Introduction

The prionine genus Trichocnemis has not been formally recognized in North America since it was placed in synonymy with Ergates by Linsley (1962). While the two genera share several characters, and are likely related (Nishio 1956), many characters distinguish the species in these two genera. Earlier authors (Lameere 1901, Casey 1912) considered Trichocnemis a subgenus of Ergates, as was Callergates. More recent authors consider all three as separate genera (Villiers 1978, Jeniš 2001).

Members of all three genera are mainly Holartic in distribution: Ergates occurs in Europe and NW Africa (Jeniš 2008); Callergates occurs in Europe and Asia Minor (Jeniš 2001); and Trichocnemis occurs in western North America (Linsley 1962). Two species of Trichocnemis are recognized: Trichocnemis spiculatus LeConte, 1851 and Trichocnemis pauper Linsley, 1957. The species Trichocnemis spiculatus also has a single subspecies, Trichocnemis spiculatus neomexicanus Casey, 1890. Most species worldwide utilize coniferous hosts, generally in the genus Pinus (Pinaceae) (Linsley op.cit., Villiers 1978); however, Trichocnemis pauper is known only from species in the genus Quercus (Fagaceae) (Tyson 1967). Typically, recently dead host material is preferred by adult females for oviposition, and larval development ranges from two to four years (Linsley op.cit.), depending upon host and environmental conditions.

Males and females are strongly sexually dimorphic, with males having an enlarged, generally smooth prothorax with less distinct lateral spines, while in females the prothorax is smaller and more distinctly spined at the lateral margins. Adults are frequently attracted to ultraviolet lights at night, and are generally active during July and August (Tyson 1967).

Methods

We examined the external morphology of male and female specimens of Trichocnemis spiculatus spiculatus, Trichocnemis spiculatus neomexicanus, Trichocnemis pauper, Ergates faber (Linnaeus, 1761), and Callergates gaillardoti (Chevrolat, 1854), in addition to male genitalia of one species of each genera as well as both species of Trichocnemis, to obtain the conclusions proposed in this study.

Specimens from the following collections were examined for this study:

BMNH The British Museum of Natural History, London, United Kingdom

CASC California Academy of Sciences, San Francisco, California, USA

CSCA California State Collection of Arthropods, Sacramento, California, USA

IRSN Institute Royal des Sciences Naturelles de Belgique, Bruxelles, Belgium

INIA Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria, Spain

EMEC University of California Berkeley, Berkeley, CA USA

USNM United States National Museum, Washington DC, USA

Taxonomic History

LeConte (1851) described the genus Trichocnemis for his new species Trichocnemis spiculatus, stating it was similar to the genus Ergates Audinet-Serville, 1832, but differing in the pubescence of the protibiae. Although LeConte did not indicate the sex of the type specimen, his description suggests it was a female: “Tibiae vix compresse, filiformes”; “thorace scabro, dorso antice bicalloso, spiculis lateralibus valde acutis, apicali basalique majoribus, thorace latioribus”; “the elytra show some indications of costae”; and “the joints of the antennae are marked with a few scattered punctures.” However, the type specimen deposited in the Museum of Comparative Zoology (MCZ) is a male (MCZWeb 2009). There is little doubt that LeConte (op. cit.) based his description on a single specimen, since he indicated only a single measurement, stating: “the specimen appears a little immature.” In males, the tibiae are not clearly filiform, the prothorax is not scabrous and has well-marked depressions (a character omitted by LeConte), the pronotal callosities are less pronounced than in females, the lateral spines of the pronotum are much less prominent than in females, and the proximal antennomeres are strongly and abundantly punctate. In the type specimen (Fig. 1), the elytra show clear carinae, a character that does not agree with the original description.

Although the holotype label of Trichocnemis spiculuatus in the MCZ indicates “Ergates”, and not Trichocnemis, it is believed that LeConte himself changed the label after having transferred the species to the genus Ergates. This is consistent with other LeConte specimens in which the labels indicate different names that the original taxon, for example: Mallodon gnatho LeConte, 1858, which have labels with LeConte’s writing, [Mallodon (Nothopleurus) gnatho // Lec. dentiger Lec.]. Other specimen labels are clearly not written by LeConte (vide Mallodon mandibularis Gemm.).

The genus Ergates was established by Audinet-Serville (1832) to accommodate a single species: Prionus serrarius Panzer, 1793 (= Cerambyx faber Linnaeus, 1761). Among the many characters used to define the genus, Audinet-Serville (op.cit.) listed: legs without internal spines; antennae filiform, similar in both sexes, longer than the body in male, and reaching more or less the middle of elytra in female; antennomere III longer than IV-V together; prothorax finely crenulated laterally in male, more distinctly in female; mandibles and mentum glabrous; legs of medium length, the prolegs longer than the others.

White (1853) synonymyzed Trichocnemis under Macrotoma Audinet-Serville, 1832, but this nomenclatural act was not accepted or used by any later author. White (op.cit.) also did not explain why, in his opinion, that genus was synonymous of Macrotoma.

LeConte (1854) then synonymyzed Trichocnemis with Ergates, stating: “Trichocnemis Lec. (Journ. Acad. 2d, 2, 110) is not sufficiently distinct from Ergates; the Californian species must therefore be called Ergates spiculatus.” Later, LeConte and Horn (1883) pointed out the same observation of Trichocnemis and placed Ergates in the tribe Ergatini. However, the characters used to define Ergatini (sensu LeConte and Horn) apply primarily to Ergates (= Trichocnemis) spiculatus, and largely excludes Ergates faber (Linnaeus, 1761) (Fig. 2) and Callergates gaillardoti (Chevrolat, 1854) (Fig. 3). LeConte and Horn (op.cit.) stated: “the tribe is easily recognized by the prothorax being much broader in the male than in the female, and finely punctured; in the latter sex the sculpturing is very coarse, and the small teeth of the lateral margin are longer and more acute. The head is small, the eyes reniform and coarsely granulated; antennae 11-jointed, slender, two-thirds the length of the body in the ♂, about half the length of the body in the ♀, rough with elevated punctures, with the 3rd joint as long as the three following united; poriferous spaces on the 3rd joint small inconspicuous, on the under surface near the distal end, gradually becoming larger, until the outer joints become entirely poriferous, and irregularly reticulated with fine elevated lines forming elongate cells, which are much less distinct, and in fact hardly to be seen in the male.” This tribal description excludes Ergates faber (Fig. 2) because the head is somewhat large, especially in males; the antennae surpass the elytral apex in males; antennomere III is (at most) as long as IV-V together; the pronotum lacks lateral spines in both sexes, and is not clearly wider in males than in females. Callergates gaillardoti can be unsatisfactorily included, because the antennae is somewhat longer than two-thirds the length of the body in male, the antennomere III is shorter than IV-VI together in both sexes, and the teeth of the lateral margin are not “small” in the female.

Lacordaire (1869) did not revalidate Trichocnemis, although it is clear he did not agree with LeConte’s (1854) synonymy stating: “Le genre Trichocnemis de M. J. L. Le Conte, établi primitivement sur la femelle d’une espèce (3) de Californie, a étè reconnu, plus tard, par se savant entomologiste, comme devant rentrer dans celui-ci. Cette femelle, que j’ai sous les yeux, diffère notablement, sous le rapport du facies, de celle de faber, et a celui d’une Macrotoma; son prothorax est multiépineux sur les côtés et les épines sont longues et irrégulières. D’après la description qu’en donne M. J. L. Le Comte, le mâle différerait également, d’une manière sensible, de celui de l’espèce européenne.”

LeConte (1869) was the first author to attribute subgeneric status to Trichocnemis, when he listed “Ergates (Trichocnemis) spiculatus Lec., ” but did not offer an explanation of this new status. Casey (1890) maintained Trichocnemis as a subgenus of Ergates based on the length of the antennae, anterior legs, and denticulation of the sides of the prothorax, stating: “It seems proper therefore that the name Trichocnemis Lec. should be preserved, if not with full generic value, at least as a subgenus.”

Lameere (1901) considered Trichocnemis different from Ergates (“genre très distinct”), and included both in the tribe “Aegosomites” and subtribe “Callipogonines.” Lameere (1904) assigned Ergates to “Callipogonines, ” and divided it into three subgenera: Ergates (Ergates); Ergates (Trichocnemis); and Ergates (Callergates) Lameere, 1904. Ergates (Callergates) is currently considered a different genus (Jeniš 2001, 2008).

Casey (1912) again considered Ergates and Trichocnemis as distinct taxa, stating: “This genus is distinct from Ergates and should be restored. The last joint of the maxillary palpi in Ergates is oval and more narrowly truncate at apex, while in Trichocnemis it is of a wholly different form, being broadly obtriangular, the sides straight and widely flaring from base to the truncate apex. In the former there is a prominent lateral spiniform tooth at basal third of the prothorax, wanting in the latter, and there are numerous other incongruities. The two genera are related tribally but are unquestionably distinct.” While this diagnosis points out many of the differences between the two genera, several other characters previously mentioned (i.e. antennal length and ratios) were omitted. In addition, Casey (op. cit.) did not indicate a tribal assignment for either of these genera. Nevertheless, taken as a whole, the characters enumerated by Casey (1890, 1912) indicate substantial differences between Ergates and Trichocnemis.

Nishio (1956) pointed out that “the three species of Ergates strongly differ from each other in their morphology” and followed Lameere (1904) in maintaining each species in a different subgenus. Nishio (op. cit.) also compared the male genitalia of the three species, and stated (translated): “The male genitalia of gaillardoti and spiculatus are similar to each other and probably suggest that they are closely related…”. In addition, Nishio (op. cit.) hypothesized the phylogenetic relationship among the three taxa, stating that Callergates gailardoti is the most ancestral species of “Ergates, ” Trichocnemis spiculatus is sister to it, and Ergates faber is the most derived species. Moreover, Nishio (op. cit.) cites Plavilstshikov (1936) as stating that “spiculatus” differs from the remaining species (Ergates faber and Callergates gaillardoti) and should be classified in a different genus.

Linsley (1962) synonymyzed Trichocnemis under Ergates, and assigned it to the tribe Ergatini, stating: “I agree with LeConte and Horn that the characters do not warrant the generic recognition of Trichocnemis and that the phylogenetic unity of the group is better indicated by including all four species in Ergates”. In placing Ergates in the tribe Ergatini, Linsley (op. cit.) apparently ignored the name “Callipogonitae” used by Thomson (1861), and gave “Ergatites, ” used by Fairmaire (1864), priority over the names that appear in Lameere (1904, 1912, 1919): “Callipogonines”; Callipogonini. There seems little doubt that Linsley was aware of the name “Callipogonides” in Lacordaire (1869), and probably incorrectly attributed this taxon to him. This would explain why Lisnley (op.cit.) did not use Thomson’s name for Ergates and Callipogon in the same tribe: “This tribe is represented in America by two genera, Callipogon and Ergates”. Therefore, to Linsley, Callipogonini was equal to Ergatini, and not a different group as considered formerly and by some contemporary authors.

In his work on the Cerambycidae of France, Villiers (1978) considered the three subgenera erected by Lameere (1904) as distinct genera, stating: “Trichocnemis J. LeConte et Callergates Lameere no sont pas des sous-genres d’Ergates, mais des genres bien individualisés”. Villiers (op. cit.), used the tribal name Ergatini, although in a different sense from that employed by Linsley (op. cit.); to him, Callipogonini sensu Lameere included more than one tribe, while Linsley (op. cit.) used Ergatini only as a name with priority over Callipogonini.

The revalidation of Trichocnemis by Villiers (op.cit.) as a separate genus remained unnoticed by many contemporary authors possibly because it was published as a part of a regional faunal account. Nevertheless, subsequent checklists of Western Hemisphere Cerambycidae (Chemsak and Linsley 1982, Monné and Giesbert 1994) unintentionally maintained the synonymy of Trichocnemis with Ergates.

Although the tribal classification of Ergates and Callipogon Audinet-Serville, 1832, is beyond the scope of this paper, it is interesting to note Švácha (1987): “I would like to point out that it is undoubtedly incorrect to classify the genera Ergates and Callipogon in the same tribe, whatever its name may be.” Unfortunately, Švácha did not enumerate the characters he used to base his opinion. Today, researchers of the Neotropical and Nearctic cerambycid fauna use Callipogonini sensu Lameere (1904), while those that work with the fauna of Palearctic, Ethiopian, Oriental, and Australian zoogeographic provinces (with some exceptions), do not agree and use more than one tribe to allocate the genera included by Lameere in Callipogonini.

A partial bibliography of Trichocnemis is listed below, including many citations of the generic name Ergates which actually refer to Trichocnemis (Monné 2006).

Conclusions

Our analysis of these taxa, which corroborates that of Villiers (1978) and in part, those of Lameere (1904) and Nishio (1956), supports recognizing Trichocnemis and Ergates as distinct genera. Additionally, the fact that both species of North American Trichocnemis share several distinct characters not present in Ergates or Callergates further supports this hypothesis.

Summary of taxonomic changes

Trichocnemis spiculatus spiculatus LeConte, 1851 (originally described as Trichocnemis spiculatus LeConte, 1851); Trichocnemis spiculatus neomexicanus (Casey, 1890) (originally described as Ergates (Trichocnemis) neomexicanus Casey, 1890), comb. n.; Trichocnemis pauper (Linsley, 1957) (originally described as Ergates pauper Linsley, 1957), comb. n.

Synonyms of Trichocnemis spiculatus LeConte, 1851

White (1853) described two species from North America (California) that were later synonymyzed with Trichocnemis spiculatus by Lameere (1904): Macrotoma californica and Macrotoma spiculigera. White’s original description leaves some doubt as to the identity of the species involved. For example, in the description of Macrotoma spiculigera, he stated: “Elytra coriaceous, vermiculated, with three indistinct costae”. Similarly, some details of the description of Macrotoma californica might encompass that of Trichocnemis pauper. Since White probably did not examine the types of these species (frequently he indicated when he did), and his original descriptions do not provide enough detail to diagnose them among other Trichocnemis, primarily Trichocnemis pauper, we examined photos of the types, provided by S. Shute (BMNH).

The syntype male of Macrotoma californica (Figs 6, 8) and the holotype female of Macrotoma spiculigera (Fig. 8), are in fact Macrotoma spiculatus, as suspected by even White (op.cit.) himself: “Trichocnemis spiculatus, Leconte, Journ. Acad. Nat. Sc. Phil. n. s. ii 110?”, and “It is possible that this may be the female of the Macrotoma Californica”. Photos of the holotype (Fig. 8) also clearly show three distinct carinae on each elytron, rather than three on the elytra. According to S. Shute (personal communication) the types have the following labels:

Macrotoma californica: Syntype 1 (Fig. 6): White H/W determination label (specimen also bears small circular white H/W  BM(HN) registration label  upper surface reads California, reverse [18] 48 . 135  (the register states that this specimen was purchased from Hartweg);

Syntype 2 (Fig. 7): no labels other than blue BM(NH) syntype label;

Macrotoma spiculigera (Fig. 8): White H/W label. The reverse of this label has Hermerius struck out in black ink and California written below. The generic name is in the large script of White and must have been the original label. This specimen also has a small white circular registration as for Macrotoma calfornica  [18]48 . 135 plus BM(NH) red type label.