Duadicus Dallas 1851

Wang, Xiao-Jing, Liu, Guo-Qing & Cassis, Gerasimos, 2014, Systematic study of Duadicus Dallas, 1851 (Insecta: Hemiptera: Heteroptera: Acanthosomatidae: Blaudusinae: Blaudusini), including the description of a new species from Western Australia, Austral Entomology 53 (1), pp. 42-52 : 43-44

Duadicus Dallas 1851

Duadicus Dallas 1851: 293 (gen. nov.); Stål 1876: 112 (list); Lethierry and Severin 1893: 251 (catalogue); Kirkaldy 1909: 169 (catalogue); Kumar 1974: 19, 34, 36, 39–40 (description); Cassis and Gross 2002: 370 (Australian catalogue)

Type species: Duadicus pallidus Dallas, 1851 by monotypy

Diagnosis

Duadicus is recognised by the following combination of characters: body yellow to reddish brown with contrasting markings; AI extending well beyond anterior margin of head; anterolateral margins of pronotum excavate, crenulate; posterior margin of pronotum weakly excavate medially, posterolateral angles produced; anterior third of embolium explanate; connexiva broadly exposed, banded yellow and reddish-brown; mesosternum with a weakly developed medial carina; abdominal spine very long, flat, reaching at least to posterior margin of forecoxae; and Pendergrast’s organs present on abdominal SVII.

Redescription

Body length 6.67–7.69 (Table 1). Colouration. Body pale to medium brown. Head: medium to dark brown, with contrasting reddish brown markings. Eyes: black. Antennae: AI-AIV medium brown, sometimes AI, apex of AII and AIII with reddish tinge; AV a little darker brown. Labium: LI-LIII pale to medium brown; LIV black. Pronotum: callus yellowish to medium brown; lateral margin of pronotum translucent; base of pronotal horn medium brown, with tip black or yellowish brown. Scutellum: medium to dark brown, with reddish brown markings; pale yellow at apex. Thoracic pleura: pale to yellowish brown with reddish markings. MTG: pale to yellowish brown. Hemelytra: pale to medium brown, with reddish brown markings; membrane transparent, sometimes with brown tinge at base. Legs: coxae and femora medium brown, with reddish markings on femora; tibiae pale brown, with reddish tinge at extremities; tarsi medium brown; claws medium brown at base, black apically. Abdomen: connexiva medium brown; spine pale to medium brown; venter pale to medium brown, with reddish markings. Vestiture. Dorsum with moderate distribution of simple white decumbent setae on lateral margin of head, pronotum and corium. Antennae: with simple short decumbent pale brown setae, almost uniform length on AI; AII-AIII with moderately distributed setae; AIV-AV densely distributed setae. Labium: with few simple short semi-erect setae of almost uniform length and distribution, denser at apex of LIV. Legs: setae on femora rare; setae on tibiae and tarsi more densely distributed, spinelike setae on tibiae; apex of tarsi with few hairlike setae. Abdomen: simple short decumbent pale brown setae distributed laterally; semi-erect setae moderately distributed. Structure. Head: paraclypei slightly concave laterally, not extending beyond anteclypeus. Eyes: almost semicircular in frontal view, with medial margin straight. Antennae: AI longest segment, extending well beyond anterior margin of head; AIII and AIV subequal in length; AV shortest segment. Labium: reaching mid coxae or a little beyond; LI slightly wider than other segments; LII about as wide as LIII; LIV slightly thinner than LII; LII longest, about 2× longer than LI; LIII slightly shorter than LII; LIV almost as long as LI. Pronotum: callus mostly rectangle, sometimes rounded; lateral margin of pronotum wavy, arcuate and upward; pronotal horns processed obviously. Scutellum: flat, width longer than length. MTG: suboval. Legs: metafemora slightly broader and longer than fore femora and mesofemora; tarsi narrow, tarsal segment I almost as long as segment II. Abdomen: connexiva posterior angles rounded; spine reaching beyond anterior margin of fore coxae, not reaching anterior margin of prosternum. Male genitalia: pygophore opening broad; two processes medially; posterodorsal rim sinuated, with a medial notch and sparse short setae; posteroventral rim concave; posterolateral angle rounded, with dense long setae; paramere ‘L’ shaped; apex slightly upturned; vesica ‘C’ shaped, sclerotised. Female genitalia: first gonocoxites large, platelike, posterior margins almost straight; eighth paratergite subtriangular; apices of ninth paratergites distantly removed from apices of eighth paratergites.

species Duadicus of Measurements 1 Table

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Species Length Width InterOcDist AI AII AIII AIV AV Total length Head Pronotum Scutellum Head Pronotum Scutellum D. namyatovae sp nov.

♂ (n = 3) Mean 7.38 1.06 1.78 2.24 1.83 5.76 2.72 0.58 1.22 0.89 0.85 0.91 0.83 SD 0.19 0.09 0.07 0.03 0.03 0.29 0.04 0.03 0.03 0.01 0.00 0.02 0.02 Range 0.37 0.17 0.15 0.05 0.06 0.58 0.07 0.05 0.05 0.01 0.01 0.04 0.04 Min 7.20 0.96 1.70 2.22 1.80 5.45 2.68 0.55 1.20 0.88 0.85 0.89 0.81 Max 7.57 1.13 1.85 2.28 1.86 6.03 2.75 0.61 1.25 0.90 0.86 0.93 0.85 D. pallidus ♂ (n = 5) Mean 7.14 1.02 1.63 2.00 1.62 5.73 2.44 0.47 1.09 0.87 0.77 0.77 0.71 SD 0.34 0.07 0.09 0.06 0.06 0.30 0.13 0.02 0.12 0.06 0.07 0.05 0.09 Range 0.79 0.16 0.22 0.17 0.14 0.77 0.34 0.04 0.28 0.14 0.19 0.12 0.22 Min 6.67 0.94 1.52 1.91 1.55 5.37 2.30 0.45 0.93 0.80 0.67 0.70 0.57 Max 7.45 1.10 1.75 2.08 1.69 6.14 2.64 0.49 1.21 0.93 0.86 0.82 0.79 ♀ (n = 5) Mean 7.34 0.95 1.70 2.13 1.68 6.05 2.56 0.52 0.96 0.85 0.68 0.71 0.65 SD 0.28 0.15 0.09 0.11 0.07 0.41 0.17 0.04 0.07 0.05 0.03 0.03 0.01 Range 0.64 0.37 0.17 0.27 0.18 1.13 0.45 0.09 0.15 0.11 0.06 0.06 0.03 Min 7.05 0.79 1.64 1.95 1.62 5.44 2.38 0.47 0.87 0.80 0.64 0.67 0.63 Max 7.69 1.15 1.80 2.22 1.80 6.57 2.83 0.56 1.02 0.91 0.71 0.73 0.66

Distribution

Duadicus is endemic to temperate Australia.

Host plants

There has been limited data on the host plant associations of acanthosomatids on a worldwide basis. Yamamoto et al. (2009) recorded 70 host plant species from 20 plant families for 25 of the Japanese acanthosomatid species. Cassis and Gross (2002) gave notes of known Australian known host plants, including new records for D. pallidus . In this work we record host plant records from recent survey work ( Cassis et al. 2007) for both Duadicus species that demonstrate multiple occurrences with Melaleuca (see species treatments).

Remarks

Kumar (1974) assigned Duadicus is similar to Andriscus Stål but can be readily distinguished from it by the following characters: (1) AI extends considerably beyond the anterior margin of the head and is subequal to length. In Andriscus the first antennal extends only slightly beyond the anterior margin of the head and is less than half the length of the head; (2) the lateral margins of the pronotum are sinuate and are arcuate posteriorly. In Andriscus the lateral margins of the pronotum are almost straight.

Key to species of Duadicus Dallas , |85|

1 Dorsum medium brown, mostly with reddish tinge; lateral margin of pronotum arcuate obviously; pronotal horns strongly projected, with apex black................ ............................................. D. pallidus Dallas Dorsum pale brown, no reddish tinge; lateral margin of pronotum almost straight; pronotal horns weakly projected, with apex yellow ..................................... ...................................... D. namyatovae sp. nov.

Figures

species Duadicus of Measurements 1 Table