Siamgryllacris rufa, 2018

Ingrisch, Sigfrid, 2018, New taxa and records of Gryllacrididae (Orthoptera, Stenopelmatoidea) from South East Asia and New Guinea with a key to the genera, Zootaxa 4510 (1), pp. 1-278 : 238-240

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Siamgryllacris rufa

sp. nov.

Siamgryllacris rufa sp. nov.

Figs. 85 A–I, 86A–K, 100F–G, 101H

Material examined. Holotype (male): Thailand: Tak, Ban Mae Salit, Monkrating resort, elev. 700–800 m (17°30'N, 98°5'E), 11–13.x.1990, leg. S. Ingrisch—(Bonn ZFMK). GoogleMaps

Other specimens studied: Thailand: same data as holotype: 3 males (Bonn ZFMK); Thailand: Chiang Mai, 11 km NE Samoeng , elev. 1100–1200 m (18°52'N, 98°48'E), 10–11.x.1991, leg. S. Ingrisch— 3 females, 2 males (Bonn ZFMK) GoogleMaps ; near Doi Chiang Dao cave , (19°23'N, 98°52'E), 9.x.1991, leg. S. Ingrisch— 1 male (Bonn ZFMK) GoogleMaps ; Phrao district, near Ban Pradu (10 km S of Phrao), (19°15'N, 99°5'E), 28.ix.1985, leg. S. Ingrisch— 2 males (Bonn ZFMK) GoogleMaps ; Nan, Doi Phukha , elev. 1300–1400 m (19°13'N, 101°5'E), 4.x.1991, leg. S. Ingrisch— 1 male (Bonn ZFMK) GoogleMaps ; Umphang , 0–1 km S., (16°2'N, 98°50'E), 15–18.x.1991, leg. S. Ingrisch— 3 females (Bonn ZFMK) GoogleMaps ; Umphang , 0–3 km S., (16°0'N, 98°50'E), 15.x.1991, leg. S. Ingrisch— 1 male (Bonn ZFMK) GoogleMaps .

Diagnosis. The new species is characterized by the pincers-like projections from male tenth abdominal tergite and an apical process from sixth female abdominal sternite; both characters so far unique in Gryllacridinae . Differences to other species are already mentioned under genus. Dialarnaca quadrateprocera Bian, Zhu & Shi, 2017 recently described from Yunnan probably also belongs to Siamgryllacris . S. rufa differs from D. quadrateprocera by the apical lobe of the ninth abdominal tergite being relatively narrower and longer, the ventral margin of the tergite is at ventral end not projecting behind and with the ventral lateral margins strongly oblique. The tenth abdominal tergite has the medial projections larger, more robust and in the direct prolongation of the in middle divided tenth tergite instead of at top of an upcurved stem. The female of S. rufa differs by a distinct projection from sixth abdominal sternite that is missing in D. quadrateprocera , moreover the seventh sternite is distinctly prolonged and the subgenital plate is simply curved between both lateral margins and the apical margin concave and curved while in D. quadrateprocera the lateral margins are sub-angularly bent up and the apical margin is subtruncate.

Description. Medium sized species; some individuals smaller. Head: Face ovoid; forehead nearly smooth with some very fine riffles or impressed dots; fastigium verticis little wider than scapus, separated by a transverse suture from fastigium frontis; ocelli distinct, yellow; subocular furrow indistinct, shallow ( Fig. 85H. Abdominal tergites two and three without stridulatory pegs.

Wings surpassing hind knees ( Figs. 85 A–E). Tegmen: Radius with two branches, both forked near tip; media anterior free from base but in basal area closely approached to radius; cubitus anterior with a single branch at base that divides near end of basal quarter into CuA1 and CuA2; the anterior branch (CuA1) closely approaches MA in a curvature and is connected by a strong cross-vein at the point of closest approach, when it deviates again it divides into MP and CuA1. Variation: in two specimens MP fuses for a short distance, about one cell length, with MA; in one female only on left tegmen MP arises from MA while CuA remains undivided, single branched to tip. Cubitus posterior undivided, free throughout; with 4 anal veins the last two with a common stem.

Legs: Fore coxa with a spine at fore margin; fore and mid femora unarmed; fore and mid tibiae with four pairs of large ventral spines and one pair of smaller ventral spurs; hind femur with 3–11 external and 6–16 internal spines on ventral margins; hind tibia with spaced spines on both dorsal margins, ventral margins with one pre-apical spine; with 3 apical spurs on both sides.

Coloration. General color uniformly brown; vertex, pronotum, tip of abdomen, genicular area of hind femur legs and all tibiae dark purplish red; most spines on femora and tibiae black, the moveable spines on fore and mid tibiae black with white tip. Face yellowish brown with indistinct marbleization; vertex dark brown; compound eyes dark brown. Tegmen semi-transparent yellow, veins little darker; hind wing semi-transparent white; veins and veinlets pale yellow to brown ( Figs. 100 F–G).

Male. Eighth abdominal tergite prolonged. Ninth abdominal tergite globular, down-curved posterior surface with a shallowly depressed groove with a furrow in middle; on top of groove with a small granular conical process over the upper end of the furrow. Tenth abdominal tergite band-shaped, in middle with a pair of posteriorly projecting processes with thickened globular swellings that carry along internal margins a rather wide, compressed, stiffened, black, vertical rim ( Figs. 86 A–E). Epiproct small, largely covered by paraproctes, latter forming large plates mediad of bases of cerci, little overlapping in middle. Subgenital plate little wider than long; lateral margins in roughly basal half with slightly diverging lateral margins, thereafter with converging lateral margins, apical margin substraight, faintly concave; the short (less than half the length of subgenital plate) and thin styli inserted behind the lateral angles ( Fig. 86F). Phallus membranous.

Female. Sixth abdominal sternite with a short conical projection overlapping base of seventh sternite. Seventh sternite with basal margin little excised in middle fitting the process of the sixth sternite, otherwise without striking modification, apex passes into a long membranous zone between seventh sternite and subgenital plate, sometimes building folds. Subgenital plate separated by a prolonged membranous zone from preceding sternite, sclerotised part regularly vaulted with little converging lateral margins; apical margin strongly concave ( Figs. 86 G–K). Base of ovipositor at very base of ventral valves with a small swelling. Ovipositor elongate, in subbasal area little upcurved, afterward straight or substraight, in about apical half with gradually approaching margins; before tip margins more strongly narrowed, tip subobtuse ( Fig. 85I).

Measurements (11 males, 6 females).—body w/wings: male 26–34, female 27–28; body w/o wings: male 23.0–28.5, female 24–27; pronotum: male 3.5–5.2, female 4.5–5.5; tegmen: male 20.0–25.5, female 20–21; tegmen width: male 6.5–6.8, female 6.0–6.5; hind femur: male 11.5–15.5, female 12.5–13.0; antenna: male 90–110, female 90–110; ovipositor: female 16.5–18.0 mm.

Discussion. The short process of the female sixth abdominal sternite often looks as though it is embedded in some transparent secretion. It is probable that this process is clasped by the pincers-like projections of the male tenth abdominal tergite during copulation. The images in Figs. 85–86 show the habitus and the male and female abdominal appendages from a variety of specimens from different locality. There is no distinct variation between the populations. Thus the species can be expected to occur in mountainous areas of the whole Western and Northwestern area of Thailand.

Etymology. The name of the new species refers to the purplish red color pattern on head, pronotum and legs.


Zoologisches Forschungsmuseum Alexander Koenig

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