Stictococcus Cockerell

Williams, Douglas J., Matile-Ferrero, Danièle & Miller, Douglass R., 2010, A study of some species of the genus Stictococcus Cockerell (Hemiptera: Sternorrhyncha: Coccoidea: Stictococcidae), and a discussion on Stictococcus vayssierei Richard, a species injurious to cassava in Equatorial Africa with a description of a new species from Nigeria, Zootaxa 2527, pp. 1-27 : 9-10

Stictococcus Cockerell

Stictococcus Cockerell, 1903: 64 ; Morrison & Morrison, 1966: 188; Richard, 1971: 571, 1976: 656; Miller et al. 2005: 540.

Type species: Stictococcus sjostedti Cockerell & Cockerell , by monotypy.

Description of features of adult females of Stictococcus

Adult female in life broadly oval, becoming convex or fairly flat, thickened and heavily sclerotized at maturity, usually dark to reddish brown; often shiny with marginal white wax and clumps or dots of white wax on dorsum. Dorsum often raised around margins by lateral edges of venter which form a narrow rim.

Slide-mounted teneral specimens membranous, mature specimens heavily sclerotized; broadly oval, sometimes almost rotund, often with 6 pairs of minute marginal clefts and a single cleft at apex of abdomen; each cleft usually associated with a minute sclerotized plate. Anus displaced to almost centre of dorsum, comprising a wide, oval sclerotized ring enclosing an anterior and posterior sclerotized rectangular plate, each with a few flagellate setae; posterior plate often with reticulated surface; a pair of elongate sclerotized areas also present lateral to rectangular plates; posterior end of ring often extended, forming a small lip; an internal winged sclerotized process opening on to cuticle also present either attached to lip or situated a short distance posteriorly. Antennae 5- or 6-segmented, tapering gradually, with flagellate setae; terminal segment with fleshy setae also. Legs well developed but short for size of body, with few setae; tibia either same length as tarsus or shorter; claw wide at base then narrowing abruptly to curved blunt tip; digitules disparate, one elongate, slender and longer than claw with small expanded tip, other widely expanded distally, fan-shaped with small finger-like projections. Tarsal digitules also disparate, outer digitule on margin, elongate, slender, with small expanded tip; other situated about midway along distal margin, widely expanded and similar to widely expanded claw digitule. Spiracles large, each with heavily sclerotized apodeme and sclerotized atrium containing minute papilla-like structures. Eyes conical and sclerotized. Vulva wide, surrounded by short spine-like setae and with longer stiff-pointed setae at least on anterior margin. Labium 2 segmented, with sclerotized bar-like structure extending from each side of basal segment to lateral edge of clypeolabral shield.

Dorsal surface with variable number of long or short barbed setae, sometimes tapering to a point or widely expanded distally, with finger-like or lobed projections, sometimes short and flower-shaped; other setae present, short, pointed, smooth and curved; sometimes long flagellate setae present around margins and elsewhere on dorsum. Pores usually abundant, often in whorls or circles, either trilocular or bilocular, of at least two sizes and sometimes of three sizes (rarely a few quadrilocular pores present). Sometimes minute shallow cup-shaped pores present, each with minute central projection. Quinquelocular pores present, either minute and extending forwards from apical abdominal cleft to a position almost opposite vulva, and in small numbers next to other clefts; or larger, present associated with dorsal depressions, these depressions sometimes shallow or spherical.

Ventral surface with marginal setae broad and heavily sclerotized, cylindrical or tapering gradually or widely expanded distally with varying numbers of small lobes, sometimes slender but stiff, tapering, and always noticeably separated and easily countable; short spine-like setae, either bluntly or sometimes sharply pointed, also present usually in mid regions and submargins; flagellate setae present in mid regions, and often long flagellate setae present around margins. Quinquelocular pores, same as minute type on dorsum, present in definite pattern (see section on patterns above). Bilocular and trilocular pores, each with wide rims, present submarginally. Minute tubular ducts present across segments and scattered around submargins.

Comments

Strickland (1951b) remarked that some species are difficult to separate in the field except for S. sjostedti , which, apparently, is characteristic in its appearance. Slide-mounted specimens often show variation in the numbers and shapes of the dorsal setae and in the ventral marginal setae. The descriptions of the species that follow are based mainly on the original material and on a few other specimens. Often the marginal ventral setae are variable. Sometimes specimens with widely-expanded setae also possess cylindrical setae near the clefts and sometimes there are a few types of marginal setae present but the species discussed are defined by the marginal ventral setae predominantly of one type. There are probably more species than those discussed here, but they can only be described from teneral specimens which are not always available. There is a great need of molecular studies of these species. Care should be taken when new species are described, therefore, to take into consideration the wide variation in some of the characters in any one species.

There are hundreds of slide-mounted specimens that were examined by Claude Richard in the collection of the Muséum national d’Histoire naturelle, Paris, and the identifications are indicated with a question mark. We have not had the opportunity to study them in detail. For example, there are specimens from The Central African Republic collected in 1973 on Manihot esculenta , and these possess a complete row of ventral marginal setae that are all widely expanded and many lobed distally but agree in other characters with S. vayssierrei .

The following descriptions and illustrations are based either on original material or on specimens that compare well with the type material.