Ochraethes z-littera ( Chevrolat, 1860 )

Pérez-Flores, Óscar & Toledo-Hernández, Víctor H., 2022, Species delimitation in the genus Ochraethes Chevrolat, 1860 (Coleoptera: Cerambycidae), with description of two new species, European Journal of Taxonomy 845, pp. 1-29 : 23-24

Ochraethes z-littera ( Chevrolat, 1860)

Clytus (Ochroesthes) z-littera Chevrolat, 1860: 476 .

Clytus (Ochroesthes) cristoforii Chevrolat, 1860: 477 , syn. nov.

Ochresthes litura Bates, 1885: 298 .

Ochraestes z-littera – Thomson 1861: 219.

Ochraesthes cristoforii – Thomson 1861: 219.

Ochrestes z-littera – Lacordaire 1869: 66.

Ochrestes cristoforii – Lacordaire 1869: 66.

Ochresthes z-littera – Bates 1880: 51 (distr.); 1885: 297 (distr.).

Ochresthes cristoforii – Bates 1880: 51; 1885: 297 (distr.).

Ochresthes citrinus – Bates 1885: 297 (error).

Ochraethes z-littera – Aurivillius 1912: 386 (cat.). — Blackwelder 1946: 581 (cat.). — Chemsak et al. 1992: 70 (cat.). — Monné 1993: 21 (cat.); 2005: 109 (cat.); 2021: 148 (cat.). — Monné & Giesbert 1994: 116 (cat.). — Noguera & Chemsak 1996: 401 (distr.). — Monné & Hovore 2006; 46 (cat). — Pérez-Flores et al. 2021: 466 (checklist) — Bezark 2021: 74 (checklist).

Ochraethes christofori – Aurivillius 1912: 386 (cat.). — Blackwelder 1946: 581 (cat.). — Chemsak et al. 1992: 69 (cat.).

Ochraethes litura – Aurivillius 1912: 386 (cat.). — Blackwelder 1946: 581 (cat.). — Chemsak et al. 1992: 69 (cat.). — Monné 1993: 18 (cat.); 2005: 107 (cat.); 2021: 145 (cat.). — Monné & Giesbert 1994: 116 (cat.). — Monné & Hovore 2006: 46 (cat.). — Hovore 2006: 373 (distr.). — Pérez-Flores et al. 2021: 466 (checklist). — Bezark 2021: 73 (checklist).

Ochraethes z-litterata – Linsley 1935: 86 (error).

Ochresthes litura – Chemsak 1967: 77 (lect.).

Ochraethes cristoforii – Monné 1993: 18 (cat.); 2005: 107 (cat.); 2021: 145 (cat.). — Monné & Giesbert 1994: 116 (cat.). — Noguera & Chemsak 1996: 401 (distr.). — Monné & Hovore 2006: 46 (cat.). — Pérez-Flores et al. 2021: 466 (checklist). — Bezark 2021: 73 (checklist).

Ochraethes cristofori – Noguera & Chemsak 1996: 401 (cat.).

Chevrolat (1860) described two similar species Ochraethes z-littera and O. cristoforii . According to Chevrolat´s description of O. z-littera : “…sa couleur et les taches du corselet le rapprochent encore du Cl. Cristoforii .” (the colour and pattern approaches that of O. cristoforii ). Although the coloration in these specimens differ, the transverse Z-shaped band of black pubescence on elytra are almost identical. Bates (1885) described O. litura from Guatemala, based on female specimens. In the original description, Bates mentioned that this species resembles O. tomentosus , but larger and with elytral apex “oblique sinuate-truncatis”. Here we propose O. cristoforii and O. litura as junior synonyms of O. z-littera based on the following characters: frons strongly transverse ( Fig. 4M–O ), pronotum with a centrobasal sulcus (pubescence pattern on pronotum is the same in all specimens), patch of yellowish pubescence on first third of elytra, transverse Z-shaped bands of black pubescence on anterior third, and elytral apex with apicolateral spine.

Species delimitation of Ochraethes Chevrolat, 1860

The pubescence pattern on the elytra is the most important character for discriminating the species of Ochraethes ( Linsley 1964) . However, in most species of the genus Ochraethes there is a certain degree of polymorphism, especially in the pubescence (showing tonalities from dark to pale or bright yellow) and integument colour variation ( Fig. 3 ). The delimitation analyses performed in this study allowed the inference of a slight variation in genetic structure within populations of Ochraethes and the high phenotypic plasticity of their species ( Fig. 3 ). However, the specimens with extreme range of variation (dark or bright yellow tonalities) are less common, and this fact may be caused by environmental conditions ( Hartl & Clark 1997; Freeland et al. 2011).

The revised material distribution allowed to explore the influence of other extrinsic factor: exposure to heat or humidity. The specimens that inhabit dry environments showed a light coloration on the body, and the specimens in temperate and cold environments showed a darker coloration. This fact has already been studied in other insect groups (e.g. ants, damselflies), and it is linked to heat regulation mechanisms or different behaviors depending on the temperature ( Bishop et al. 2016; Law et al. 2020; Blow et al. 2021). Also, there may be evolutionary factors related to mimicry strategies, as well as camouflage, i.e., the pubescence matching in colour with the flowers on which the adults feed.

Although populations of species of Ochraethes showed a variable coloration of pubescence and integument, they exhibited diagnostic characters throughout their distribution ( Table 1 ). For most of the species analyzed, we included specimens from different localities, and they were delimited as MOTUs with a high degree of variation. Particularly, O. sommeri shows the largest phenotypic plasticity, and two populations commonly considered as O. sommeri were discriminated as independent lineages (representing the two new species). Moreover, the delimitation analyses support synonymies in some species showing morphological similarities and the same distribution.

On the other hand, sexual dimorphism is common in Ochraethes , for example in O. sommeri , females do not show dark tones in the pubescence. Some other species ( O. nigrescens , O. viridiventris ) show a full range of variation in males and females (even in one locality). This is relevant since several species of Ochraethes described in the past were based on single specimens, or used only one sex, and some of them represent only variations of other species. In the descriptions of new species in this group, the type material should at least include specimens of both sexes for a better taxonomic treatment.

A complete morphological revision of the genus Ochraethes will allow the differentiation and boundaries of the genus from other genera of the tribe Clytini , and subsequent nomenclatural changes and keys for species placed in the related genera.

Figures

Fig. 4.Head, frontal view of type species of Ochraethes. A. Ochraethes brevicornis (Chevrolat, 1860),♀. B. O. virescens (Chevrolat, 1860), ♂. C. O. cinereolus (Bates, 1892) comb. nov., ♀. D. O. octomaculata Chemsak & Noguera, 2001, ♂. E. O. obliquus (Chevrolat, 1860), ♂. F. O. zebratus Bates, 1885, ♀. G. O. sommeri (Chevrolat, 1835), ♂. H. O. circuliferus (Chevrolat, 1860) (= Ochraethes sommeri), ♀. I. Trichoxys giesberti Botero et al., 2019, ♀. J. O. viridiventris (Chevrolat, 1860), ♂. K. O. nigritus Bates, 1892 (= Ochraethes viridiventris), ♂. L. O. clerinus Bates, 1892, ♀. M. O. z-littera (Chevrolat, 1860), ♂. N. O. cristoforii (Chevrolat, 1860), ♂. O. O. litura Bates, 1885, ♀.

Fig. 3. Pubescence variation on the elytra in Ochraethes Chevrolat, 1860. A–B. Ochraethes brevicornis (Chevrolat, 1860) (♀, ♂). C–E. O. cinereolus (Bates, 1892) comb. nov. (♂, ♂, ♀). F–I. O. obliquus (Chevrolat, 1860) (♂, ♂, ♀, ♀). J–N. O. sommeri (Chevrolat, 1835) (♂, ♂, ♂, ♀, ♀). O–S. O. viridiventris (Chevrolat, 1860) (♂, ♀, ♂, ♂, ♀). T–X. O. z-littera (Chevrolat, 1860) (♂, ♂, ♂, ♀, ♀).