Coccus quercus, Linnaeus, 1758

Williams, D. J. & Z. - Q, 2007, Carl Linnaeus and his scale insects (Hemiptera: Coccoidea) *, Zootaxa 1668 (1), pp. 427-490 : 452-454

Coccus quercus (Family Kermesidae )

( Figures 5B , 7 )

Description

Body of mature female almost globular, reniform, dark brown, usually found in crevices of bark.

Adult female before maturity on microscope slide ( Fig. 7 ), round, 3–5 mm in diameter, with much of dorsum overlapping on to apparent venter. Medial areas of actual venter invaginated. Antennae short, tapering, 4 segmented. Legs small for size of body. Labium 3 segmented.

Dorsum with short spine-like setae, some at anterior end surrounded by quinquelocular pores. Macrotubular ducts present around anterior areas of venter except in medial area; present also at anterior end of dorsum; others sparse and scattered on dorsum. Quinquelocular pores present near spiracles and surrounding setal collars. Multilocular disc pores present on venter across abdominal segments in invaginated area.

First instar-nymph ( Fig. 5B ) on microscope slide, with body oval, slightly constricted at posterior end and with anal lobes poorly developed, each with a long flagellate seta. Antennae 6 segmented. Legs well developed, claws each with knobbed digitules and without denticle. Labium 3 segmented, about as long as clypeolabral shield. Anal ring situated near apex of venter, inverted horse-shoe-shaped, cellular with 4–6 short setae.

Dorsal surface with marginal and submedial longitudinal rows of enlarged setae except for slender and pointed setae submedially on abdominal segments V–VII. Minute simple circular pores present, sparse on head and thorax and singly near marginal and submedial rows of setae.

Ventral surface with short setae. Quinquelocular pores present, normally 2 associated with each anterior spiracle and 1 or 2 associated with each posterior spiracle, occasionally a quinquelocular pore replaced by a trilocular pore. Other slightly larger quinquelocular pores represented medially in pairs on pro- and mesothorax. Minute bilocular pores located singly on margins of mesothorax and metathorax.

Comments

When giving a short account of the habit of this species on Quercus robur, Linnaeus (1758) included a reference to figures in Réaumur (1740) and this validated the name. Specimens are absent from Linnaeus’ collection. The first indication that the name Coccus quercus should be included in the genus Kermes Boitard was made by Cockerell (1894) but, for some reason, Cockerell listed it as Kermes quercus Newst. M.S. an African species. This species has never been recorded from Africa and the first combination Kermes quercus (L.) should be credited to Cockerell (1899b). It has remained there since except that some authors, such as Henriksen (1921) and Borchsenius (1960), have placed it in the genus Kermococcus Silvestri , an unjustifiable replacement name. The adult female at maturity is difficult to study when heavily sclerotized and a new description based on newly moulted adults is needed. First-instar nymphs are usually studied to separate the species. There are descriptions of this species by Newstead (1903) (adult female), Borchsenius (1960) (adult female and first instar), Balachowsky (1950) (first instar), Kosztarab & Kozár (1988) (adult female) and Podsiadło (2005) (first instar). Bullington & Kosztarab (1985) gave a good account of the study of the invaginated ventral surface of North American species. Kermes quercus is widespread in the western Palaearctic region on Quercus robur . For full synonymy and references to this species see Miller et al. (2005).

The accompanying illustration of the adult female ( Fig. 7 ) is reproduced from Borchsenius (1960) except that it has been reversed to show the dorsum on the left. The illustration of the first-instar nymph is here taken from Podsiadło (2005) with her kind permission and permission from Professor J. Banaszek, Editor in Chief, Polske Pismo Entomologiczne.

Figures

FIGURE 5 A. Coccus ilicis L. First-instar nymph. (Now Kermes ilicis (L.)) B. Coccus quercus L. First-instar nymph. (Now Kermes quercus (L.)).

FIGURE 7. Coccus quercus L. Adult female. (Now Kermes quercus (L.)).