Phanoperla wedda Zwick, 1982

Mason, Denise & Stark, Bill P., 2015, Notes On The Genus Phanoperla Banks From Sri Lanka And India (Plecoptera: Perlidae), Illiesia 11 (4), pp. 29-40 : 37

Phanoperla wedda Zwick

( Figs. 22-27 )

Phanoperla wedda Zwick 1982a:118 .

Holotype ♂ (United States National Museum), Hasalaka Oya, Kandy District, Ceylon [Sri Lanka]

Material examined. SRI LANKA: Matale District , Kibissa, 0.5 miles W of Sigiriya Jungle, 28 June-4 July 1978, K. V . Krombein, 7♂, 7♀ ( USNM). Ratnapura District , Balihyloya, 9-10 April 1978, M.D. Hubbard, T . Wijesinhe, 1♀ ( USNM). Uggalkaltota , 23-26 June 1978, K. V . Krombein, P.B. Karunaratne, T . Wijesinhe, L. Jayawickrema, N. Karanaratne, 29♂, 15♀ ( USNM) .

Egg. Spindle shaped. Length ca. 364-381 μm, equatorial width ca. 270-280 μm ( Fig. 22 ). Collar ca. 25-29 μm long and ca. 102-114 μm wide, margin slightly flanged and irregularly incised ( Figs. 23-24 μm), sides bearing a series of thick vertical ridges (ca. 10 in lateral aspect); ridges continue onto body of egg for ca. 142 μm, forming a series of narrow striae, subtended on each side by a row of punctations; broad sulci between striae without punctations ( Figs. 22-23, 26 ). Mesal chorionic zone (ca. 178 μm wide) consists of rather widely spaced coarse pits which extend over micropylar row and become somewhat finer beyond micropyles ( Fig. 25 ). Lid covered with follicle cell impressions, most containing five pits. Micropylar orifices circular, without prominent sperm guides ( Fig. 27 ).

Comments. The scanning electron micrographs provide a few subtle chorionic details not observed in Zwick’s (1982a) description. These include, 1) the extension of chorionic striae (or “ribs”) onto the collar ( Fig. 8 ), 2) the presence of FCIs on the lid, and 3) continuation of the fine punctations to the base of lid (not shown in Zwick’s Fig. 24c , but noted in his description as “…punctures, very fine along otherwise invisible suture of lid;…”). Although the egg appears distinctive among the Sri Lankan species, several species (e.g. P. huang Sivec & Stark 2010b ; P. magnaspina Sivec & Stark 2011 ; P. uchida Sivec & Stark 2010b ) from other areas have eggs with a mixture of similar chorionic striae and punctations ( Sivec & Stark 2010b; 2011). The common occurrence of this egg pattern in other species groups raises the question of whether the two named species in the testacea -group with unknown females ( P. ceylonica , P. srilanka ) might have eggs similar enough to those of P. wedda (also included in this group) to go undetected. We have examined at least one egg from every female listed above with light microscopy and have examined several eggs (ca. 10) from each of 10 females with SEM. No significant variation of the chorionic pattern has been detected but additional samples are needed from more localities to test this hypothesis.

The following key is modified from that of Zwick (1982a) but includes only males of species known from India and Sri Lanka. The Sri Lankan Plecopteran fauna is completely endemic, consequently the initial couplet is based on geographic separation.

Figures

Figs. 22-27. Phanoperla wedda egg. 22. Lateral aspect. 23. Collar end (s = stria). 24. Anchor and collar (at = anchor tentacle). 25. Lid and micropylar zone. 26. Anchor and collar, apical aspect. 27. Micropyles (m = micropyle).

Figs. 7-12. Putative Phanoperla nana egg. 7. Lateral aspect. 8. Collar end. 9. Chorionic detail surrounding collar. 10. Lid and micropylar zone. 11. Collar and anchor. 12. Micropyles.