Epicastini, Vitali, Francesco, 2025

= Epicastini Lacordaire, 1872 n. syn.

Epicasta Thomson, 1864 View in CoL

Epicasta malayana n. sp.

( Fig. 1)

ZooBank: https://zoobank.org/ 3B4D97D5-19DC-4C79-A19F-F3BAA38F6CD4

Holotype, ♀, Malaysia, Pahang, Cameron Highlands , IV-2020, local collector, in CFV ( Fig. 1).

Paratype, 1 ♀, Malaysia, Perak, local collector, in CSD .

Other examined material

- Epicasta ocellata Thomson, 1864 View in CoL , HOLOTYPE, ♂: ocellata / Typ. Thoms[on] / Java [handwritten on a yellow framed label] // Th. [omson] / Type [handwritten and printed on a black framed label] // Musèum [sic!] / Paris [printed on a white label] // HOLOTYPE [printed on a red label], in MNHNP (Fig. 2).

- Psaumis turbidus Pascoe, 1866 View in CoL , HOLOTYPE, ♀: Borneo , Sarawak, in BMNH (Fig. 3).

- Dihammus biocellatus Breuning, 1940 View in CoL , HOLOTYPE, ♂: Sumatra / Corinchi Lake [handwritten a white label] // Dihammus / biocellatus / mihi Typ! / dét. Breuning [handwritten by Breuning and printed on a white label] // sp. n. / biocellatus / Brg. [handwritten by Tippmann on a black framed label] // BLNO / 000344 [printed on a sky-blue label] // HOLOTYPE [printed on a red label], in USNM (Fig. 4).

Description

Body length 24 mm. Habitus elongated.

Coloration. – Integument reddish brown, covered with dense recumbent fulvous pubescence on antennae, legs, ventral side and most of the dorsal side. Pronotum dorsally covered with grey pubescence; at each side, with a pre-apical pitch-brown spot and a longitudinal pitch-brown band that does reach either the pre-apical or the pre-basal furrow. Scutellum covered with golden pubescence. Elytra crossed by a grey pre-median V-shaped band and a grey pre-apicalΛ- shaped band,which are separated along the suture by anelongate pitch-brown spot; apex more or less darkened.

Head. – Frons parallel-sided, elongated, smooth; clypeus very narrow, glabrous; labrum feebly bilobed; eyes about three times as long as genae; vertex smooth. Antennae long, about 1.5 (♀) times as long as body; antennomere VIII (♀) surpasses the elytral apex; scape feebly conical, nearly cylindrical, truncated and with a feebly open cicatrix at apex; pedicel transverse; antennomere III 1.5 times as long as scape.

Pronotum. – Transverse, straight at apex, bisinuate at base, with two transverse furrows at apex and at base; each side armed with a large conical tooth, obtuse at apex; disc uneven, with three weak tubercles on the disc, two anteriorandoneposterior,reaching theapicalandthe basalfurrows respectively; surface between irregularly covered with quite dense fine punctures.

Scutellum . – Rounded, apically triangular and densely pubescent.

Elytra. – Narrow (each elytronhardly4 times aslongas wide atbase), tapered to the apex; apex evenly rounded; disk covered with dense pubescence and an almost regular puncturing vanishing at the apex.

Legs. – Legs and tarsi of usual length, mesotibiae toothed, claws opposite.

Prosternum. – Anteriorly truncated; last visible urosternite triangularly impressed and posteriorly truncate (♀).

Etymology. – The specific epithet malayana refers to its origin (Malaya, historical name of Malaysia).

Differential diagnosis. – This species is closely related to the already described species (Fig. 2-3), differing from both in the scape with cicatrix and the pronotum with two lateral dark bands. Moreover, it differs from E. turbida (Fig. 3) in the unarmed humeri and in the rounded apex of the scutellum (apically truncated in E. turbida ).

On the other side, Epicasta malayana n. sp. looks extremely similar to Acalolepta biocellata (Breuning 1940) . The only structural difference from this species (Fig. 4) is the prosternum anteriorly rounded rather than truncated, while the elytral coloration is a bit different, the post-scutellar spot being strongly reduced to two lateral spots.

Discussion. – The considered species show a set of characters, usually used to define genera and even tribes (Tab. 1).

- Epicasta malayana n. sp. differs from Acalolepta biocellata (Fig. 4) in the truncated prosternum, but several authors

Tab. 1. The considered species set of characters usually used to define genera and even tribes.

3 4b 4a

2. Epicasta ocellata Thomson, 1864 . a. ♂, holotype. b. Original labels (MNHNP).

3. Psaumis turbidus Pascoe, 1866 . ♀, holotype (BMNH).

4. Dihammus biocellatus Breuning, 1940 . a. ♂, holotype. b. Original labels (USNM). © Copyright 2004-2024. Steven W. Lingafelter, Miguel A. Monné, Charyn J. Micheli, and Eugenio H. Nearns.

(LINGAFELTER & HOEBEKE, 2002; YAMASAKO & OBAYASHI, 2009; VITALI, 2013) considered the mesosternal projection as an insufficient discriminatory character, being a simple apomorphy common to many Lamiinae. In all likelihood, it is a specialised character.

- Epicasta malayana n. sp. differs from E. ocellata View in CoL (Fig. 2) in the ridged scape. This character should imply a different tribe ( Epicastini / Desmiphorini ) but it was proved insufficient to separate Rhodopinina from Lamiini ( Souza et al., 2020) . The polarity (primitive / specialised) of this cicatrix is problematic in the phylogeny of Cerambycidae View in CoL . Certainly, it was not present in archaic cerambycids (absent in nearly all species) and archaic Lamiinae (Pteropliini) but it appeared several times in Cerambycinae ( Xystrocerini , Cerambycini ) and in apparently unrelated Lamiinae ( Mesosini , Sternotomini , Prosopocerini , Phrissomini, Lamiini , Batocerini ). Other tribes of Lamiinae ( Ancylonotini , Dorcaschematini ), as well as Cerambycinae ( Xystrocerini , Callichromatini ), developed different apical structures on the scape: granules, double cicatrices, spines, etc. On the other side, this cicatrix is variously developed inside Lamiini , sometimes very strong, even spinose, sometimes strongly reduced (scarcely developed?), as in Orsidis Pascoe View in CoL , or even absent, as in Rhodopina View in CoL . Thus, it seems that the cicatrix on the scape is a variable character, alone neither sufficient to define a group nor to define a strong phylogenetic polarity.

- Finally, Epicasta turbida View in CoL (Fig. 3) is the most peculiar species of the group, so much so to be originally considered close to some Onciderini . Actually, species with and without humeral angles/spines are present in several tribes ( Lamiini , Mesosini , Onciderini , etc.) and even inside the same genus, e.g., Agelasta Newman View in CoL ( Mesosini ). The elytra are strongly reminiscent of Zygocerini , but other morphologic characters (shape of head and prothorax, antennal length) do not fit this Australian tribe. However, the angulated humerus is a specialised character in this case as well.

In conclusion, none of the analysed characters is sufficient to discriminate into which tribe this taxon belongs.

The coloration of these species is too particular to not consider them as closely related. Nonetheless, the analysed characters (prosternum, scape, humerus) are typically used to separate different genera or even tribes.

Is it about convergent evolution? It does not seem to be the case since the species inhabit split regions.

According to Tavakilian (2024) “the generic material can be horizontally transferred from an organism to another by the very fact that they share the same food plant.” This can explain why species belonging to different genera and even families share the same coloration. Nonetheless, this intriguing hypothesis was not proved scientifically. Moreover, the species examined here do not share the same habitat, not even the same distribution and, maybe, the same food plant.

The limits of the morphology in the classification of Lamiinae are here very evident.

The presence of the cicatrix on the scape, in addition to the aspect and the furrowed mesotibiae, makes E. malayana n. sp. a clear member of Lamiini .

On the other side, Epicasta has really little to do with the American genus Desmiphora Audinet-Serville, 1835 . Its classification in this tribe is only due to the smooth scape, but this character was proved insufficient to separate other “ Desmiphorini ” from Lamiini ( Souza et al., 2020) .

If E. malayana n. sp., as it seems, it closely related to the already described Epicasta , its continental distribution suggests that the cicatrix on the scape is, in this case, a primitive character that disappeared in the insular species ( E. ocellata and E. turbida ). Analogously, the angulated humerus is a specialised character which evolved in an insular species ( E. turbida ). This seems to constitute a gradation of characters inside of the same genus, which emerged in continental Malaysia and evolved in the adjacent islands.

Consequently, the tribe Epicastini is removed from the synonym with Desmiphorini and considered as a new synonym of Lamiini .

The position of Acalolepta biocellata remains questionable. Moreover, the characters of Epicasta malayana n. sp. (opposite claws, toothed mesotibiae, scape with open cicatrix, parallel-sided frons, truncated prosternum, elytra rounded at apex and punctured at base) correspond to the genus Pseudodihammus Breuning, 1936 as well. Currently this genus includes two species, possibly synonyms, widespread in Peninsular Malaysia and Borneo and both characterised by a spotted black-white pubescence (Vitali, 2024).

If the peculiar coloration has allowed merging together the mentioned Epicasta species ignoring some structural characters, then Acalolepta biocellata should be also merged into Epicasta . By the way, it is the only Acalolepta showing this peculiar coloration. Nonetheless, the structural characters of the genus Epicasta would become quite disparate (prosternum rounded or truncated, scape ridged or simple, humerus rounded or angulated) and the genus would be only characterised inside Lamiini by its dorsal coloration.

Otherwise, if the structural characters are taken into account, Pseudodihammus should be merged into Epicasta , despite its different coloration. Actually, the particular coloration of E. malayana , E. ocellata and E. turbida could be another specialised character, while Pseudodihammus shows a simpler, likely more primitive, coloration. This might be confirmed by the fact that both Pseudodihammus species show a more developed cicatrix on the scape.

Nonetheless, the fact that Pseudodihammus is an insular genus goes against the hypothesis that specialised characters evolved in insular species, as previously supposed. Actually, the Sunda Shelf, which connected together Malacca, Borneo, Sumatra and Java during the Glacial ages ( Earle, 1845), formed several times and these species (or better, their ancestors) merged together several times as well; hence, these phylogenetic hypotheses are too simplistic.

Considering that the coloration of Acalolepta biocellata is the only character similar to that of Epicasta and that of Pseudodihammus is very different, it is preferred to let the taxonomy stand as it is, and to indicate that this is a provisory and not well-founded solution.

Analysing this group of species, the limits of the morphology in the classification of Lamiinae are very evident. But this problem was already known in the past, as demonstrated by the fact that esteemed specialists grouped species in very different ways according to the characters used in their classification. I did not have the opportunity to examine the male genitalia, since some of these species are known only as females. Possibly, further, e.g., genetic analyses, could give more light on this topic.