Trigonopleurus cordobaalfaroi Otto

Otto, Robert L., 2024, Two new species of false click beetles (Coleoptera: Eucnemidae) from the Americas, Insecta Mundi 2024 (27), pp. 1-9 : 6-8

Trigonopleurus cordobaalfaroi Otto , new species

Fig. 11–17

Diagnosis. Antennal flagellomeres II and III being longer than wide will readily distinguish T. cordobaalfaroi new species from the only other Central American species, T. alienus . The combined lengths of those flagellomeres are about as long as flagellomere I. Trigonopleurus alienus , however, has quadrate flagellomeres II and III, resulting in their combined lengths being shorter than flagellomere I.

Type material. Male holotype: “ USA: LA: W. Feliciana Par.; Feliciana Preserve ; N30.795, W-91.254; 4 June 2014; UV/MV blacklight - MFerro” / “ HOLOTYPE:; Trigonopleurus ; cordobaalfaroi ♂; Otto; det. R.L. Otto; 2022” (red printed label). Female allotype: “ USA: LA: W. Feliciana Par.; Feliciana Preserve; N30.795, W-91.254; 4 June 2014; UV/MV blacklight - MFerro” / “ ALLOTYPE:; Trigonopleurus ; cordobaalfaroi ♀; Otto; Det. R.L. Otto; 2022” (yellow printed label). Holotype and allotype are transferred from CUAC and deposited in CMNH .

Paratypes. 2 ♂♂, 2 ♀♀: GUATEMALA: PETÉN DEPARTMENT : 1 ♂, “ GUATEMALA: Petén; Ixpanpajul, Santa Ana , 180; m, 3-6-2015, J.B.; Heppner & E. Fuller ” / “ PARATYPE:; Trigonopleurus ; cordobaalfaroi ♂; Otto; Det. R.L. Otto; 2023” (yellow printed label) ( FSCA) ; UNITED STATES of AMERICA: LOUISIANA: Feliciana Parish : 1 ♂, 2 ♀♀, “USA: LA: W. Feliciana Par.; Feliciana Preserve; N30.795, W-91.254; 4 June 2014; UV/MV blacklight – MFerro” / “ PARATYPE:; Trigonopleurus ; cordobaalfaroi ♂ (or ♀); Otto; Det. R.L. Otto; 2022” (yellow printed label) (2, CUAC; 1, GERP) . Paratypes are deposited in CUAC, FSCA and GERP .

Description. Male holotype: Length, 6.5 mm. Width, 1.5 mm. Body subcylindrical, elongate; uniformly pitch black; antennae dark reddish-brown; legs including tarsi dark reddish-brown; head, pronotum and elytra clothed with short, recumbent yellowish setae ( Fig. 13 ). Head: Subspherical; integument rugose, dullish; frons convex, without fovea above frontoclypeal region; apical margin of frontoclypeal region weakly trilobed, about 2 times wider than base; mandibles stout, bidentate, densely punctate. Antenna: Filiform to weakly serriform from flagellomeres I–IX, attaining nearly 1/3 the length of the body; flagellomere I longer than II; flagellomeres II–III each sub-equal, longer than wide, each slightly shorter than IV; flagellomeres IV–VIII each sub-equal, longer than wide; flagellomere IX longer than wide, almost twice as long as VIII. Pronotum: Integument dullish, rugose; longer than wide, with moderate, sharp hind angles; parallel-sided, cranially arcuate; lateral pronotal ridge incomplete, cranial 1/2 obliterated; disc convex with deep median groove extending entire length of pronotum and 2 pairs of deep, small, circular fovea; base sinuous. Scutellum: Elongate, sub-triangular, setose, rugose and distally rounded. Elytra: Shallowly to indistinctly striate; interstices elevated; integument somewhat shiny, transversely rugose at basal 3/4, apical 1/4 shallowly punctate. Legs: First tarsomere as long as the combined lengths of the remaining four on mesothoracic and metathoracic tarsi; tibiae rounded in cross section; metathoracic tarsomeres I–III simple; metathoracic tarsomere IV excavate-emarginate; metathoracic tarsomere V somewhat short; pretarsal claws simple. Venter ( Fig. 14 ): Very closely punctate, with short, recumbent yellowish setae; hypomeron with basally obliterated lateral antennal grooves; hypomeron deeply, closely punctate except lateral antennal groove; femoral ridge absent; metepisterna ( Fig. 15 ) slightly wider cranially; elytral epipleura rugose; metathoracic coxal plates medially more than 3.0–6.0 times wider than laterally; last abdominal ventrite apically produced.

Female (allotype) ( Fig. 16 ). Length, 9.0 mm. Width, 2.0 mm. Antennae filiform to weakly serriform, reaching at least 1/3 the length of the body; habitus similar to holotype; legs and antennae dark reddish-brown; flagellomere IX is slightly longer than flagellomere VIII; pronotum similar to holotype; integument similar to holotype.

Aedeagus (paratype) ( Fig. 17 ). Basal piece slightly longer than wide, laterally parallel-sided, dorsally open, apically rounded; remaining parts elongate, constricted laterally just below the base of the parameres, laterally sinuous; parameres elongate, apically pointed, with triangular-shaped lateral tooth present near apices; median lobe elongate and narrow, apically pointed, deeply and narrowly bifid, slightly longer than parameres.

Variation. Two male and 2 female paratypes were examined. The male paratypes measured 4.7–7.0 mm long and 1.0– 1.5 mm wide. The female paratypes measured 8.0 mm long and 2.0 mm wide. Three of the four paratypes are longer than the holotype, but shorter than the female allotype. One of the male paratype is as wide as the holotype, but narrower than the allotype. The two female paratypes are wider than the holotype and just as wide as the female allotype. The male paratype from Guatemala is much shorter and narrower than both the holotype and allotype. The Guatemalan specimen have a much longer lateral pronotal ridge compared to the rest of the specimens in the series, but it remains cranially obliterated. There are no exoskeletal differences between these paratypes compared with the holotype or the allotype.

Distribution. This presumably rarely encountered eucnemid species is known from a single locale in east-central Louisiana and a single location in Guatemala.

Biology. All USA specimens in the series were taken from a combination UV and Mercury vapor light. Immature stages remain unknown.

Etymology. The specific epithet is dedicated in honor of my good friend, confidant and colleague, Jim Córdoba- Alfaro of Puerto Jiménez, Costa Rica; an entomologist, activist and conservationist who has devoted himself to protecting the remaining tracts of the Mesoamerican rainforest and its biodiversity in his country.

Discussion. Placement of T. cordobaalfaroi in the group was based on the comparisons between that species and T. alienus collected from Panama. Specimens of T. rugulosus were not available at the time of study to compare with the two New World species. The relationships for selected members of the tribe, including these three Trigonopleurus species are being evaluated for a potential revision of the tribe at the higher taxonomic level. As more data become available, especially for T. rugulosus , the new species will remain in Trigonopleurus until evaluations are completed.

Otto (2017b) distinguished Trigonopleurus from Miruantennus Otto in the identification key based on the combined lengths of antennomeres IV and V being shorter than III for Trigonopleurus ( Miruantennus has antennomeres IV and V as long as III). The new species does not fit Miruantennus based on observed external morphology. The presence of cranially obliterated lateral pronotal ridge in the new species is more aligned with T. alienus . Based on the preliminary trends in the character matrix, characteristics of flagellomeres II and III may not be a strong state to distinguish Trigonopleurus from any other groups within the tribe. The cranially obliterated lateral pronotal ridge may be a strong enough state to distinguish the group. That character state somehow appears to have escaped the attention of Horn (1890) at the time he described his T. alienus . It is uncertain whether the character state is present in T. rugulosus and needs to be verified as it relates to the two New World species presently assigned in the group. Bonvouloir (1875) did not cover the lateral pronotal ridge in his original description of Trigonopleurus or his species, T. rugulosus (a roughly sculptured, bicolored species from Victoria, NSW Australia). Furthermore, the analysis at the higher level of classification may possibly paint a different picture for the status of these two species as relates to T. rugulosus (which serves as the genotype for Trigonopleurus ) for these two species may belong to a new group.

Trigonopleurus sensu stricto (i.e., T. rugulosus ) is very closely related to Nematodes Berthold and Neomathion Fleutiaux within the tribe. The group differs from both Nematodes and Neomathion based on the presence of caudally widened metathoracic episterna. The metathoracic episterna is parallel-sided in both Nematodes and Neomathion . Muona and Teräväinen (2020) have illustrated the head of T. rugulosus . In comparisons with the image from Muona and Teräväinen (2020) and that of the recently described larva of Nematodes penetrans (LeConte) provided by Otto (2017a), there seem to be some similarities between these two groups, particularly with the structures of the head and mandibles. Larvae of Neomathion still remain unknown. As more data become available for these groups in the future, the analysis will provide us with a better understanding in regards the relationships between these groups within the tribe Nematodini .

Figures

Figures 11–17. Trigonopleurus cordobaalfaroi Otto, sp. nov. 11) Base of hypomeron. 12) Pronotum, lateral view. 13) Male holotype, dorsal view. 14) Male holotype, ventral view. 15) Male holotype, metaepisterna. 16) Female allotype, dorsal view. 17) Aedeagus (paratype), dorsal view. (Scale: 11–12, 15, 17 = 0.5 mm; 13–14, 16 = 1.0 mm.)