Acanthococcus Signoret

Hodgson, Chris & Miller, Dug, 2010, A Review of the Eriococcid Genera (Hemiptera: Sternorrhyncha: Coccoidea) of South America 2459, Zootaxa 2459 (1), pp. 1-101 : 6-8

Acanthococcus Signoret

Acanthococcus Signoret 1875: 16 ; Williams 1985: 358–359. Type species Acanthococcus aceris Signoret 1875: 35–36 .

Generic diagnosis. Adult female ( Fig. 1 ). Surface covered in waxy ovisac. Dorsum. Derm membranous. Setae often enlarged and spinose but highly variable among species. Enlarged tubular ducts absent. Macrotubular ducts present throughout. Microtubular ducts present, of varied structure. Loculate pores rarely present. Cruciform pores absent. Anal lobes well developed and often sclerotised; frequently with teeth-like projections on inner margins. Median plate present. Anal ring well developed with pores and setae. Margin. Often clearly demarcated by a line of enlarged spinose setae. Venter. Setae often spinose near margin but hairlike elsewhere. Macrotubular ducts present, frequently of more than 1 type. Microducts, when present, usually restricted to near margins; similar to those on dorsum in structure. Loculate pores present, usually with 5 loculi. Cruciform pores usually present. Frontal lobes present; antennal tubercles absent. Antennae usually 6 or 7 segmented. Labium 3 segmented, basal segment with 2 pairs of setae. Legs well developed; claw and tarsal digitules with apical knobs; claw with denticle; hind legs usually with translucent pores. Vulva present between abdominal segments VII and VIII .

The species from the Neotropics currently included in this genus are found on a wide range of plant families.

Comment. Currently Acanthococcus has a world-wide distribution, but the identity and number of species that are closely related to the type species A. aceris will not be known until more detailed analyses are undertaken. Following the work of Cook & Gullan (2004), it is here considered that all species from the Neotropics currently placed in the genus Eriococcus are more appropriately placed in Acanthococcus (see Appendix 1) excluding those recently placed in Eriobalachowskya and Hempelicoccus (Kozár & Konczné Benedicty, 2008) . However, because most South American species in Eriococcus were placed in Acanthococcus by Miller and Gimpel (2000) or Kozár & Konczné Benedicty (2008), new combinations are required only for E. clapsae González , E. cuneifoliae González , E. divericatae González , E. pituilensis González and E. lahillei (Leonardi) ( González, 2009) , which become A. clapsae (González) n. comb., A. cuneifoliae (González) n. comb., A. divericatae (González) n. comb., A. pituilensis (González) n. comb. and A. lahillei (Leonardi) n. comb. There are currently 29 species of “ Acanthococcus ” known from this region (see Appendix 1) but this number is likely to be a considerable underestimate of the total fauna. For recent studies on the “ Acanthococcus ” species of the Neotropics, see Miller and González (1975), González (2008a, 2008b, 2009), Foldi and Kozár (2007), and Kozár and Konczné Benedict (2008). Based on recent molecular research, it is possible that none of the species currently placed in this genus from South America will remain there after careful analysis. None of the “ Acanthococcus ” species known from South America have been recorded as causing galls.

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First-Instar Nymph (of Acanthococcus aceris , sex not determined) ( Fig. 2 )

Mounted material. Body oval, more pointed at posterior end. Dorsum. Dorsal setae of 1 type, in 2 submedial lines, 2 mediolateral lines and around margin. Macrotubular ducts absent. Microtubular ducts conspicuous, with a bifurcate dermal orifice, scattered. Anal lobes weakly sclerotised or unsclerotised, without a serrate inner margin. Median plate present, unsclerotised, inconspicuous. Margin. Delineated by band of spinose dorsal setae. Venter. Setae of 1 type: hairlike, arranged in 4 pairs of longitudinal lines. Macrotubular ducts absent. Microtubular ducts absent. Loculate pores, each with 3–5 loculi, present in a very sparse longitudinal line mediolaterally. Cruciform pores few, submarginal on thorax. Antennae 6 segmented. Small frontal lobe present. Labium 3 segmented, basal segment with 2 pairs of setae. Legs without pores; tarsus much longer than tibia; tarsal digitules capitate; claw with an inconspicuous denticle; claw digitules similar both with small capitate apices.

Comment. The first-instar nymphs of this genus are similar to those of Icelococcus by having: (i) 3 pairs of longitudinal lines of dorsal spinose setae; (ii) similar microducts; (iii) submedial line of ventral loculate pores; (iv) median plate; (v) small frontal lobe; and (vi) cruciform pores restricted to thorax. These 2 genera differ as follows: Acanthococcus has ( Icelococcus character states in parentheses): (i) weakly sclerotised or unsclerotised anal lobes, not plate-like (heavily sclerotized and plate-like); (ii) 4 pairs of longitudinal lines of ventral setae on abdomen (3 pairs); and (iii) loculate pores primarily with 5 loculi (3 loculi).

Figures

FIGURE 1. Acanthococcus aceris Signoret. Adult female, where A = marginal spinose seta; B = dorsal microtubular duct; C = dorsal spinose seta; D = dorsal macrotubular duct; K = ventral loculate pore; L = cruciform pore; M = frontal lobe; N = claw of metathoracic leg; R = larger ventral macrotubular duct; S = intermediate-sized macrotubular duct, T = small macrotubular duct; V = ventral seta (modified after Williams, 1985).

FIGURE 2. Acanthococcus aceris Signoret. First-instar nymph, where A = marginal spinose setae; B = dorsal microtubular duct; C = small spinose seta; D = median plate; K1 = ventral loculate pore with 5 loculi; K2 = ventral loculate pore with 3 loculi; L = cruciform pore; M = frontal lobe; N = claw of prothoracic leg; V1 & V2 = ventral setae