Agnetina extrema ( Navás, 1912 )

Teslenko, Valentina A., 2024, Eggs of Perlidae (Insecta, Plecoptera) of the Russian Far East, Zootaxa 5551 (1), pp. 91-115 : 102-105

Agnetina extrema ( Navás, 1912)

Figs. 45‒50

Material examined. Russia, Far East, Amurskaya Oblast: 7♂, 1♀, Bolshie Simichi River , Bureya River basin, Amur River basin, 4.07.2014, coll. V. Teslenko; 2♀, Bolshaya Maccha River, Amur River basin, 3.07.2013, coll. V. Teslenko; Jewish Autonomous Oblast: 2♂, 1♀, Bira River, about 4 km below the Zhelty Yar village , 31.07.− 3.08.2003, coll. T. Tiunova; 1♀, Bastak Nature Reserve, Maly Sorennak River , Amur River basin, 18.07.2022, coll. T. Vshivkova; Khabarovsk Krai: 7♂, 2♀, Sel’gon River, railway bridge, Amur River basin, 29.06.2010, coll. I. Tiunov; 1♂, Pokha River, Bol’shaya Khurba River basin, Amur River basin, 11.07. 2010, coll. N. Yavorskaya; 7♂, 2♀, Khoidur River , 18.08.1997, coll. T. Tiunova; 1♀, Levaya Silinka River, Amur River basin, 29.07.2006, coll. E. Makarchenko.

Egg. Oval ( Fig. 45 ), length 337–374 µm and width at the equator 280–283 µm (n=2); the posterior pole is wider than the anterior pole; the anterior pole is narrow and rounded ( Figs. 45‒46 ). Collar nipple-shaped and set on a thin subapical plate; the additional thin rim around the collar base is weakly expressed ( Fig. 48 ). Anchor plate is umbrella-shaped ( Figs. 45, 47 ), wide, and covers a subapical ring; the anchor surface is studded with mushroom bodies distributed irregularly and densely towards the peripheral edge; the center of the anchor plate is devoid of bodies ( Figs. 45, 47 ). Chorion surface is covered throughout with hexagonal FCIs with shallow pits ( Figs. 45−46, 49−50 ). The area between the micropylar line and the anterior pole is almost smooth with hexagonal FCIs but without punctuation, occupying about 1/5 of the egg length ( Figs. 46, 49 ). The micropylar line is located close to the anterior pole; the sperm guides are tunnel-shaped and located obliquely to the chorion axis; the orifices without rims ( Figs. 49‒50 ) are surrounded by FCI rosettes resembling flowers ( Figs. 46, 49‒50 ).

Comments. The egg of A. extrema was first briefly described by Sivec et al. (2005), including size and shape. Our supplementary description partly agrees with the original description of these features. According to our data, the egg length of A. extrema is shorter than previously noted and shorter than the egg length of A. brevipennis . The eggs of both species differ not only in size but also in shape: in A. brevipennis , the egg is oval-elongated; the anterior pole is widely rounded, while in A. extrema , the anterior pole is noticeably narrowed. In A. extrema , the smooth region with hexagonal FCIs without punctuation between the micropylar line and the anterior pole occupies about 1/5 of the egg length, while in A. brevipennis , the smooth region occupies about one-third of the egg length.

Distribution. East Palaearctic, mainland, widespread from Siberia (Krasnoyarsky Krai, Transbaikalia) to the Russian Far East (south Yakutia, Amurskaya Oblast, Jewish Autonomous Oblast, Khabarovsk Krai, Primorsky Krai). Mongolia.

Figures

FIGURES 45–50. Agnetina extrema (Navás, 1912). Russia, Far East, Amurskaya Oblast, Bolshie Simichi River, Bureya River basin, Amur River basin. Egg, cleaned. 45. Habitus, with anchor, lateral. 46. Habitus, collar, subapical plate, chorion structure, micropylar row, lateral. 47. Anchor plate with band of globular bodies along edge, dorsolateral. 48. Collar nipple-shaped with a thin subapical plate, dorsolateral. 49. Anterior pole, chorion structure, micropylar row, orifices surrounded by rosettes, lateral. 50. Micropyle, the chorion structure, orifice, and the sperm guide, lateral.