G. it. Ent., 15 (65): 843-848
March 2020
Osservazioni integrative sulla femmina di
Cebrio (Tibesia) strictus Gené, 1836
(Coleoptera, Elateridae, Elaterinae, Cebrionini)
di
ROBERTO RATTU & FEDERICO ALAMANNI
Abstract - Additional observations on the female of Cebrio (Tibesia) strictus Gené, 1836 (Coleoptera, Elateridae, Elaterinae, Cebrionini) - The recent finding of 17 female specimens of Cebrio (Tibesia) strictus Gené, 1836, species endemic to southern and western Sardinia (RATTU, 2013), allows new insight into the variability of relevant morphological characters (RATTU, 2016). Wings are illustrated, and information about their variable extension with respect to elytron length is given (wing/elytron length ratio = 0.34-0.44). In addition to the distinctive characters of the subgenus Tibesia [epistoma and labium on different planes, the former slightly protruding above the latter; mandibles scarcely developed, abruptly bent at right angle, apex acute or blunt; outer edge of protibiae sharply denticulate (ZAPATA DE LA VEGA & SÁNCHEZ-RUIZ, 2017)], the additional specimens confirm the peculiarity of the female habitus, characterized by: overall yellowish-testaceous appearance, poorly evident yellowish pubescence, pronotum subrectangular, with shiny appearance due to absent or very scarse punctation on the disc, pubescence on pronotum evidently denser at lateral margins and on posterior angles, which are acute but without spine-like apophysis, elytra subtriangular (dorsal view), short, their apex not or barely exceeding the metacoxae, sharply and abruptly dehiscent, with apex rounded, and striae sharply impressed. Two morphological characteristics mentioned in a previous work (RATTU, 2016) are found to be slightly variable: the character of the lateral outline of eye not protruding with respect to temple is present in all the specimens but one (having barely salient eyes); the anterior margin of the pronotum is notched or sinuated at middle in 14 specimens, whole in 5 specimens. Two other characters, instead, show relevant variability: the length of mandibles, and the shape of the apex of the scutellum, which can be notched, sinuate or whole; according to currently available information, a notch or a sinuation at the apex of scutellum is present in the females of some species from Algeria and Morocco, namely C. (T.) catoxanthus Chevrolat, 1874 (loc. typ.: Bône, currently Annaba), C. (T.). rufangulus Chevrolat, 1874 (loc. typ.: surroundings of Algiers), C. (T.) patruelis Fairmaire, 1866 (loc. typ.: Tangier) (CHEVROLAT, 1874); however, it is not possible to assess the variability of the character in these species.
Concerning the identification of males, owing to their intraspecific variability, morphological characters that are usually suitable for a specific diagnosis may not guarantee a reliable identification (ZAPATA DE LA VEGA & SÁNCHEZ-RUIZ, 2016; RATTU et al., 2018). The only way to differentiate very similar species is thus evaluating the whole set of characters on large series of specimens, and taking into account their provenance, given the restricted ranges typical of Cebrio (s.l.) species.
The identification of females appears thus affected by a similar condition of relevant intraspecific variability, which may reveal critical with single highly anomalous specimens. Examination of the whole set of characters would be thus required, and single problematic specimens should be evaluated within the context of their population, and with the support of geographical information. According to available information, the largest number of females so far known for a species of the subgenus Tibesia concerns C. strictus. Considering the relatively abundant material examined, among the characteristics proposed by ZAPATA DE LA VEGA & SÁNCHEZ-RUIZ (2017) for the identification of females of the subgenus Tibesia - much less numerous than those taken into account for males - we consider the morphology of the epistome the most diagnostic. However, a sound perusal of the already used characters, and the identification of further ones, will be possible only after the description of the several females of Tibesia still unknown.
