Ambrysus brunneus Sites

Sites, Robert W., 2015, New taxa of Cryphocricinae (Heteroptera: Naucoridae) from the Guiana Shield: Hygropetrocoris Sites, n. gen. and two new species of Ambrysus Stål, Zootaxa 4033 (3), pp. 427-438 : 433-435

Ambrysus brunneus Sites NEW SPECIES

Figs. 4 , 5

Description. Macropterous female. HOLOTYPE, length 8.04; maximum width 4.24. General shape elongate, parallel-sided; widest across embolia ( Fig. 5 A). Overall dorsal coloration dark brown, scutellum and legs slightly lighter. Dorsal surface coarsely punctate. Ventrally, yellowish, darkening around perimeter.

Head. Head length 1.24; maximum width 1.80. Brown, with light spot on posterior margin at midline, coarsely punctate. Eyes convergent anteriorly, synthlipsis 0.84; thin band of cuticle along posterolateral margin of eye; eyes flat and not raised above level of vertex or pronotum. Anterior margin between eyes slightly convex, nearly straight, extending anteriorly in front of eyes 3% of head length; posterior margin between eyes strongly convex, extending posteriorly 35% of head length. Labrum width 1.4× the length, evenly rounded, with sparse long hairs. Labium with three visible segments, basal two segments yellowish brown, distal segment medium brown, extending 0.42 beyond labrum. Antennal proportions 5:13:18:14, length 0.50, elongate hairs on segment 4 and distal half of 3, segments 1–3 yellow, segment 4 brown.

Thorax. Pronotum coarsely punctate; transverse sulcus marking anterior border of transverse band in posterior 1/4; brown with light mark on midline at anterior margin of transverse band; lateral margins slightly convex, with row of elongate erect setae and short recumbent setae, explanate, strongly convergent anteriorly; posterior margin approximately straight in middle 2/3, lobed posteriorly in lateral third; anterior margin deeply concave to embrace convex posterior margin of head and eyes; posterolateral corners rounded; width 3.0× the length; length at midline 1.26; maximum width at posterolateral corners 3.80. Prothorax ventrally pruinose medially, with broad glabrous band along lateral margin in posterior half, glabrous band abruptly becoming narrower at midlength and gradually narrowing anteriorly; apices of propleura meeting broadly at midline, separated from level of prosternellum; propleuron dark in anterior half and posterior to oblique sulcus; propleuron with medial 2/3 of posterior margin with elongate golden setae, lateral 1/3 impubis. Probasisternum yellow, with sharp medial carina and generally appearing pruinose with row of setae lateral to carina. Prosternellum yellow, extending beneath apices of propleura. Scutellum entirely brown and coarsely punctate, triangular, width 1.8× the length, width 2.64, length 1.48. Hemelytra densely punctate. Claval commissure length 0.92. Embolium length 1.26, greatest width 0.62; lateral margin nearly straight in anterior 3/4, slightly convex posteriorly, dark brown becoming lighter anteriorly. Oblique suture connecting claval and embolar sutures near bases. Hind wings well developed. Mesobasisternum with midventral longitudinal tumescence with sulcus on midline; tumescence terminating posteriorly as acute mesosternellum. Metasternellum (= metaxyphus) transverse, subtriangular, with apex acute.

Legs. All leg segments brown dorsally and yellow ventrally, except prothoracic legs entirely brown. Profemur dorsally coarsely punctate; posterior margin with brush of elongate setae in basal 1/4, 2–3 short brown spines near distal end of brush; anterior margin with dense pad of setae without associated spines. Protibia and tarsus with occlusal inner surface flattened and with spatulate setae; tarsus immovable, one-segmented; pretarsal claw single, minute, triangular. Procoxa with cluster of stout, brown anteromedial spines. Meso- and metacoxae partially recessed into thorax, with broad longitudinal sulcus that can accommodate flexed femora. Meso- and metafemora with row of short, brown spines on anterior margin; spines restricted to basal half on mesofemur, nearly full length of metafemur. Meso- and metatibiae with ventrolateral, ventromedial, dorsolateral, and dorsomedial rows of stout reddish-brown spines; mesotibia dorsolateral and dorsomedial rows include combs of up to three spines; metatibia dorsolateral row includes 8–10 single spines; meso- and metatibiae with three comb rows of reddish-brown spines at apical rim ventrally. Meso- and metatibiae and -tarsi with long, pale swimming hairs; hairs profuse on metatibia and -tarsus. Meso- and metapretarsi with paired claws slender, curved, without basal tooth. Leg measurements as follows: foreleg, femur 1.92, tibia 1.56, tarsus 0.42; middle leg, femur 2.04, tibia 1.76, tarsomeres 1–3, 0.14, 0.25, 0.34; hind leg, femur 2.28, tibia 2.52, tarsomeres 1–3, 0.16, 0.38, 0.40.

Abdomen. Dorsally with connexiva III–VI exposed, VII–VIII concealed by wings; yellowish brown lateral margin slightly darker posteriorly; lateral margin smooth, with short recurved pale hairs, group of trichobothria near posterolateral corners. Posterolateral corners of II (visible ventrally) –V narrowly rounded to right angled, not spinose, VI–VII bluntly acute. Ventrally mostly yellow, darker around margins, pruinose, with pile of fine hairs. Longitudinal band of elongate golden brown hairs beginning on midline of III, widening posteriorly to anterior half of VII (subgenital plate). Lateral margin with thin, glabrous band. Glabrous patches on laterosternites II–VI. Posterior margin of laterosternite VI with strong, posteriorly-directed acuminate, digitate lobe ( Fig. 5 B). Subgenital plate with posterior margin concave at midline, rounded posterolateral lobes, sinuate lateral margin, and posteroventrally directed acute process near basal corner ( Fig. 5 C); tuberculate process basad of each rounded posterolateral lobe.

Male. Unknown.

Diagnosis and discussion. Of the congeners in the region, this species superficially is most similar to Ambrysus stali La Rivers (see Sites & Reynoso-Velasco 2015). It can be distinguished by the smaller size, proportionately narrower shape, concolorous dark head and pronotum, shape of the subgenital plate, and the digitate process of laterosternite VI. The anterior margin of the pronotum is more or less continuously concave between the anterolateral corners, rather than having the concavity pronounced between the eyes as in most other species of Ambrysus . Only one specimen was collected. The label data indicate that it was collected in the same habitat with Hygropetrocoris guyana , although in part because of its hydrodynamic body form, it was most likely collected in a small pool or rootmats associated with the main water flow (left side of Fig. 4 A).

Etymology. The specific epithet is in reference to the solid brown dorsal color of the species.

Repository. The holotype is deposited in the Center for Biological Diversity, University of Guyana .

Material examined. HOLOTYPE ♀. GUYANA : Region 9, Kusad Mts., Mokoro Creek near rockslide area, 2° 48' 31.86", -59° 51' 54.0066", 170 m, 27 October 2013, Short, Isaacs, Salisbury, hygropetric seepage with detritus, GY 13-1027-03 B.

Figures

FIGURE 4. Type locality of Hygropetrocoris guyana n. gen. and Ambrysus brunneus n. sp. showing (A) general habitat and (B) specific habitat of H. guyana, which is in the center of the bedrock of Fig. 4 A. A. brunneus most likely was collected in small pools or rootmats of the vegetation on the left margin of the bedrock.

FIGURE 5. Ambrysus brunneus n. sp. (A) dorsal habitus; (B) terminal abdominal sterna, yellow arrow indicates digitate lobe of laterosternite VI; (C) subgenital plate (colored) with remainder of terminal segments (grayscale).