Acanthococcus gallicolus (Cockerell & Rohwer) Miller & Stocks, 2022

Miller, Douglass R. & Stocks, Ian C., 2022, New genera and species of felt scales (Hemiptera: Coccomorpha: Eriococcidae), with descriptions of new species and immature instars of described species, Zootaxa 5221 (1), pp. 1-213 : 19-24

Acanthococcus gallicolus (Cockerell & Rohwer) comb. n.

Atriplicia gallicola Cockerell and Rohwer 1909: 169 .

Eriococcus gallicola (Cockerell & Rohwer) ; Lindinger 1914: 116 (change of combination and misspelling of species epithet). Nidularia gallicola (Cockerell & Rohwer) ; Lindinger 1933a: 113 (change of combination).

Eriococcus gallicolus Ferris 1957: 85 (revived combination requiring emendation of specific epithet for agreement in gender).

Type material: We have examined two series of specimens (received at USNM October 30, 1908 and November 9, 1908 from L.C. Bragg) with identical information as the type series except they were sent to the USNM rather than to Cockerell and Rohwer. There is no doubt that these specimens are identical to the type series but were not used for the original description. We also have seen specimens collected by Townsend in 1896 that were mentioned by Cockerell and Rohwer (1909) in the original description of the species but were excluded from the type series.

Specimens examined: Locality ?: received at USNM V-?-1927, on Atriplex sp. , T.D.A Cockerell (2 ad. ♀♀ on 1 slide) USNM . UNITED STATES: California: Inyo Co.: Deep Springs , IX-27-1925, on Atriplex sp. , G.F. Ferris (2 ad. ♀♀ on 1 slide) UCD . Colorado: Las Animas Co.: Trinidad, received at USNM XI-9-1908, on A. canescens, L.C. Bragg (9 ad. ♀♀, 8 second-instar ♀♀ exuviae on 5 slides) USNM ; Trinidad , received at USNM X-30-1908, on A. canescens, L.C. Bragg (13 ad. ♀♀, 2 second-instar ♀♀, 2 first-instar nymphs on 9 slides) USNM . New Mexico: Dona Ana Co.: Las Cruces , X-9-1896, on A. canescens, C.H.T. Townsend (5 ad. ♀♀, 1 second-instar ♀ exuviae, 7 first-instar nymphs on 3 slides) USNM ; Mesilla Park , V-5-1909, on A. canescens, C.N. Ainslie (6 ad. ♀♀, 26 firstinstar nymphs on 4 slides) USNM .

Etymology: The species epithet “ gallicolus ” is formed from the Latin word “ galla ” meaning “gall” or “oak apple” and apparently refers to the gall induced by this species.

Field features: Acanthococcus gallicolus induces the leaf of the host to fold, forming a gall. According to Cockerell and Rohwer (1909: 170), “The gall, about 4.5 mm long, consists of the subglobular swollen base of the Atriplex leaf, the sides being folded upwards, leaving an open slit above, the margins of which are curled outward. The end of leaf makes a pointed process at the end of each gall.” According to Felt (1918), the galls are alternate on the host plant. Dried galls contain the exuviae of the second-instar female and the withered adult female, and are lined with a thin layer of wax similar to the secretion produced on the venter of many eriococcids.

Adult female ( Fig. 6 )

Description: Slide-mounted specimens, 0.9–2.4 mm long, 0.8–2.1 mm wide. Body rotund, with anal lobes protruding. Anal lobes each slender, apically acute, either lightly sclerotized or without sclerotization. Each lobe dorsally with 3 slender setae and no microtubular ducts; each lobe ventrally with 3 or 4 flagellate setae including suranal seta and anal-lobe seta and 0 or 1 multilocular pores.

Dorsum with all setae flagellate, without longitudinal lines, arranged in transverse rows on head to segment VII; of 1 variable size: largest seta about 7 μm long; segment IV with 10–13 setae. Macrotubular ducts in small numbers over surface. Microtubular ducts absent. Multilocular pores scattered over surface, of 3 kinds: 7-locular pores and 3-locular pores uncommon; 5-locular pores abundant. Cruciform pores absent. Microtrichia present from segment III or IV to VIII.

Anal ring normally bent around posterior apex of abdomen, usually with 4 setae on each side of ring, suranal setae flagellate. Anal tube without sclerotization or weakly sclerotized.

Venter with flagellate setae noticeably longer than those on dorsum, setae on segment II 85–122 μm long, on segment VII 61–82 μm; anal-lobe seta 162–270 μm long; setae apically acute. Enlarged setae absent. Macrotubular ducts smaller than those on dorsum, on abdomen only. Microtubular ducts absent. Multilocular pores with 5-loculi only, scattered over entire surface, most abundant near vulva. Cruciform pores absent. Large numbers of weakly indicated pores on metathorax and anterior abdominal segments, surrounding hind pair of legs. Legs with hind coxae dorsally each with 0–6 pores, absent ventrally; each femur with 5 setae; each tibia with 5 setae, 1 in middle of tibia; tibia/tarsus 0.7–1.0; claws each with denticle near tip; tarsal and claw digitules apically capitate. Antennae each 7-segmented, rarely with 6, 189–208 μm long. Frontal lobes absent. Preantennal pore present. Microtrichia present on all coxae; in medial areas of segment II to VIII, sometimes absent.

Notes: The description is based on 33 specimens from six localities. The adult female of A. gallicolus is unique in lacking dorsal enlarged setae, dorsal microtubular ducts, and in having dorsal multilocular pores and numerous pores on the derm next to the hind coxae.

As is the case for many gall-inducing species of eriococcids, the morphology of Ac. gallicolus appears to have evolved to accommodate living in a different microhabitat. The main character state separating this species from other Acanthococcus species is the absence of enlarged setae. The enlarged setae of species of Acanthococcus serve as the base of crystalline wax rods that may function in camouflaging the species or in protecting it from natural enemies. In the case of Ac. gallicolus , the enlarged setae apparently have been lost because their utility would seem to be unnecessary within the confines of a gall. Since the first-instar nymph of Ac. gallicolus is nearly identical to the first-instar nymphs of many other North American species of Acanthococcus we agree with Lindinger (1914) and Ferris (1957) and consider Atriplicia to be a junior subjective synonym, in this case of Acanthococcus , not Eriococcus .

Second-instar female ( Fig. 7 )

Description: Slide-mounted specimens each 0.9 mm long, 0.6 mm wide. Body pear-shaped, with protruding anal lobes. Anal lobes narrow and pointed, lightly sclerotized on both surfaces, each lobe dorsally with 3 flagellate setae, each lobe ventrally with 3 or 4 flagellate setae including suranal seta and elongate anal-lobe seta.

Dorsum with all setae flagellate, scattered over head and anterior thorax, arranged in 3 pairs of longitudinal lines (medial, sublateral and lateral), from posterior thorax to segment VII; of 2 sizes, largest 10–12 μm long on abdomen, smallest on head and thorax about 5 μm long; segment IV with 7 or 8 setae. Microtubular ducts each about 3 μm long, with area farthest from dermal orifice sclerotized and divided into 2 parts, apical portion rounded and about ½ length of remaining sclerotized portion; when present restricted to segment VIII. Multilocular pores of 5-locular kind only, scattered over entire surface. Cruciform pores absent. Microtrichia present on segments II to VIII.

Anal ring apical, with 3 setae on each side of ring, suranal setae flagellate. Anal tube without sclerotization.

Venter with longest flagellate seta on segment II about 43 μm long, on segment VII about 36 μm; anal-lobe seta 102–196 μm long; setae apically acute. Enlarged setae absent. Microtubular ducts absent. Multilocular pores scattered over entire surface, of 2 kinds: 5-locular pores most abundant; 3-locular pores rare. Legs with each femur with 5 setae; each tibia with 5 setae, with 1 in middle; tibia/tarsus 0.7–0.8. Antennae each 6-segmented, 108–147μm long. Frontal lobes absent. Preantennal pore present. Microtrichia present on coxae, absent elsewhere.

Notes: The description is based on 11 specimens from two localities. The illustration and description are based on exuviae and may have some discrepancies. The second-instar female of Ac. gallicolus is unique in lacking dorsal enlarged setae, and in having dorsal multilocular pores.

First-instar nymph ( Fig. 8 )

Description: Slide-mounted specimens 0.4–0.5 mm long, 0.2–0.3 mm wide. Body slightly pear-shaped, with protruding anal lobes. Anal lobes broad, apically acute, lightly sclerotized; each lobe dorsally with 3 enlarged setae (anteromedial seta normally shortest, posteromedial and lateral setae equal, rarely all setae equal), microtubular ducts usually absent from lobes, each lobe ventrally with 3 or 4 slender setae including suranal seta and anal-lobe seta.

Dorsum without flagellate setae; enlarged setae arranged in 3 pairs of longitudinal lines (medial, mediolateral and lateral), on thorax and abdomen, with no additional setae between lines except on head; setae of 1 variable size, becoming smaller anteriorly, present in transverse rows from head to segment VII; setae straight or slightly curved, with slightly rounded apices; segment IV with 6 setae. Macrotubular ducts absent. Microtubular ducts with area farthest from dermal orifice sclerotized and divided into 2 parts, apical portion rounded and about ½ length of remaining sclerotized portion; total sclerotized area longer than unsclerotized area; dermal orifice unsclerotized. Microtubular ducts on abdomen associated with mediolateral pairs of enlarged setae forming 1 pair of longitudinal lines; on thorax and head microtubular ducts associated with medial or mediolateral and lateral pairs of enlarged setae forming 2 pairs of longitudinal lines. Multilocular and cruciform pores absent. Microtrichia present on segments IV to VIII.

Anal ring apical, with 3 setae on each side of ring, suranal setae flagellate. Anal tube without sclerotization.

Venter with body setae flagellate, longest seta on segment II approximately 11 μm long, on segment VII about 19 μm; longest anal-lobe seta 100–171 μm long. Enlarged setae on lateral margins of segments VI and VII and near spiracles. Macrotubular ducts absent. Microtubular ducts absent. Multilocular pores of 2 kinds: 5-locular pores most numerous; 3-locular pores uncommon but present on all specimens examined; distribution of these pores relatively constant, rarely with pore near anterior margin of metathoracic pairs of legs, otherwise same as in illustration. Cruciform pores absent. Legs with each femur with 5 setae; each tibia with 5 setae, 1 seta in middle; tibia/tarsus 0.7– 0.8. Antennae each 6-segmented, 104–161 μm long. Frontal lobes absent. Preantennal pore present. Microtrichia absent from coxae, present in medial areas of segments IV to VIII.

Notes: The description is based on 37 specimens from three localities. The first-instar nymph of Ac. gallicolus is most similar to the first-instar nymph of Ac. arenosus in having five setae on each hind tibia and five setae on each hind femur. They differ as follows (character states of Ac. gallicolus are given in brackets): medial and mediolateral enlarged setae smaller than the lateral enlarged setae (about the same size as the lateral setae); cruciform pores usually present (absent).

Figures

FIGURE 6. Acanthococcus gallicolus (Cockerell and Rohwer 1909), adult female, Trinidad, Las Animas Co., Colorado, USA: received at USNM September 9, 1908, on Atriplex canescens, L.C. Bragg. C=7-locular pore; D=5-locular pore; E=3-locular pore; G=macrotubular duct; L=claw; O=femur; CC=weakly indicated pore.

FIGURE 7. Acanthococcus gallicolus (Cockerell and Rohwer 1909), second-instar female, Trinidad, Las Animas Co., Colorado, USA: received at USNM September 9, 1908, on Atriplex canescens, L.C. Bragg. D=5-locular pore; E=3-locular pore; F=microtubular duct; L=claw; Q=dorsal surface of coxa; W=hind leg.

FIGURE 8. Acanthococcus gallicolus (Cockerell and Rohwer 1909), first-instar nymph, Mesilla Park, Dona Ana Co., New Mexico, May 5, 1909, on Atriplex canescens, C.N.Ainslie.A=enlarged seta; D=5-locular pore; E=3-locular pore; F=microtubular duct; L=claw.