Xalitla Lane, 1959

Santos-Silva, Antonio & Frederick W. Skillman, Jr., 2020, Description of a new species of Xalitla Lane, 1959 (Cerambycidae: Cerambycinae: Neoibidionini) from western Mexico, Insecta Mundi 2020 (765), pp. 1-9 : 2-3

Xalitla Lane, 1959

Xalitla Lane 1959: 15 ; Martins 1960: 115; Martins and Chemsak 1966: 457; Martins 1970: 957 (rev.); Monné 1993: 56 (cat.); 2005: 389 (cat.); 2012: 38; 2019: 559 (cat.).

Lane (1959) described Xalitla in Ibidionini Thomson, 1861 with Xalitla azteca Lane the type species (currently, Neoibidionini Monné, 2012 as Ibidionini Thomson, 1861 was found to be preoccupied). Martins (1960) included Xalitla in his key to genera of Ibidionini and reported (translated and paraphrased): “ Xalitla and Gourbeyrella have a strong constriction at the base of the prothorax, with Xalitla characterized by the strong punctation of the prothorax and elytra, and with Gourbeyella having the pronotum pleated. The inclusion of either in Ibidionini [being proper] seems to us very doubtful.” These comments aside, Martins (1967) transferred Gourbeyrella to Tillomorphini but left Xalitla in Ibidionini . Martins (1970) kept Xalitla in Ibidionini , Division V (currently Compsina Martins and Galileo, 2007 ), and described two new species: X. genuina , and X. punctatissima . Later, Galileo and Martins (2008) described X. lezamai . The presence of Xalitla in Neoibidionini is questionable as no other genus in the tribe has coarsely reticulate-punctate pronotum.

This is also problematic as Lacordaire (1868) separated Ibidionini (= Neoibidionini ) from Tillomorphini by the size of the ommatidia: coarse in Neoibidionini ; fine in Tillomorphini . However, this feature is variable in the genera currently placed in Tillomorphini (as well as in genera of other tribes of Cerambycidae ). Accordingly, it cannot be used to separate tribes.

Although the status of the current tribes of Cerambycinae is not the scope of this work, some considerations are necessary to justify the inclusion of Xalitla in Neoibidionini , as Xalitla can be included in more than one tribe, depending on the features and species chosen.

Neocorini Martins, 2005 was described as follows (translated): “Eyes coarsely faceted; upper eye lobes narrow or absent. Maxillary palpomere I distinctly longer than the others. Scape as long as, or longer than, antennomere III. Antennomere not carinate, not sulcate, often shorter or subequal to IV. Antennomere V distinctly longer than IV. Prothorax longer than wide, rounded and without tubercles laterally, with distinct basal constriction. Procoxal cavities closed behind, not forming lateral angle. Pronotum without tubercles. Mesoventral process emarginated posteriorly, often without articular lateral projection. Mesepimeron very narrow. Mesocoxal cavities closed laterally. Elytra not carinate, often with transverse depression about middle; elytral apex without projections. Meso- and metafemora pedunculate-clavate. Metatibiae not carinate. Parameres individualized.” Almost none of these features can really be used to define the genera currently included in the tribe. For example, Neocoridolon Melzer, 1930 , has antennomere III longer than IV, and outer angle of elytral apex distinctly spiniform; Fregolia Gounelle, 1911 has distinct tubercles on pronotum, and elytra also distinctly carinate. Furthermore, it was affirmed that maxillary palpomere I is longer than the other maxillary palpomere segments. However, the drawing of Neocorus ibidionoides (Audinet-Serville, 1834) , as well as other information in the same work provides very different information (translation): “Maxillary palpi in Neocorus with palpomere I very narrow and the shortest.” At the same time, these features are present in Tillomorphini making it impossible, on this basis, to separate Neocorini from Tillomorphini Lacordaire, 1868 . According to Martins (2005) (translated): “Some genera of Neocorini were placed in Tillomorphini by Monné (1993). Neocorini differs from Tillomorphini especially by the antennal formula [proportion between antennomeres], by eyes and elytra. In Tillomorphini the antennomere III is always longer than IV and is as long as V; the eyes are finely faceted with lower eye lobes at most as long as malar area, and the elytra are flattened dorsally.” However, the proportion between antennomeres is somewhat variable in the genera placed in Neocorini , and may be identical to that in Tetranodus Linell, 1896 (which is assigned to Tillomorphini ); the eyes in Tetranodus are not finely faceted; the elytra in some genera currently placed in Neocorini (e.g. some species of Aleiphaquilon Martins, 1970 ) are exactly as in several genera of Tillomorphini , the malar area (genae) is identical to that in many Tillomorphini . Accordingly, we cannot see how to separate Neocorini from Tillomorphini . Also, several of the features used to define the tribe are extremely variable in other tribes. For example, eyes finely or coarsely faceted are present in Acanthoderini , and Eburiini . Lacordaire (1868) separated Graciliini from Anaglyptini Lacordaire, 1868 by the size of ommatidia: coarse, leading to Graciliini ; fine, leading to Anaglyptini and Tillomorphini . However, as seen before, this feature is not useful to separate tribes of Cerambycidae . Lacordaire (1868) also separated Anaglyptini from Tillomorphini by the shape of the mesocoxal cavities: open laterally, leading to Anaglyptini ; and closed laterally, leading to Tillomorphini . Linsley (1962) also used the size of the ommatidia to separate Graciliini , Tillomorphini , and Anaglyptini . However, the features used by him in his key, at best, are useful only to separate North American species, and are not reliable characters to define these tribes, especially since the features used (size of ommatidia and elytral shape) are too variable within the genera included in them.

For us, Xalitla , at least X. azteca Lane, 1959 , and the new species described here, belong to Tillomorphini . Even so, the separation of Tillomorphini from some other tribes (especially Anaglyptini , Graciliini , and Neocorini ), and at least from some genera currently placed in Neoibidionini , remains questionable. Accordingly, provisionally we prefer to keep Xalitla in Neoibidionini .