Soyedina calcarea, Grubbs, 2006

Grubbs, Scott A., 2006, Soyedina Alexandria And S. Calcarea (Plecoptera: Nemouridae), New Stonefly Species From The Eastern Nearctic Region And Notes On The Life Cycle Of S. Calcarea., Illiesia 2 (6), pp. 39-49 : 43-46

Soyedina calcarea sp. n

(Figs. 32–36)

Material examined. Holotype ♂ and paratype ♀, U.S.A., Kentucky: Hart Co., small spring‐ fed stream, 7.5 km NW Bonnieville, 2–6 March 2000, S. A. Grubbs and J.M. Ferguson (reared) ( INHS) ; Paratypes, same as holotype but 9 March 2000, S. A. Grubbs and J.M. Ferguson, 1♂, 7♀ (reared) ( WKU) ; 2 April 2000, S. A. Grubbs and J.M. Ferguson , 1♂, (reared) ( WKU) ; same but 4‐19 March 2001, S. A. Grubbs and J.M. Ferguson , 11♂, 12♀ (reared) ( WKU, BYU) ; same but 15 February 2003, S. A. Grubbs and J.M. Ferguson , 1♂ ( WKU) ; same but 27 February 2003, S. A. Grubbs , 1♂ ( WKU) ; same but 20 February 2004, J.M. Butler , 1♂ ( WKU) ; Male. Forewing length 7.0–7.5 mm; body length 6.0– 6.5 mm. Body color, wings, absence of gills, cerci, hypoproct, and epiproct (Fig. 32) as in S. vallicularia . Paraproct with two lobes; inner lobes small, narrow, and lightly sclerotized; outer lobes enlarged, darkly sclerotized and robust, broadest at base, narrowed noticeably at distal third, both inner and outer portions concave; apical portion constricted toward concave tip, inner and outer shoulders rounded, with outer shoulder raised slightly above inner shoulder (Figs. 33–35).

Female. Forewing length 7.5–9.0 mm; body length 6.0–8.0 mm. Body, leg, and wing coloration similar to male. Subgenital plate well‐ developed; base broad, extending from posterior of seventh sternum entirely over eighth sternum and approximately ¼ over ninth sternum; apical portion darker than basal portion and ending in broadly‐ round tip (Fig. 36).

Diagnosis. Soyedina calcarea is differentiated from both S. alexandria and S. vallicularia by the shape of the outer paraproctal lobe. The compact, robust paraproct with the concave tip of S. calcarea is easily distinguished from the narrow, flask‐ like paraproct of S. vallicularia . The combination of the concave tip and the noticeably concave inner and outer margins of the paraproct of S. calcarea are also readily distinguished from S. alexandria . With S. alexandria the paraproct lobe is only faintly concave along both the inner and outer margins and the tip is straight or slightly convex. In addition, the epiproct and female subgenital plate of S. calcarea cannot be distinguished from S. alexandria and S. vallicularia .

Remarks. The highly asymmetrical and scaly epiproct, with the distinctive inner structure, is shared only by S. alexandria , S. calcarea , and S. vallicularia , and easily separates these three species from the remaining eastern Nearctic Soyedina species ( S. carolinensis , S. kondratieffi , S. merritti and S. washingtoni ). The latter four species are distributed mainly in the Appalachian Mountains. Soyedina vallicularia is distributed broadly, as (1) throughout the northern Great Lakes region east to Maine and Nova Scotia, (2) at lower elevations in the Appalachian Mountains, and (3) within the lower Ohio River Basin and one location in the lower Cumberland River Basin in Tennessee ( Grubbs 1997; Stark & Baumann 2005), and (4) Heimdal et al. (2004) provided the first record west of the Mississippi River in eastern Iowa. The type and sole known locality of S. calcarea occurs within the southwestern portion of the distribution of S. vallicularia , while the known localities of S. alexandria overlap with S. vallicularia only in central Tennessee.

Etymology. The specific epithet is in reference to the well‐ developed calcareous limestone bedrock in the central Kentucky karst region.

Biology. The Kentucky type locality (195 m A.S.L.) emanates on a sandstone ridge and flows 35 m as an intermittent reach before dropping over a hollowed cliff. The stream continues intermittently before two small springs provide perennial surface flow for approximately 20 m. Downstream of the spring reach the stream sinks through fractured limestone into a subterranean fluvial network. Soyedina calcarea adults have been collected only from the spring reach. Other stonefly species collected with S. calcarea from the type locality were Allocapnia recta (Claassen) , Amphinemura varshava (Ricker) , Clioperla clio (Newman) , Diploperla robusta Stark and Gaufin , Leuctra alta James , L. sibleyi Claassen , L. cf. tenuis (Pictet) , and Ostrocerca truncata (Claassen) .

The adult flight period of S. calcarea at the Kentucky type locality occurred between mid‐ February and early April. Early‐ instar nymphs appeared by May after no apparent egg diapause and grew continuously through summer and autumn ( Fig. 37 ). Nymphal growth increased through winter prior to emergence. The growth pattern displayed was similar to the univoltine‐ slow cycles ( Hynes 1961) displayed by S. vallicularia in Ontario ( Harper 1973) and Quebec ( Mackay 1969). Both studies revealed that early‐ instar nymphs appeared shortly after adult emergence, suggesting a direct development of eggs similar to S. calcarea . The similar growth patterns displayed by the two species, despite the disparate latitudinal settings, are not surprising because the two taxa are likely sibling species.

Figures

Fig. 37. Size frequency histograms of head capsule width for Soyedina calcarea from the Kentucky type locality. A: May 2002 – April 2003; B: May 2003 – April 2004. Numbers on top give number of specimens per month; n = 2300 nymphs total across the two‐year sampling period. Vertical arrows refer to adult flight period.