Xanthoneuria Uchida, 2011

Uchida, Shigekazu, Stark, Bill P. & Sivec, Ignac, 2011, Xanthoneuria, A New Genus Of Stonefly (Plecoptera: Perlidae) From Japan, Illiesia 7 (5), pp. 65-69 : 65-68

Xanthoneuria Uchida , gen. nov.

( Figs. 1-14 )

Type species: Acroneuria fulva Klapálek, 1907

Species list and known distribution:

Xanthoneuria bolivari ( Klapálek, 1907) , comb. nov. - Honshu

X. fulva ( Klapálek, 1907) , comb. nov. – Hokkaido, Honshu

X. jouklii ( Klapálek, 1907) , comb. nov. – Honshu X. unimaculata ( Zhiltzova, 1981) – Korea, Russian Far East

Male genitalia. Abdominal terga 1-8 unmodified; tergum 9 with a posteromedian pair of dark sclerites and tergum 10 bearing a darkened, fused epiproct sclerite ( Fig. 1 ). Paraprocts with a short pointed hook ( Fig. 4 ). Sternum 9 with a transversely elongate, ellipsoidal hammer ( Figs. 2-3 ); membranes adjacent to hammer hairy, convex anteriorly and concave posteriorly. Penis membranous, without sclerites and consisting of five telescoped sections variously armed with fine spinules and hairs ( Figs. 5-8 ). Basal section bearing a ventral band of slender spinules; second section short and covered by fine, short spinules and sparse hairs ventrally and laterally; third section bearing lateral patches of short spinules; fourth section very short with dense band of short spinules laterally and ventrally and apical section with sparse covering of fine slender spinules, a pair of dorsobasal swellings and a pair of dorsal projections adjacent to gonopore.

Female genitalia. Sternum 8 with a round convex subgenital plate delimited anteriorly by a narrow membranous fold ( Figs. 9-11 ). Posterior margin with a small mesal notch; margin bearing minute hairs; dorsal membrane of plate bearing a transverse sclerite. Vagina membranous, without sclerites but bearing fine internal spinules ( Fig. 13 ). Spermatheca larger than vagina, with thick stalk and 5-12 accessory glands.

Egg. Oval, or with one or two large lateral depressions. Anchor large, bowl shaped, without pedicel and covering basal half of egg ( Fig. 12 ). Distal third of anchor thickened, forming a wide circular band. Collar absent. Chorion with minute punctures and shallow hexagonal follicle cell impressions. Micropylar canals straight.

Mature larva. Body length 17-37 mm. General color pale yellow marked with dark brown in fresh specimens, bleaching to white in alcohol. Occipital spinule row irregularly spaced. Anterior strip of proventriculus flat, completely armed with golden spines except bare posterior end ( Fig. 14 ). Strip on superior fold was as wide as, or slightly wider than, that on inferior fold. Accessory patch of spines often present between major anterior strips. Posterior spinule patch ca. two-fifths as long as anterior patch.

Diagnosis. Xanthoneuria is allied to the Calineuria-Doroneuria-Hesperoperla group of tribe Acroneuriini by virtue of the shared epiproct sclerite and irregularly spaced larval occipital spinule row. Penial armature in Calineuria and Hesperoperla consists of much heavier concentrations of thicker and longer spines ( Stark & Gaufin 1974; Baumann & Stark 1980) than is present in the new genus, and that of Doroneuria is fundamentally different with the presence of a large dorsal sclerite ( Stark & Gaufin 1974). Eggs of Xanthoneuria lack a collar which distinguishes them from eggs of Calineuria and Hesperoperla ( Stark & Gaufin 1976) ; the eggs are generally similar to those of Doroneuria ( Stark & Gaufin 1976) but the females of that genus lack a developed subgenital plate. Larvae of the new genus are distinct from related genera by several characters, most notably in the presence of pale pigment over most of the abdominal terga.

Figures

Figs. 1-8. Male genitalic structures of Xanthoneuria fulva. 1. Terga 9-10. 2. Sternum 9, lateral aspect. 3. Sternum 9, ventral aspect. 4. Right paraproct, anteromedian aspect. 5. Everted penis, lateral aspect. 6. Everted penis, ventral aspect. 7. Everted penis, dorsal aspect. 8. Contracted penis, dorsal aspect.

Figs. 9-13. Female genitalic structures and egg of Xanthoneuria fulva. 9. Subgenital plate, ventral aspect. 10. Subgenital plate margin, dorsal aspect. 11. Subgenital plate, lateral aspect. 12. Egg. 13. Vagina and sterna 8-9 (scale 0.05 mm for setal detail insets).

Fig. 14. Larval proventriculus for Xanthoneuria fulva (A) and X. jouklii (B) (scale 0.05 mm for details of armature, 1.0 mm for others).