Ceroptres petiolicola Osten-Sacken 1865

Ceroptres petiolicola (Osten-Sacken, 1861)

(Figures 4e, 7 g–i)

Amblynotus ? petiolicola Osten-Sacken, 1861. Proc. Ent. Soc. Phila. 1: 67. Type material: MCZ.

Ceroptres petiolicola (Osten-Sacken) Osten-Sacken, 1865. Proc. Ent. Soc. Phila. 4: 369.

Type material (examined). LECTOTYPE (♀) with the following labels: ‘ Ceroptres petiolicola O.S.’ (white label, handwritten) / ‘Osten Sacken Coll.’ (white label) / ‘Type 13975’ (red label) / ‘ MCZ Image Database’ (white label) / ‘MCZ-ENT 00013975’ (white label, QR code) / ‘ Lectotype ♀ Amblynotus? petiolicola Osten-Sacken, 1861, IL-V desig-2018’ (red label) / ‘ Ceroptres petiolicola (Osten-Sacken) Osten-Sacken, 1865, IL-V det. 2018’ (white label).

Diagnosis. Ceroptres petiolicola is morphologically similar to C. catesbaei, from which it can be distinguished by its body coloration (uniformly colored, brownish to black, in C. petiolicola; head and mesosoma black, metasoma brownish orange, in C. catesbaei), the length of the last flagellar segment in females (2.7 times as long as wide in C. petiolicola, 2.3 in C. catesbaei) and the scutellar foveae (separated by a narrow carina in C. petiolicola and by a wide septum in C. catesbaei), among others (see the descriptions of both species and the key to valid species of Ceroptres).

Redescription. Female. Length. Body length 1.8 mm (n=1).

Color (Figs 4e, 7g). Brownish. Head and mesosoma dark brown; tegulae yellow. Antennae yellow, the tip somewhat darker. Legs yellowish with some infuscate areas. Metasoma light brown. Wings hyaline, veins yellow.

Head. In anterior view round-shaped (Fig. 4e), about 1.2 times as wide as high, genae not expanded behind compound eyes. Face with moderately long but not dense pubescence, lower face with short striae radiating from sides of clypeus, not reaching the toruli; medially without striae; vertical carinae incomplete, running from inner ventral margin of the toruli about 2/3 of the lower face length and delimiting a depressed area that is slightly bulged just above the clypeus. Clypeus distinct, basal margin not projected over mandibles. Malar space about 0.5 times as long as height of compound eye. Anterior tentorial pits visible; pleurostomal sulcus absent, epistomal sulcus slightly impressed. Transfacial line about 1.1 times as long as height of compound eyes. Toruli situated slightly below midheight of compound eyes; distance between torulus and compound eye about as long as the diameter of the toruli; distance between the toruli shorter than diameter of the toruli. Front finely coriaceous to alutaceous, with some scarce small piliferous punctures; without frontal carinae. Head in dorsal view is about 2.2 times as wide as long. Vertex finely coriaceous to alutaceous, with some scarce small piliferous punctures. POL:OOL:LOL = 11:5:5 and diameter of lateral ocelli, 3. Occiput finely coriaceous to alutaceous, without punctures.

Antennae. 13-segmented; subclavate, just slightly broadened apically; pubescence dense and short. Scape plus pedicel 1.5 times as long as F1; pedicel just slightly longer than wide; F1 about as long as F2, F2 and F3 subequal, the following segments progressively shorter. Last flagellar segment 2.7 times as long as wide and 2.0 times as long as F10.

Mesosoma. About 1.2 times as long as high in lateral view (Fig. 7g), including nucha, with long, but not dense, pubescence. Ratio of length of pronotum medially/laterally: 0.45. Dorsal part of pronotal plate complete, with two distinct foveae. Lateral pronotum finely coriaceous to alutaceous, without lateral carina. Mesoscutum slightly wider than long, strongly coriaceous. Mesoscutellum (Fig. 7i) about as long as wide, medially strongly coriaceous and wrinkled laterally and posteriorly; circumscutellar carina absent; scutellar foveae ovate, shallow, small, not well defined posteriorly and separated by a narrow carina. Mesopleuron smooth and shiny; little pubescent basally. Metapleural sulcus reaching about 4/5 parts of mesopleural height. Propodeum weakly pubescent and sculptured; propodeal carinae straight and parallel. Nucha weakly sculptured dorsally and laterally, not sulcate.

Legs. Tarsal claws bidentate, with a basal lobe.

Wings (Fig. 7h). Forewings pubescent with moderately long marginal setae, about as long as total body length. Radial cell closed, about 3.1 times as long as wide; areolet large but not well defined, anterior and basal veins inconspicuous. Rs+M inconspicuous. Basal cell with sparsely spaced setae.

Metasoma (Fig. 7g). Slightly shorter than head plus mesosoma and slightly higher than long in lateral view. First metasomal tergum crescent-shaped and smooth. Second metasomal tergum short and free, almost 0.3 times as long as the metasomal length and faintly pubescent anterolaterally. Third metasomal tergum without punctures and not dorsodistally incised. Hypopygium finely punctate, long and projected above the upper surface of the metasoma. Prominent part of the hypopygial spine short and not projected, about as long as wide.

Male. Not examined (presumably lost).

Distribution. USA (state of Washington D.C.) according to Burks (1979), and Canada (Quebec) according to Provancher (1886: 164).

Biology. Reared from leaf petiole galls of Andricus quercuspetiolicola (Bassett, 1863) on Quercus michauxii Nuttall (= Q. prinus auctores not L., = Q. prinus var. michauxii (Nutt.) Chapman 1860) (Quercus section) (Osten- Sacken 1861); probably also from Neuroterus quercusbatatus (Fitch, 1859) according to Osten-Sacken (1865: 369, 371), but this record needs to be confirmed.

Remarks. Ceroptres petiolicola was presumably described from a single female (Osten-Sacken 1861: 67), although the same author later said his description ‘was based on one or two specimens only’ (Osten-Sacken 1865: 369); he also found two more specimens, a female and a male, so improving the original description a little. However, we only located and examined a type female of C. petiolicola from Osten-Sacken’s collection deposited in MCZ, and Osten-Sacken does not give any relevant clue on males.

The female of Ceroptres petiolicola examined is pierced through the mesosoma, which prevents us from analyzing some morphological traits of importance for the taxonomy of the genus (notauli, median groove, etc.). In addition, it shows some color differences with respect to the original description (C. petiolicola is mainly black to dark brown according to Osten-Sacken 1861: 67), which could be the result of a discoloration process.

Despite being very similar, differences between C. petiolicola and C. catesbaei do not allow us to assume that they are the same species (see the remarks section of C. catesbaei).