clark 1987), and it is repeated here to avoid confusion.

Comments. Due to superficial similarity, this species is likely misidentified as T. lividus in some collections.

Figures

Fig. 2. Triarius species, dorsal habitus. A) T. pini, male, B) T. pini, female, C) T. trivittatus, D) T. nigroflavus, male, E) T. nigroflavus, female, F) T. melanolomatus, G) T. lividus, H) T. texanus, I) T. novoleonis.

Fig. 3. Triarius species, aedeagi, dorsal and lateral views. A) T. pini, B) T. nigroflavus, C) T. melanolomatus, D) T. lividus, E) T. trivittatus, F) T. texanus, G) T. novoleonis.