apical angle

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ap·i·cal an·gle

the angle between two plane surfaces of a prism.
References in periodicals archive ?
fruticicola, especially by its (slightly less) close-set teleoconch ribs, but this species has a smaller, less elongate shell with less rapidly expanding whorls, less sharp apical angle and spire angle, proportionally larger body whorl, and differs in protoconch sculpture.
The two species differ in teleoconch rib spacing, coiling tightness, width of the apical whorls, apical angle, proportional aperture and body whorl size, and whorl convexity.
Small, cylindrical shell of 5 to 6 whorls; protoconch smooth, depressed; ultimate whorl three times length of spire, tapering convexly to base; whorls gradate, sharply shouldered with flat to slightly inclined ramps; surface smooth; apical angle of 80 degrees.
Marginal impression distinct, narrow near apical angle, broadly widened to the basal angles, ending in fairly deep dimple-like, basal impression which is situated near hind margin.
Area between lateral carinae of pronotum dark brown; two branches of outer apical angle of genital styles subequal; aedeagus with one small spine situated near basal third, directed caudally M.
Forewings broadening apically, cross veins located in apical half, with apical angle acute, outer margin approximately straight, oblique, posterior margin sinuate, with irregular markings at apical half (Figs.
3), the pronotum is yellow with an irregular black spot on each callosity, the clavus is black except inner and claval commissure mostly yellow, and corium black with costal margin, apical angle, narrow apical margin and base and apex of cubital vein yellow.
Dorsal coloration: Head yellowish hazel except for 2 short reddish brown irregular transverse marks restricted to the interocellar space; antennal segments I to IV reddish brown; pronotum yellowish orange with 2 large, irregular pale to dark brown spots at posterior lobe and transverse line; scutellum reddish brown to dark brown, middle third of apical half yellowish orange; clavus dark brown, claval commissure yellow; corium dark brown, costal margin and apical angle yellow; hemelytral membrane ocher, and apical margin widely hyaline.
This genus is closely related to Neobelocera Ding and Yang, 1986 (Chen & Liang 2005), which also feeds on bamboo, but differs in the following: the latter with the antennae markedly flattened, first segment subsagittate, a longitudinal carina down middle, with the apex unequally bifurcate, the inner apical angle much longer than outer apical angle, the postclypeus in profile, apical part of median carina bend at rounded, not angled, the rostrum very short, only reaching mesotrochanters, and the forewing often with snatchy blackish brown markings, in dark portion veins bear white spots.
5 cm in length with apical angles ranging from approximately 35-40 [degrees].