Coccus salicis

Williams, D. J. & Z. - Q, 2007, Carl Linnaeus and his scale insects (Hemiptera: Coccoidea) *, Zootaxa 1668 (1), pp. 427-490 : 456-459

Coccus salicis (Family Diaspididae ) [now known as Chionaspis salicis (L.)]

( Figure 9 )

Description

Adult female in life covered in a white pyriform scale, sometimes tinged with yellow, with yellow-brown exuviae of previous instars situated at anterior end. Body of adult female purplish, also pyriform. Scale of male much smaller, white, elongate with almost parallel sides.

Slide-mounted specimens of adult female, pyriform, membranous, with rounded pygidium. Legs absent. Antennae each tubercle-like, with a single seta. Anal opening situated a little anterior to middle of pygidium. Anterior spiracles each with 4–15 pores, each with 3 loculi. Lobes numbering 3 pairs. Median lobes largest, rounded, either close together or diverging from base, with short basal yoke. Second lobes bilobed, inner lobule often with 1 or 2 notches on outer margin, inner lobule smaller, also sometimes with 1 or 2 outer notches. Third lobes smaller than second lobes, rounded. Paraphyses minute, usually present at inner and outer bases of median and second lobes. Gland spines absent between median lobes, but usually present singly between median and second lobes and between second and third lobes; usually in pairs lateral to third lobes, and more numerous on ventral margins on abdominal segments IV and V, becoming smaller and more numerous anteriorly as far forward as abdominal segment I. Marginal macroducts present singly between median and second lobes and second and third lobes and lateral to third lobes but sometimes in pairs; usually present also in marginal and submedial groups on abdominal segments I–V with submedial group on segment VI; size of ducts varying considerably, sometimes many macroducts replaced by much smaller ducts, these also present marginally as far forward as prothorax. Microducts present on venter of mesothorax and metathorax and sometimes laterally on many abdominal segments; also present on submargins and submedial areas of pygidium but numbers variable. Perivulvar pores present in 5 compact groups.

Comments

This species is not represented in Linnaeus’ collection and the descriptions in Linnaeus (1758, 1767) without references to other authors would barely be accepted to validate the name except for the word “inconspicuous”. The description in Linnaeus (1761) (q.v.) is more detailed and certainly leaves us in little doubt about the identity of the species. Coccus salicis was first transferred to the genus Chionaspis Signoret by Signoret (1869) where it has remained.

There is considerable variation of characters in this species as shown by Danzig (1970), Takagi (1985) and Miller & Davidson (2005). The species is common and it is known on many woody plant species in the Holarctic Region. There are good accounts of the species in Newstead (1901), Balachowsky (1954), Danzig (1980), Kosztarab & Kozár (1985), Takagi (1985) and Miller & Davidson (2005). For full synonymy, distribution and host-plant range see Miller & Gimpel (2007a).

The accompanying illustration is reproduced from Balachowsky (1954) with the kind permission of Micheline Terquem, Institut Pasteur, Paris.

Coccus tiliae (Family Coccidae ) [now known as Eulecanium tiliae (L.)]

( Figure 10 )

Description

Adult female in life becoming highly convex at maturity, often turning dark brown and sometimes with a purplish tinge. Largest specimens about 5 mm in diameter and up to 5 mm in height.

Slide-mounted specimens of adult female soon after final moult, almost circular with anal cleft fairly wide apart; stigmatic clefts not developed, body membranous except for distinctive sclerotized area with radiating lines surrounding anal plates. Antennae each normally with 5 or 6 segments small for size of body. Legs well developed but also small for size of body; tibia and tarsus sometimes fused or divided but not articulated. Claw sometimes with denticle and with knobbed digitules. Anal plates together quadrate, each plate with anterior edge normally straight, posterior edge usually rounded, with 3 or 4 apical flagellate setae and 1 or 2 setae on inner margin.

Dorsal surface of body with short pointed setae, fairly numerous. Minute flat pores present, numerous. Tubular ducts each with slender ductule, scattered but more frequent marginally.

Ventral surface with stigmatic setae present in normal positions opposite each spiracle, each group with 3 bluntly-pointed thick setae, all more or less similar in size. Other marginal setae present, slightly thinner than stigmatic setae, blunt and tapered, replaced usually at anterior end and on apparent anal lobes with longer flagellate setae. Medial setae short and flagellate except for long pregenital setae. Multilocular disc pores present and abundant medially in bands on abdomen and on mesothorax and metathorax; groups also present medially to procoxae and next to antennal bases. Quinquelocular pores present in more or less single rows between spiracles and stigmatic setae. Microducts numerous in a submarginal band. Tubular ducts present in a wide submarginal band and around mouthparts, each duct with a well-developed cup and long ductule. Other tubular ducts, each with shallow cup, present in medial areas.

Comments

This species is absent from Linnaeus’ collection but Linnaeus (1758) referred to three figures in Réaumur (1740) thus validating the name and there can be little doubt about the identity of the species. Included among many synonyms of this species is C. capreae L. discussed above, a name synonymised by Lindinger (1912). For a full synonymy see Ben-Dov (1993, 2007). Coccus tiliae was first included in the genus Eulecanium Cockerell under some of its synonyms and the first combination of E. tiliae (L.) was made by Fernald (1903). The genus Eulecanium was placed on the Official List of Generic Names in Zoology, Name Number 2245 with the type species Coccus tiliae L. by Melville (1985). The specific name tiliae as published in the binomen Coccus tiliae L. was placed on the Official List of Species Names in Zoology with the Name Number 2940, also by Melville (1985).

Eulecanium tiliae is known from a long list of woody plants ( Ben-Dov, 2007) and is common throughout the Palaearctic Region and also known in North America and India. There are many descriptions of this species. For some of the most important see Newstead (1903) under Lecanium capreae (L.) (with coloured plate), Borchsenius (1957), Kosztarab & Kozár (1985) and Hodgson (1994).

The accompanying illustration is taken from Hodgson (1994) with the kind permission of the author and CABI Publishing.

Figures

FIGURE 9. Coccus salicis L. Adult female. (Now Chionaspis salicis (L.)).

FIGURE 10. Coccus tiliae L. Adult female. (Now Eulecanium tiliae (L.)).