Acanthococcus riojensis Juárez & González, 2017

González, Patricia, Claps, Lucía E., Juárez, Andrea & Moreno, Diego, 2017, Review of the Eriococcidae (Hemiptera: Coccomorpha) infesting Fabaceae in Argentina, with descriptions of three new species of Acanthococcus Signoret, Zootaxa 4232 (1), pp. 41-57 : 46-50

Acanthococcus riojensis Juárez & González sp. nov.

Type material. Holotype: female located towards the right of the preparation, marked with a red circle. Argentina, La Rioja, road to Chilecito (29°13'21" S, 67°29'13" W), 28/IV/1991, on Acacia, M.C.G. Willink col., 1(2) ( IFML) . Paratypes: 1 (1+2 second-stage female nymphs, with same data as holotype slide) ( IFML) .

Species diagnosis, adult female ( Fig. 3 ). Dorsal setae conical and numerous; macrotubular ducts symmetrical; microtubular ducts of both types A and B present. Margin with single conical seta on each abdominal segment. Ventral surface with a line of small, conical setae in submargin; microtubular ducts of both types present, sparse; legs long and slender; metathoracic coxae with sparse pores.

Description. Body of slide-mounted adult female oval, 1.59 (1.35–1.50) mm long, 0.80 (0.73–0.80) mm wide. Anal lobes enlarged, partially sclerotized, each about 98 (58) µm long, 49 (43) µm wide; dorsal surface with 3 conical setae: inner posterior seta about 43 (41) µm, inner anterior seta about 41(50) µm, outer seta about 24 (29) µm long; ventral surface with 2 flagellate setae, anterior about 65 (48) µm and posterior about 72 (84) µm long; apical setae each about 179 (177) µm long. Medial plate absent.

Dorsal surface: with straight or slightly curved conical setae, each with slightly rounded apices; variable in size, each 19–53 (19–49) µm long, larger setae on margin and in lateral and medial longitudinal lines, latter reaching as far posteriorly as abdominal segment V. Smaller conical setae distributed over thoracic and abdominal surface and medially on segments VI, VII and VIII. Microspinules present medially on abdominal segments. Macrotubular ducts symmetrical, barely visible, each about 14 (14) µm long, 5 (5) µm wide. Microtubular ducts distributed over entire surface and on margin, of both types A and B present, type A most numerous. Anal ring with 6 setae, each 50–79 (62–89) µm long, with a single row of pores.

Margin: with one conical seta on either side of each abdominal segment, each about 48 (36) µm long; setae undifferentiated from dorsal setae on thorax and cephalic region.

Ventral surface: setae of three types present: flagellate setae, abundant over entire ventral surface, of variable length, each 36–72 µm, longest between antennae; straight conical setae, of similar size to those on dorsum, each 12–19 µm long, present along sub-margin; and small, marginal spinose setae, each 12–19 µm long, extending from cephalic region to about abdominal segment V. Suranal setae flagellate. Microspinules present medially on abdominal segments. Quinquelocular pores present on abdominal segments, each about 5 (5) µm diameter; also sparsely present near spiracles and antennal bases; trilocular pores restricted to near spiracles. Cruciform pores sparse submarginally on thoracic segments, extending posteriorly to abdominal segment IV. Macrotubular ducts sparse, each about 12 (12) µm long, 5 (5) µm wide. Microtubular ducts of both type A and B present, sparse on thorax and margin, absent elsewhere. Spiracles each about 48 (38) µm long, 24 (24) µm wide. Legs well developed, large but slender; all claws each with a denticle; tarsal and claw digitules equal-sized. Prothoracic legs: coxa about 108 (108) µm long; trochanter + femur about 168 (144) µm; tibia about 100 (84) µm, with 5 setae; tarsus about 115 (108) µm; claw about 36 (31) µm long. Mesothoracic legs: coxa about 144 (72) µm long, with microspinules; trochanter + femur about 199 (156) µm; tibia about 125 (103) µm; tarsus about 132 (120) µm; claw about 36 (31) µm long. Metathoracic legs: coxa about 120 (103) µm long, with microspinules and about 10 irregularly-shaped pores; trochanter + femur about 211 (168) µm; femur with 4 setae, without pores; tibia about 139 (108) µm, with 4 setae; tarsus about 149 (103) µm; claw about 36 (36) µm long. Antenna about 205 (210) µm long, with 7 segments; third segment longest, without setae. Frontal lobes present, smaller than first antennal segment. Labium 3 segmented, basal segment with two pairs of setae. Anal tube sclerotized.

Comments. Acanthococcus riojensis sp. nov. resembles A. microspinus Kozár & Konczné Benedicty in the types of setae, the presence of frontal lobes and the presence of small medial setae on the posterior abdominal segments ( Kozár & Konczné Benedicty 2008). However, the two species differ in that A. microspinus exhibits (character-states for A. riojensis in brackets); (i) larger dorsal setae, each 36–67 µm long (19–53 µm long); (ii) larger dorsal setae not forming longitudinal lines (forming longitudinal lines); (iii) only one type of microtubular duct (two types), and (iv) a 2-segmented labium (3 segmented).

Second nymphal instar (considered to be male) ( Fig. 4 ).

Description. Body mounted on slide oval, 1.0 (1.0–1.2) mm long, 0.5 (0.5–0.97) mm wide. Anal lobes enlarged; dorsal surface with 3 conical setae: inner posterior seta about 36 (36) µm long, inner anterior seta about 36 (36) µm long and outer seta about 19 (24–29) µm long; ventral surface with two flagellate setae, anterior seta about 36 (53) µm, posterior seta about 53 (60) µm long; apical seta very long, about 168 (168) µm. Medial plate absent.

Dorsal surface: setae conical, slender, straight or slightly curved, with slightly rounded apex, varying in size, each 12–36 (19–36) µm long, similar to or smaller than marginal setae, smallest setae present submarginally and interspersed amongst largest setae. Macrotubular ducts symmetrical, each about 14 (14) long, 5 (5) µm wide, very sparse and barely visible. Microtubular ducts of type B present on margin and dispersed sparsely throughout. Anal ring with 6 setae, each 67–80 (67–84) µm long, and a single row of pores.

Margin: with one marginal seta on either side of each abdominal segment, similar in size to larger dorsal setae.

Ventral surface: flagellate setae present throughout, each 12–53 (19–60) µm long. Straight conical setae present submarginally along entire margin, each 14–30 (19–36) µm long. Quinquelocular pores each about 5 (5) µm in diameter, and trilocular pores present on abdominal segments and near each spiracle. Cruciform pores sparse marginally on thoracic segments. Macrotubular ducts present sparsely near margin, each about 12 (12) µm long, 5 (5) µm wide. Microtubular ducts absent. Spiracles each about 43 (36) µm long and 26 (24) µm wide. Legs welldeveloped, long and slender; all claws each with a denticle; tarsal and claw digitules equal-sized. Prothoracic legs: coxa about 96 (106) µm long; trochanter + femur about 124 (127) µm; tibia about 79 (94) µm, with five setae; tarsus about 100 (103) µm; claw about 29 (26) µm long. Mesothoracic legs: coxa about 84 (108) µm long; trochanter + femur about 156 (151) µm; tibia about 103 µm; tarsus about 120 µm; claw about 31 µm long. Metathoracic legs: coxa about 96 (103) µm long; trochanter + femur about 156 (175) µm; femur shorter than tarsus, with 4 setae; tibia about 108 (110) µm, tarsus about 132 (139) µm; claw about 31 (36) µm long. Meso- and metacoxae both with microspinules. Antenna 7 segmented, about 175 (192) µm long, third segment longest, about 31 (31) µm. Labium 3 segmented, basal segment with 2 pairs of setae. Anal tube sclerotized.

Observations. Usually, second-instar male Acanthococcus have macrotubular ducts and 7-segmented antennae, and second-instar females lack macrotubular ducts and have 6-segmented antennae ( Miller et al. 1992, Hodgson & Trencheva 2008, Kozár et al. 2008). Based on these characters, we consider our specimens to be like second instar males, although one of the second-stage nymphs has large, irregular pores on the metathoracic coxae, a character present in adult females.

Distribution. Argentina, South American Transition Zone, Monte province.

Etymology. The name riojensis refers to the province La Rioja, in Argentina, where the species was found.

Figures

FIGURE 3. Acanthococcus riojensis Juárez & González sp. nov. Adult female. A: microduct type A; B: microduct type B; C: conical seta; D: flagellate seta; E: enlarged conical ventral seta; F: marginal spinose seta.

FIGURE 4. Acanthococcus riojensis Juárez & González sp. nov. Second-instar nymphal male. B: microduct type B; C: conical seta; D: flagellate seta; E: enlarged conical ventral seta.