Epeorus melli ( Ulmer, 1925 ) Zhou & Wang & Xie, 2007

Zhou, Chang-Fa, Wang, Shi-Lei & Xie, Hui, 2007, The Nymph and Additional Imaginal Description of Epeorus melli new combination from China (Ephemeroptera: Heptageniidae), Zootaxa 1652 (1), pp. 49-55 : 49-53

Epeorus melli ( Ulmer, 1925) n. comb.

( Figs. 1–29 )

Thalerosphyrus melli Ulmer, 1925: 101 , figs. 89–93. Types: male, female, collected in Luofushan Mt. ( Lofaushan ), Maizi Mt. (Mahn tsi shan), Guangdong (Kuangtung) province, southern China.

Thalerosphyrus melli — Wu, 1935:252; Ulmer, 1935 –1936:215; Gui, 1985:86; You et Gui, 1995:45, fig. 41 (male).

Material examined. CHINA: Guizhou province: Rong-Jiang Ct., Dan-Jiang village (10820’394’’E, 2620’550’’N, alt. 685 m),, Lei-Gong-Shan reserve, 1 10 35 Larvae (L), 2005-IX-15-18; Leishan Ct., Fang- Xiang village (10816’ 551’’E, 2626’599’’N, alt. 880 m), Lei-Gong-Shan reserve, 11 L, 2005-IX-13-15, col- lected by Peng LI & Zhijie WANG ; Fujian province, Sang-Gang village, Wuyi Mt. , 6, 1995-VII-15, Ling YIN & Changfa ZHOU ; Jiu-qu stream, Wuyi Mt. , 31, 1980-VII-23, collected by Dashou YOU ; Zhejiang province, Qingyuan Ct., Zhouqi village , 130, 1994-VIII-9, Chaodong ZHU & Changfa ZHOU ; Anhui province, Huoshan Ct., Qiling village , 1, 1983-VII-31, Xinyong WU ; Hubei province, Dabie Mt. , 203, 2000-VIII-20, Xiulan RONG .

Nymph:body length 15.0–16.0 mm, caudal filaments 19.0–21.0 mm. Head capsule gray dorsally, with 4 pale dots near anterior margin; anterior margin evenly convex, with row of dense setae; posterior margin straight or slightly concave, with submedian tufts of setae ( Figs. 1 , 25, 26 ); ocelli pale, basal portion dark. Labrum 0.25 as wide as head capsule, with shallow U-shaped median emargination, a cluster of thick submarginal setae lateral to median emargination on dorsal surface; long hair on anterolateral margin ( Fig. 2 ). Mandibles with tuft of bristles on inner margin ( Figs. 3, 4 ); outer incisor much longer and heavier than inner incisor, margins serrated; ventral margin of inner incisor serrated; each incisor with a row of bristles on ventral margins; prostheca represented by 2 fine setae ( Fig. 5 ). Maxillae with armature on crown of galea-lacinia absent, apex terminating in triad of stout spines; ventral surface with submedian row of setae and mesal margin with a row of dense setae, basal setae longer than others; maxillary palpi 2-segmented, basal segment expanded basally; apical segment about 1.2 X length of basal segment, apex acute, with brush composed of small dense pectinate spines; a row of sparse setae along brush basally ( Fig. 6 ). Hypopharynx with lingua rounded at apex, superlinguae slightly expanded laterally, with dense row of setae at apex ( Fig. 7 ). Labium with small V-shaped separation between glossae, paraglossae moderately expanded laterally, glossae and paraglossae with dense setae dorsally; apical segment of palpi subequal in length to basal segment, with dorsal transverse row of spines near apex and a row of pectinate spines ventrally ( Fig. 8 ).

Pro- and mesonota gray to brown, with pale dots and stripes dorsally. Femora of all legs gray, with irregular 9 brown to dark dots on dorsal surface, 3 basal dots smaller, one of them and a median one obviously darker than others, the median darker dot larger than basal one, very clear; femora with row of long setae on outer margin, those setae further have fine setae, form a pectinate structure; femora surface with scattered irregularly, mostly spatulate spines ( Fig. 12 ). Foretibiae slightly longer than forefemora, mid tibiae subequal to mid femora, while hind tibiae slightly shorter than hind femora; tibiae with basal and median brown to dark brown rings. Tarsi dark brown, all tibiae and tarsi with row of setae on dorsal margins ( Figs. 9, 10, 11 , 25, 26 ). Claws with 4 subapical denticles ( Fig. 13 ).

Abdomen with median row of setae dorsally on terga, each tergum with 2 pale dots and a row of obvious spines along posterior margin, 1–2 setae located between two neighbor spines; posterolateral spines of terga elongated into 2 projections ( Figs. 14, 15 , 25, 26 ). Gills on abdominal segments 1–7, with lamellae and fibrilliform portions but fibrilliform threads of gills 7 reduced, lamellae with distinct tracheae; lamellae of gills 1 expanded anteriorly but not meeting ventrally, anterior margin with setae, additional small tuft of setae located medially ( Fig. 16 , 26 ); gills 2–6 similar in shape but progressively smaller posteriorly; anterior margin sclerotized and with dense short setae ( Fig. 17 ). Gills 7 similar to gills 2–6 but smaller with indistinct fold line ( Fig. 18 ). The hind margin of all gills thickened progressively from anterior to posterior, those of gills 7 clear, like a sclerotized rib ( Fig. 18 ). Cerci: dorsal setae on several basal segments, articulations with very tiny spines; terminal filament rudimentary ( Figs. 1 , 15, 19 , 25, 26 ).

Male: forewings with well red to brown pigmented cross veins of C and Sc section, stigmatic region semi-hyaline, several apical cross veins in R 1 section pigmented ( Fig. 20 ). Hind wings hyaline ( Fig. 21 ). Genitalia: long basal segment of forceps broader at apex than at base. Dorsal surface of penes sclerotized but ventral surface membranous ( Figs. 22, 23 , 29 ).

Female: sternum 7 expanded posteriorly into obvious projection, sterna 8–9 enlarged, with a pair of distinct lateral lobes and a pair of dark dots on ventral surface, sternum 9 expanded posteriorly and posterior margin with a small median notch ( Fig. 24 ).

Distribution: Central and southern China (Guangdong, Guizhou, Fujian, Zhejiang, Anhui, Hubei provinces).

Figures

FIGURE 1. Epeorus melli (Ulmer, 1925), habitus of female.

FIGURES 2–19. Epeorus melli (Ulmer, 1925), mature nymph: 2, labrum; 3, left mandible; 4, right mandible; 5, ventral detail of incisors of right mandible; 6, maxilla; 7, hypopharynx (dorsum on left and venter on right); 8, labium (dorsum on left and venter on right); 9, foreleg; 10, midleg; 11, hindleg; 12, pectinate spines on femora; 13, foreclaw; 14, tergum 3; 15, ventral view of abdomen; 16, gill 1; 17, gill 2; 18, gill 7; 19, base of cerci.

FIGURES 20–24. Epeorus melli (Ulmer, 1925). Male imago: 20, forewing; 21, hindwing; 22, genitalia (ventral view); 23. penes (dorsum on left and venter on right); Female imago: 24, sterna 7–9.

FIGURES 25–26. Epeorus melli (Ulmer, 1925). Male nymph (photo): 25, dorsal view; 26, ventral view (showing gill disc pattern).

FIGURES 27–29. Epeorus melli (Ulmer, 1925). Male imago (photo): 27, body (abdominal terminal part excluded, showing body color pattern); 28, mid- and hind legs (showing the tarsal length); 29, genitalia (dorsal view).