Isogenoides varians (Walsh)

Ray, Donald H., Abad, Rick L., Rasmussen, Andrew K. & Stark, Bill P., 2012, New Records And An Updated Checklist Of The Stoneflies (Plecoptera) From Florida, Illiesia 8 (1), pp. 1-9 : 3-4

Isogenoides varians (Walsh)

Distribution. This species was previously known from Illinois, Indiana, Mississippi, North Carolina, South Carolina, Tennessee and Virginia (Stark & Stewart 2002; Sandberg 2005; Stark et al. 2009) but doubtful from Kansas, Michigan and Minnesota ( Sandberg 2005). Our records from the Perdido River, which forms the boundary between Alabama and Florida ( Fig. 2 ), are the first reports Isogenoides varians from these two states.

Material examined. FLORIDA: Escambia Co., Perdido River Barrineau Bridge off CR 97, N 30°41’25”, W 87 °26’25”, 14 December 2010, D. Ray, R. Abad , 4 larvae, (1♀ penultimate instar exuviae molted on 2 February with exuviae reared 23 March 2011). Same site, 8 January 2011, D. Ray, R. Abad , 9 larvae (4♂ & 2♀ with exuviae reared 17 February-9 April). Same site, January 2011, D. Ray, R. Abad, B. Albrecht 9 larvae (2♂ & 2♀ penultimate instar ♀ exuviae molted on 5 February & ♂ exuviae molted on 7 February with exuviae reared ♀ 28 February - ♂ 9 April). Same site, 23 March 2011, D. Ray, R. Abad, M. King, 1 larva (♀ with exuviae reared 28 March).

Remarks. The collection site is on the middle reach of the Perdido River that forms the border between Florida and Baldwin County, Alabama. Isogenoides varians had not been recorded from Alabama ( Grubbs 2011). Isogenoides larvae were collected in December 2010 through March 2011 and emerged beginning February 2011 through March 2011. Reared specimens were fed larval chironomids, simuliids, tipulids and mayflies from the collection site. The substrate where the I. varians larvae were collected consisted of gravel in riffles and high velocity (0.5-1.1 m /s) in the thalweg. Isogenoides varians larvae were not found in the slower reaches containing sand and fine silt deposits. The riparian forest at the collection site is an Atlantic whitecedar ( Chamaecyparis thyoides (Linnaeus) Britton , et al.) community. Other stoneflies collected at this site include Acroneuria sp. , Hydroperla phormidia Ray & Stark , Helopicus bogaloosa Stark & Ray , Isoperla sp B , Neoperla sp. , Nemocapnia carolina Banks , Paragnetina fumosa (Banks) , Perlinella drymo (Newman) , Pteronarcys dorsata (Say) , and Taeniopteryx lonicera / lita . Hydroperla phormidia had also not previously been recorded from Alabama ( Grubbs 2011).

Figures

Fig. 2. Distribution of Isogenoides varians in Florida.