Nixe dorothae Webb & McCafferty, 2011

Webb, J. M. & Mccafferty, W. P., 2011, Contributions to the larvae of North American Nixe (Ephemeroptera: Heptageniidae), with the description of N. dorothae sp. nov. from southern Indiana, Zootaxa 3065 (1), pp. 27-37 : 27-32

Nixe dorothae Webb & McCafferty NEW SPECIES

Larvae: Body length 7.5–10.5 mm; caudal filaments 5–8.5 mm. General color brown with pale markings ( Figs. 1– 3). Head: Head capsule brown with two pale markings on anterior margin separated by distance less than distance between antennae bases, with pair of pale markings directly posterior to marginal pale markings, with small black spots often present near anterior margin, and with narrow pale streak extending from compound eye to lateral margin of head capsule; ocelli black with pale spot anterior to median ocellus and pale spot laterad of lateral ocellus. Mouthparts: Labrum ( Fig 5a ) ventrally with single row of 6–11 stout setae on either side of midline, anterolaterally with two rows of long, robust setae. Mandibles with 4–5 setae at base of incisors. Maxillae ( Fig. 5b ) with 11–14 comb setae of 5–7 spines on anterior margin, lateral two comb setae more hairlike, and numerous scattered fimbriate setae on ventral surface of galealacinia; maxillary palp with 1–3 fine setae on base, first segment with sparse long fine setae on anterior margin and several somewhat robust setae on posterior margin. Thorax: Brown with pale markings. Forefemur cream or pale brown with pair of brown chevron shaped markings, with dorsal row of long setae, with ventral row of sharp robust setae and with numerous pointed robust setae on anterior surface (as in Fig. 6b ); foretibia pale brown with diffuse brown median band, with row of short fine setae on posterior margin and row of short fine setae on lateral ridge, and with 7–9 pointed robust setae on inner surface; foretarsus pale brown with distinct brown band basally, with long fine setae on posterior margin and scattered fine setae; foretarsal claw with two rows of denticles. Midleg similar to hindleg but with less numerous setae and no robust setae on lateral ridge of tibia. Hindfemur ( Fig. 6a ) similar to forefemur but setae more numerous; hindtibia with row of medium fine setae and 4–5 pointed robust setae on posterior margin, with 7–8 pointed robust setae and scattered fine setae on lateral ridge, with 11–12 robust setae on anterior margin, and with 12–20 robust simple setae on inner surface; hindtarsus with long fine setae on posterior margin and scattered fine setae, and with 6 simple pointed robust setae on inner surface; hindtarsal claw with two rows of denticles ( Fig. 6c ). Abdomen: Terga 2–7 brown with pair of submedian pale marks, single faint posteromedian pale mark, two pairs of sublateral pale marks (less evident in male larvae: Fig 3 ), and pair of lateral pale marks ( Figs. 1–3). Sterna ( Fig. 4 ) cream to pale brown with reddish brown pair of sublateral markings (more distinct on distal segments); anterior margins of distal segments often reddish-brown. Posterolateral spines present on segments 2 or 3–8. Gills cream, present on segments 1–7, with variously developed fibrils present on gills 1–6. Caudal filaments pale brown with spines at articulations and numerous fine intersegmental setae.

Adult Male (in alcohol): Length: Forewing 5.0–6.0 mm; body 5.0–6.0 mm. Compund eyes grayish green to black, contiguous dorsally. Ocelli black basally, grayish green apically. Frons orange-yellow. Notum uniformly creamy orange; sternum yellow. Legs cream; forefemur apically orange-brown. Wings translucent. Abdominal terga (Figs. 7,8) reddish brown with pale median stripe, submedian pale marks, antero- and posterolateral corners pale, and posterior margins brown. Abdominal sterna cream. Caudal filaments cream, basal articulations reddish brown. Genitalia cream, penes ( Figs. 9 , 10) ventrally with pair of discal spines; basal sclerites with 1 or 2 pairs of minute dorsolateral spines; lateral sclerites without spines; apical sclerites slightly recurved, with 1 or 2 pairs median spines. Subgenital plate slightly emarginate with small moderately pointed lateral projections ( Fig. 9 ) and with sparse minute spines.

Adult Female (in alcohol): Length: Forewing 6.5–7.0 mm; Body 6.0–7.0 mm. Eyes gray-green to black. Ocelli black basally, gray-green apically. Frons orange. Notum yellow-orange; sternum yellow. Legs cream. Wings translucent. Abdomen yellow-orange; posterior margins of terga reddish brown; faint traces of reddish brown marks laterally; ninth sternum truncate. Caudal filaments cream.

Etymology. This species is named in honor of the JMW's late grandmother, Dorothy Webb.

Diagnosis and discussion. Larvae of N. dorothae are identified by the presence of two rows of denticles on the tarsal claws ( Fig. 6c ). Nixe dorothae and N. perfida are superficially similar and occur in the same geographic region, but, in addition to the second row of denticles, N. dorothae larvae usually have two pairs of pale sublateral spots on each abdominal tergum ( Fig. 1) whereas N. perfida larvae have only a single pair. Nixe flowersi is also known from southern Indiana but differs from N. dorothae by having a single row of denticles on the tarsal claws, clavate robust setae on the femora (similar to Fig. 18 ), and much more extensive pale areas on the abdominal terga ( Fig. 19 , McCafferty 1977: Fig. 3 , as Heptagenia perisimplex McDunnough, 1929 ) The reddish brown markings on the abdominal sterna can vary within populations from completely absent to well developed and should not be considered diagnostic.

Adult males are differentiated from North American congeners by the combination of the reddish brown dorsal color pattern ( Fig. 7 ) and penes with median spines on the apical sclerites ( Fig. 10). The only other North American species with spines on the apical sclerites is N. flowersi , but its abdomen is cream colored rather than reddish brown. Nixe horrida , N. lucidipennis , N. perfida and N. rusticalis all have reddish brown abdominal terga, but the penes lack median spines on the apical sclerites. Nixe dorothae were most often collected from small, intermittent or spring-fed streams in southern Indiana.

Material examined. HOLOTYPE: IN: JACKSON CO: ♀ larva, Hoosier Nat For, Combs Br at road, near Maumee, 39°01'N 86°17'W, 12-V-2005, JM Webb & JM Hwang . PARATYPES: IN: JACKSON CO: 2 ♂ imagos (genitalia slide mounted in Euparal and Cellosolve), same data as holotype ; 21 larvae, same data as holotype ; 11 larvae (1 slidemounted), Hoosier Nat For, Little Salt Cr at Co Rd 1075N, 39°01'53”N 86°10'20”W, 5-V-2005, LM & MW Jacobus. All material deposited in Purdue Entomological Research Collection, West Lafayette, IN .

Other material examined: IN: BROWN CO : 18 larvae, stream feeding Yellowwood L, Yellowwood St For , V-24-1978, M Minno & D Bloodgood; JACKSON CO : 4 ♂ imagos (genitalia of 1 slide mounted), 4 ♂ subimagos, 6 ♀ imagos with associated exuviae, same data as holotype ; 10 larvae, same data as holotype ; 47 larvae (1 slidemounted), Hoosier Nat For , Combs Br at road, near Maumee, 39°01'N 86°17'W, 5-V-2005, LM & MW Jacobus ; 3 larvae (1 slidemounted), trib Buck Cr , NE Spraytown, 39°01'36”N 86°05'33”W, 7-V-2000, LM Jacobus ; 7 larvae, Hoosier Nat For , Cross Br at Co Rd 650W, 39°02'55”N 86°09'53”W, 5-V-2005, LM & MW Jacobus; SPENCER CO : 2 larvae, ditch 1 mi W Lincoln St Prk , at gravel road and RR track, 7-V-1972, WP McCafferty & AV Provonsha ; 4 larvae, ditch 1 mi W Lincoln St Prk , at gravel road and RR track, 7-V-1972, JW Smith ; 5 larvae, trib E Fk Little Pigeon Cr 2.5 mi S Lincoln on gravel road, 6-V-1972, D Lockwood ; 30 larvae, trib of Little Pigeon Cr 2 mi SW Lincoln St Prk on gravel road, 17-V-1973, WP McCafferty, K Black, AV Provonsha ; 6 larvae, N Frk Little Pigeon Cr at Hwy 68, 6-V-1972, JW Smith ; 10 larvae, E Frk Little Pigeon Cr 2 mi S Lincoln St Prk on gravel road, 7-V-1972, no collector indicated ; 1 larva, Crooked Cr 1 mi S Lamar, E of St Hwy 245, 17-V-1973, WP McCafferty, K Black, AV Provonsha ; 6 larvae, small trib of Little Pigeon Cr 1.5 mi S Lincoln on gravel road and RR tracks, 13- V-1976, AV Provonsha, M Minno; WARRICK CO : 5 larvae, Pokeberry Cr , 7-V-1972, L Lehman ; 5 larvae, Wallace Fk Little Pigeon Cr , 6-V-1972, JW Smith ; 3 larvae, Wallace Fk Little Pigeon Cr , 7-V-1972, D Lockwood ; 4 larvae, Wallace Fk Little Pigeon Cr , 7-V-1972, L Lehman .

Figures

FIGURE 5. Nixe dorothae sp. nov. mouthparts: a, ventral view of labrum; b, ventral view of maxilla.

FIGURE 6. Nixe dorothae sp. nov. hindleg: a, general view; b, robust setae on anterior surface of femur; c, tarsal claw.

FIGURES 2–4. Nixe dorothae sp. nov.: 2, dorsal habitus of female larva; 3, dorsal habitus of male larva; 4, ventral habitus of male larva.

FIGURES 7–9. Nixe dorothae sp. nov.:7, dorsal habitus of male (genitalia removed, visible foreleg stunted); 8, lateral habitus of male (genitalia removed, visible foreleg stunted); 9, dorsal view of genitalia.

FIGURES 14–18. Nixe rusticalis: 14, labrum, apical view; 15, maxilla; 16, hindleg; 17, foretarsal claw; 18, robust seta from forefemur.

FIGURES 19–24. 19, Nixe flowersi dorsal habitus (topotype); 20, Nixe lucidipennis dorsal habitus; 21, Nixe inconspicua; 22, Nixe spB; 23, Ecdyonurus simplicioides dorsal habitus; 24, Ecdyonurus simplicioides head capsule.