Perlesta mihucorum Kondratieff & Myers, 2011

Grubbs, Scott A., 2018, An Update On The Stonefly Fauna (Insecta, Plecoptera) Of Maryland, Including New And Emended State Records And An Updated State Checklist, Illiesia 14 (4), pp. 65-80 : 67-70

Perlesta mihucorum Kondratieff & Myers, 2011

was described from upstate New York and has been collected from large streams and small rivers. This is a common species across the panhandle region of western Maryland plus one additional record in the upper Piedmont region .

Remarks. Males of P. mihucorum are readily identified by the combination of paraprocts with subapical tooth mostly anteriorly-directed and not visible in caudal view ( Figs. 8–10 ) and aedeagus with small caecum ca. as long as wide and narrow dorsal patch ( Figs. 11–12 ). Males from Maryland and West Virginia examined in this study were keyed to couplet 12 in Stark (2004), mainly because of the first choice in couplet 10 (“Paraproct spine distinct in lateral aspect”). This is in contrast to Kondratieff & Myers (2011), who illustrated (their Fig. 4 ) and stated “…tooth inconspicuous in lateral view”. This initially led this author to conclude

that the Maryland and West Virginia specimens represented an undescribed species. However, paraproct tooth aspect is herein considered interspecific variability, especially since characteristics of the male caecum, female subgenital plate, and egg align well with the definition of P. mihucorum from New York.

Regarding females, this is the only species of Perlesta with the combination of a subgenital plate with well-developed lobes and deep v-shaped notch ( Fig. 14–15 ) and egg with a smooth chorion and a wide collar that is distinctly stalked, ribbed, and flanged apically ( Figs. 16–18 ). Both males and females have prominent pale yellow median bands on the pronotum ( Figs. 7 , 13 ). The eggs shown with SEM appear inseparable as in Kondratieff & Myers 2011 (their Figs. 9–14 ).

The known disparate ranges of P. mihucorum as reported from New York (Kondratieff & Myers 2011) and herein from Maryland and West Virginia ( Fig. 19 ) are due to incomplete understanding of the distribution of this species. The new state records were unexpected yet not completely surprising considering how little is still known about Perlesta taxonomy and biogeography. Examination of material from the adjacent or intervening states of Delaware, New Jersey, and Pennsylvania should enhance understanding of the distribution of this species. This species is also probably in northern Virginia, more widespread in West Virginia, and likely present in several New England states. Six species of Perlesta in total, including the three females conditionally determined as MD-5, are now known from Maryland. All six species are distributed in the small Appalachian region of western Maryland ( Figs. 19–22 ).

Cultus verticalis (Banks, 1920) is a widespread Appalachian species known from Georgia northeastward to New Hampshire and Quebec ( DeWalt et al. 2018). The females reported here were gravid and eggs of C. verticalis are distinct from C. decisus (Walker, 1852) (Kondratieff 2004) . This state record is not surprising.

Figures

Figs. 7–12. Perlesta mihucorum, male, Maryland, Conococheague Creek; 7, head + pronotum, dorsal profile; 8, paraprocts, lateral view, 250X; 9, paraprocts, dorsal view, 300X; 10, paraprocts, caudal view, 230X; 11, aedeagus, dorsolateral view, 250X; 12, aedeagus, dorsal view, 250X.

Figs. 1–6. Perlesta sp. MD-5, Maryland, Sideling Hill Creek. 1–2, female, head + pronotum, dorsal profile; 3, entire egg, 300X; 4, egg, posterior pole, 500X; 5, egg, posterior pole and collar, 2300X; 6, egg, anterior pole and micropyles, 600X.

Figs. 13–18. Perlesta mihucorum, Maryland, Conococheague Creek; 13, female, head + pronotum, dorsal profile; 14, female, subgenital plate, ventral view, 90X; 15, female, subgenital plate, details of left lobe, ventral view, 400X; 16, entire egg, 270X; 17, egg, posterior pole and collar, 1200X; 18, egg, anterior pole and micropyles, 430X.

Fig. 19. Distribution map of Perlesta mihucorum in eastern North America. The New York localities were plotted using the coordinates provided in Kondratieff & Myers (2011).