Oectropsis Blanchard, 1851

Nascimento, Francisco Eriberto De L., Monné, Miguel A. & Santos-Silva, Antonio, 2020, On the enigmatic genus Oectropsis Blanchard (Coleoptera, Cerambycidae Lamiinae): tribal allocation, synonymy, and new species, Zootaxa 4845 (2), pp. 211-224 : 212-213

Oectropsis Blanchard, 1851

Oectropsis Blanchard, 1851: 503 ; Thomson, 1861: 383; 1864: 47; 1865: 365; Lacordaire, 1872: 810; Monné, 2005: 109 (cat.); Barriga & Cepeda, 2005: 44 (rev.); Monné, 2012: 72; Monné, 2020: 155 (cat.); Bezark, 2020a: 222 (checklist).

Pogonocherus ; Fairmaire & Germain, 1859: 514 (syn.).

Type-species. Oectropsis latifrons Blanchard, 1851 (monotypy).

Remarks. Blanchard (1851) described Oectropsis for his new species, O. latifrons , as follows (translated): “Body short and fairly wide. Head short, with wide frons. Mandibles small and acute. Maxillae with its lobes slender, innermost distinctly shorter than outermost, with its palpi cylindrical. Labium narrow basally, widened and rounded apically. Antennae very separated in their insertion, longer than the body, filiform, scape inflated, antennomere IV the longest of all, the others successively decreasing in length, the last thin and pointed. Prothorax short and wide, uneven above, and provided with a small tooth on each side. Elytra very wide, uneven above and rounded at the extremity. Legs rather short, with coxae slightly inflated, tibiae straight.” Although he did not provide details about the elytral surface, he indicated that there are two tubercles, one centrobasal, and beyond the middle. Blanchard (1851) also commented (translated): “This genus is located next to Exocentrus and Pogonocherus ; but the width of the forehead, the brevity of the prothorax, the wider and more depressed shape of the elytra, easily distinguish it from them.” The differences pointed out separating Oectropsis from Exocentrus and Pogonocherus do not allow their separation, especially when considering the type species of each genus. The three features used by him are very variable in the species currently allocated in Exocentrus and Pogonocherus .

In the same work, Blanchard (1851) described Exocentrus pusillus , and stated about Exocentrus Dejean, 1835 (translated): “The type species of this genus is Exocentrus balteatus ( Cerambyx balteatus Lin. ) from Europe.” However, the type species of Exocentrus cannot be Cerambyx balteatus (in fact, Cerambyx balteus Linnaeus, 1767 ) because, in this case, Exocentrus would be equal to Parmena Dejean, 1921 ( C. balteus is currently in this genus, which is the type genus of Parmemini). Gilmour (1965), in his catalog, transferred E. pusillus to Oectropsis , but expressed his doubt using a question mark symbol. However, the two next works mentioning this species still considered it in Exocentrus ( Cerda 1986; Barriga et al. 1993). Finally, from Monné & Giesbert (1994) the species appears included in Oectropsis . It is important to note that Blanchard (1851) considered Oectropsis and Exocentrus as belonging to Acanthocinini and, as he compared the former with Pogonocherus , evidently he also considered this later in Acanthocinini .

Dejean (1835) proposed Exocentrus for many species. According to Bousquet & Bouchard (2013): “Originally included available species: Cerambyx balteus Linnaeus sensu Dejean, 1835 (as “Balteatus. Fabr.”); Cerambyx crinitus Panzer, 1795 ; Cerambyx lusitanus Linnaeus, 1767 (as “ Lusitanicus. Olivier. ”);” and, “The names crinitus and lusitanicus are listed in synonymy with balteatus in Dejean’s catalogue; therefore the type species of Exocentrus is balteus sensu Dejean by monotypy ( ICZN 1999: Article 68.3).” We do not agree with this statement, especially because Cerambyx balteus sensu Dejean is not an available name. The Article 68.3 of the ICZN (1999) does not support this, despite knowing that C. balteus sensu Dejean is C. lusitanus Linnaeus, 1767 . We believe that the designation by Sama (1993) is the correct: Callidium lusitanicum Olivier, 1790 (in fact, Cerambyx lusitanus Linnaeus, 1767 ).

According to Mulsant (1839), who mistakenly attributed the authorship of Exocentrus Dejean, 1835 to himself (translated): “Elytra integer. Prothorax not tuberculate,” leading to Exocentrus ; “Elytra obliquely truncate at apex. Prothorax tuberculate,” leading to Pogonocherus . For Mulsant (1839), Exocentrus and Pogonocherus belonged to Pogonocherini . However, the species currently included in this genus appear to have very variable features.

Fairmaire & Germain (1859) transferred O. latifrons to Pogonocherus , and reported (translated): “It seems to us difficult to separate this genus [ Pogonocherus ] from that Mr. Blanchard created under the name of Aectropsis [sic] (in Gay, Hist. De Chile, Zool., V, 503), and that we would hardly recognize from the plate where it is illustrated.” In fact, the figure provided in the original description is very inaccurate. They did not inform the tribe in which they considered Pogonocherus . Thomson (1861), without any explanation, mentioned Oectropsis as a distinct genus (the tribe was not provided); Thomson (1864) listed Oectropsis in Apomecynini ( Exocentrus and Pogonocherus were included in “Hebestolitae”). Since Thomson (1861) Oectropsis has been considered as a genus distinct from Pogonocherus .

Comparing the species currently included in Oectropsis (at least the type species ( Figs. 1–4 , 18 )) and Pogonocherus , it is difficult to separate them morphologically. According to Linsley and Chemsak (1985), Pogonocherus differs from Lophopogonius Linsley, 1935 , by the absence of a large centrobasal crest. Furthermore, according to them, the pronotum in Pogonocherus has small or obsolete discal tubercles. Examination of the species of Pogonocherus shows that this latter character is inexact. For example, in P. penicillatus LeConte, 1850 (see photographs on Bezark 2020b) the pronotal tubercles are very distinct. Furthermore, when comparing Oectropsis with non-American Pogonocherus ( Figs. 19–26 ), the characterization of the latter by Linsley & Chemsak (1985) is still more questionable. For example, the centrobasal crest is present in Pogonocherus hispidus (Linnaeus, 1758) ( Figs. 19–22 ), the type species of the genus. Also, it is important to note that the other two species of Oectropsis have no evident tubercles on the pronotum, and the centrobasal crest is absent or nearly so ( Barriga & Cepeda 2005).

In his revision of Exocentrus, Breuning (1958) indicated that Exocentrus pusillus did not belong to this genus, but did not include it in any other genus. He considered the genus divided into 10 subgenera, and only mentioned that the pronotum in the genus is transverse, and with a curved lateral spine. Breuning (1975) provided a similar pronotal description for Pogonocherus : pronotum transverse, convex, with a lateral spine. Apparently, the only reliable difference between Pogonocherus and Exocentrus is the presence ( Pogonocherus ) or absence ( Exocentrus ) of the pronotal tubercles.

As species of Pogonocherus (especially non-American species) present variable features (e.g. shape of elytral apex), we are provisionally keeping Oectropsis separate from Pogonocherus because it would be necessary to review the latter, to confirm if all species belong to it. From the American species of Pogonocherus , Oectropsis would differ by the rounded elytral apex, but even this feature is highly variable in the American species. For example, if the current synonymy of P. penicillatus LeConte, 1850 is correct, then the elytral apex is variable including intraspecifically (see photographs on Bezark 2020b). This feature makes the separation between Pogonocherus and Oectropsis weakens.

Oectropsis also resembles Poliaenus Bates, 1880 , but differs by the antennomere III shorter than IV (antennomere IV at most as long as III in Poliaenus ). It differs from Lophopogonius Linsley, 1935 , by the elytra with two crests (only centrobasal crest present in Lophopogonius ), and rounded elytral apex (truncate and with outer angle spiniform in Lophopogonius ).

Although the description of Oectropsis by Barriga & Cepeda (2005) is accurate, it is necessary to change some details in it to allow the inclusion of Oectropsis franciscae (= O. pusillus ): “pronotal disc may have small raised central protuberances”—changed to “pronotal disc with one tubercle on each side of anterior half, from distinctly to slightly elevate”; “elytra may have two small protuberances covered with setae”—changed to “elytra with centrobasal crest, from slight to strongly elevated, with long, erect, abundant setae, and protuberance on center of dorsal surface of the posterior half, with long, erect, abundant setae.” Additionally, it is necessary to add the following: lower eye lobes from slightly shorter to about as long as genal length; upper eye lobes distant from each other; and elytra with long, erect, sparse setae throughout.

Figures

FIGURES 1–4. Oectropsis latifrons, male from Chile: 1) Dorsal habitus; 2) Ventral habitus; 3) Lateral habitus; 4) Head, frontal view.

FIGURES 11–18. 11) Oectropsis chilensis sp. nov., dorsal habitus. 12–13) Oectropsis pusillus, from Barriga & Cepeda (2005) (= Oectropsis chilensis sp. nov.): 12) Dorsal habitus; 11) Lateral habitus. 14) Exocentrus pusillus, “holotype”, dorsal habitus (taken from Tavakilian & Chevillote, 2020). 15–16) Oectropsis franciscae, paratype male, from Barriga & Cepeda (2005): 15) Dorsal habitus; 16) Lateral habitus. 17) E. pusillus, drawing by Blanchard (1851). 18) Oectropsis latifrons, “Lectotype”, dorsal habitus.

FIGURES 19–26. 19–22) Pogonocherus hispidus: 19) Dorsal habitus; 20) Ventral habitus; 21) Lateral habitus; 22) Head, frontal view. 23–24) Pogonocherus fasciculatus (De Geer, 1775): 23) Head, frontal view; 24) Dorsal habitus, specimen 1; 25) Lateral habitus, specimen 1; 26) Ventral habitus, specimen 2.