Afronurus namnaoensis Braasch and Boonsoong

Braasch, Dietrich & Boonsoong, Boonsatien, 2010, A contribution to the Heptageniidae (Insecta, Ephemeroptera) of Thailand and Malaysia, Zootaxa 2610, pp. 1-26 : 2-5

Afronurus namnaoensis Braasch and Boonsoong sp. nov.

Description. Male imago: reared from larva in earthenware pot (rearing device for single larva with netterminated cover, run by depleted temperature).

Body length 6.2–6.9 mm, forewing length 6.6–7.1 mm, hind wing length 1.7–1.8 mm, length of caudal filaments 17.3 mm.

Head: Head pale yellow. Compound eyes dark. Scapes and pedicels of antennae brown, flagellae pale.

Thorax: Forewings transparent except C and Sc cells semihyaline. Forelegs: femora length 1.7 mm, tibiae length 2.2 mm, tarsi length 2.7 mm, length of tarsal segments in descending order 2=3>1=4>5. Midlegs: femora length 1.5 mm, tibiae length 1.2 mm, tarsi length 0.8 mm, length of tarsal segments in descending order: 1>2=5>3>4. Hind legs: femora length 1.8 mm, tibiae length 1.4 mm, tarsi length 0.7 mm, lengths of tarsal segments in descending order: 5>1>2>3>4. Claws of legs each with blunt, pad-like and hooked portion. Abdomen: Abdomen pale, on terga I–IX broad brown band medially, darkened posteriorly, tergum X with a pair of submedian bigger spots proximally and smaller ones distally (Fig. 1). Genitalia: Posterior margin of subgenital plate convex, combined segments 3 and 4 of forceps 1/ 3x segment 2 (Fig. 2), penial lobes divergent U-shaped, with cleft between them; apices of penial lobes expanded, each having 2 rounded angular tips (Fig. 4). Ventral penis lacking median projection (cone), rather strong titillators medially, outside curved (Fig. 3). Cerci whitish, 2.5x length of body.

Description. Female imago: Body length 6.1–6.9 mm. Length of caudal filaments 20.7 mm.

Thorax: Forewings 7.7–9.1 mm, hind wings 1.9–2.5 mm. Forelegs: femora 1.1x length of tibiae, tarsi length 2.8 mm, lengths of foretarsal segments in descending order: 2=3>1>5>4. Midlegs: femora 1.3x length of tibiae, tarsi length 0.9 mm, length of tarsal segments in descending order: 5>1>2>3=4. Hind legs: femora 1.1x length of tibiae, tarsi length 0.8 mm, lengths of tarsal segments in descending order: 1>5>2>3=4.

Abdomen: Posterior margin of anal plate convex or tongue-shaped (Fig. 5).

Description. Mature La: Length of body 4.5–6.1 mm.

Head: Head capsule 1.3x as wide as long, 1.7–1.9 mm wide, anterior margin convex, lateral margins nearly smooth, posterior margin slightly concave (Fig. 6). Antennal scapes and pedicels yellowish-brown, flagellae pale. Compound eyes black. Labrum: half as wide as head capsule, greatly expanded laterally; anterior area with dense, long hairlike setae. Mandibles: each with outer incisor longer, serrate; prosthecae consisting of tuft of 4–5 long setae; apical margin between incisor and molar areas with setae, lateral margin setaceous. Maxillae: each galea-lacinia with 13–14 pectinate spines on crown, with long hairlike setae on inner margin, with scattered hairlike setae on ventral surface, basal segment of maxillary palp with rows of hairlike setae on inner and outer margins; apical segment pointed, with rows of hairlike setae on outer margin. Hypopharynx: with lingua convex at apex, each superlingua with lateral arm developed. Labium: with Ushaped separation between glossae; paraglossae moderately expanded laterally.

Thorax: Dorsum brownish-yellow. Forelegs: femora yellow, with dark brown marks as in Fig. 7, with both short and long spines on surface, distally rounded (Fig. 8), posterior margin with fringe of long setae. Tibiae with hairlike setal field along outer margin and oblong setae, tarsi with small oblong setae and short hair sparsely. Mid- and hind legs: similar to forelegs. Claws each with 4–5 subapical denticles (Fig. 9).

Abdomen: Posterolateral spines less developed, terga yellowish, on each segment VII–IX with light markings and on each segment I–IX with row of acute spines on posterior margin. Sterna I–X whitish-yellow. Gills (Figs. 10–13): with triangular lamellae on abdominal segments II–VI, gill I leaf-like and asymmetrical, lamellae of gills V–VI each with additional projection. Caudal filament and cerci with whorls of spines, 2x length of body.

Biology: Afronurus namnaoensis is probably the most abundant species on rocks and stones in Nam Lang River and elsewhere in current waters of northern and northeastern Thailand. This species was associated with only one other, by far less abundant species of Afronurus Lestage, 1924 (former Cinygmina Kimmins, 1937 ), namely Afronurus rubromaculata ( Braasch 2006c: Thailand, Soppong, Nam Lang). However, larvae of the latter species were the only representatives of Afronurus encountered in the large River Mekong in February 2002 along the Thai-Laotic border in the utmost north of Thailand (Braasch, unpubl.). Its distribution ranges across China up to Siberian Russia.

Etymology: The name refers to the location where the species was reared: Nam Nao National Park.

PLATE I. FIGURES 1–5. Imagos of Afronurus namnaoensis sp. nov. 1, Male, abdominal tergum, color pattern. 2, Male genitalia, ventral view. 3, Penis, ventral view. 4, Penis, dorsal view. 5, Female, terminal part of sterna.

PLATE II. FIGURES 6–13. Larva of Afronurus namnaoensis sp. nov. 6, Head capsule. 7, Foreleg, dorsal view. 8, Foreleg femur, bristles on dorsal face. 9, Foreleg, tarsal claw. 10, Gill I. 11, Gill III. 12, Gill V. 13, Gill VII.

Diagnosis: Male of Afronurus namnaoensis is separated from Vietnamese Afronurus cervina by lacking a median penial cone, by the less deeply notched lobal apex, and titillators curved laterally and more medially positioned. Vietnamese A. dama presents the terminal apex of the penis slightly notched at the inner angles, whereas A. namnaoensis is recognized by somewhat elevated corners on both sides of the apices. A. rubromaculata has penis lobes deeply cleft. Chinese continental species can easily be distinguished in males, figured by Zhou and Zheng (2003: p 758, Figs.11–18). A closely related species seems to be A. rangifera ( Braasch & Soldán, 1987) from Vietnam known only in larval stage. However, its gill set (p 124, Figs. 5.1– 5.4: gill I, III, V, VII) is different from that of A. namnaoensis .

Afronurus meo and A. mnong ( Nguyen & Bae 2003) from Vietnam have larvae without gill-elongations. Whereas front of head in A. meo is with 4 light yellow round markings and gill I being broadly banana-like with rounded apex, A. namnaoensis is without front head markings but having slender gill I with sharply pointed apex. A. mnong presenting a slender banana-like gill but not pointed, has a total uniform appearance without any distinct or indistinct markings. Larvae of Afronurus species in Thailand and Vietnam mostly are with apical elongations of gill V and (or) VI. Afronurus rubromaculata is the only mainland Chinese species with elongated gill V. Afronurus species from Taiwan ( Kang & Yang 1994) are endemic island species, of which A. hyalinus ( Ulmer, 1912) shows differently elongated gills V and VI.

Discussion, Distribution. The distribution border line between the former Cinygmina and Afronurus (s. str.) runs in peninsular Malaysia, where Afronurus malaysianus and Afronurus cervina ( Braasch 2005) occur sympatric. Sites et al. (2001) recorded four undescribed morphospecies of Afronurus from southern Thailand; in our experience, relating to other species of the genus from South-East Asia ( Braasch 1990), they are expected to belong to former Cinygmina species Flowers & Pescador (1984), describing Afronurus philippinensis , commented on the generic state of Afronurus and Cinygmina : “We place A. philippinensis in Afronurus because the penes lack titillators and expanded lateral lobes, both of which occur in Cinygmina ( Braasch 1981) .” Belfiore et al. (2003) found: “By comparing the eggs of Afronurus with those of Cinygmina (Fig. 2), it is evident that in Afronurus the egg chorionic surface is almost completely covered with KCTs, a feature mainly due to the large sized equatorial KCTs (Fig. 2A), whereas in Cinygmina equatorial KCTs are smaller, thereby leaving a wide area of the chorion uncovered (Fig. 2B)” and “The shared large KCTs can be considered a synapomorphy of Afronurus and Cinygmina and highlight the close relationship between the two genera. This fact, together with nymphal similarities, could substantiate a synonymy between Afronurus and Cinygmina ”. However, we suggest that the differences as shown above could be an indication for a subgeneric concept relating to Cinygmina . Of special interest is that true Afronurus is distributed disjunctively between Africa and southern Southeast Asia including Malaysia, Great Sunda Islands, Borneo and the Philippines ( Braasch 2005; Braasch & Freitag 2008; Flowers & Pescador 1984; Kluge 2004; Mol 1987; Ulmer 1924; 1939). The distributional area of former Cinygmina is India, China, Japan, Far East Russia ( Kluge 2004) and South-East Asia up to northern Malaysia with one case of overlapping as mentioned above ( Braasch 2005). We expect lastly that genetic coding will reliably reveal the true relations between Afronurus and Cinygmina .

Material examined: HOLOTYPE: male (reared), Thailand, Chaiyaphum Province, Phronglaeng stream, 16°38’N, 101°34’E, alt. 720 m, 27.VI.2000 (BB); PARATYPES: 5 La, 1 female, 1 male (reared), same dates; 5 La, 2 females, 2 males (reared), Petchabun Province, Yakraue stream, 16°23’ N, 101°30’ E, alt. 840 m, 21.XI.2000 (BB).

Further material: 1 male, Mae Hong Son Province, Pangmapa / Soppong, Nam Lang River, 19°34’26.82’’N, 98°18’43.62’’E, alt. 605 m, 03.–27.IV.2003; at light in the evening (DB); 103 males, 31 females, 59 SI males, 21 SI females same locality, 0 1.II.–07.III.04, at light, (DB); 1 male, 21 SI males, 2 SI males, same locality, 07.VI.–18.VII.2004, at light (DK); 12 males, 48 females, 9 SI males, 6 SI females, same locality, 14.X.–17.XII.04, at light, (DK); 26 males, 15 females, 2 SI females; 130 La, same locality, 30.IV.04.– 02.VI.05, at light, bottom samples (DB); 25 males, 2 females; 82 SI males, 5 SI females, same locality, 26.I.– 30.III.07, at light (DK); 130 La, Mae Hong Son Province, Pangmapa/Soppong, Nam Lang River, 03– 27.IV.2003; bottom samples (DB); ca 30 La, same region, 10 km below Soppong, Nam Lang, 07.IV.03, bottom samples (DB); 41 La, same region, left tributary of Nam Lang, 10 km above Soppong, 04.IV.03, bottom samples (DB); ca 10 La, 10 km above Soppong, Nam Lang (Lod Cave), 05.IV.03, bottom samples (DB); 2 SI males, 1 female, 1 La, same region, Mae Nam Pai, village Mena, 19°26’N, 98°23’E, alt. ca 622 m, 26.IV.03, at light, bottom sample (DB); 9 La, same region, Nam Khom River (Wilderness Lodge), 19°21’N, 97°57’E, alt. ca 600 m, 08.IV.03, bottom samples (DB); 3 La, North Thailand, Chiang Mai Province, stream below Doi Suthep National Park, 18°48’20.05’’N, 98°55’17.01’’E, alt. ca 800 m, 19.IV.03, bottom sample (DB); ca 30 La, North Thailand, Mae Hong Son Province, Nam Khom River, near Mae Hong Son, 19°21’N, 97°57’E, alt. ca 600 m, bottom samples, 10.IV.03 (DB).

Types deposition: HOLOTYPE: male ( ZMKU); PARATYPES: 3 males, 3 females, 10 La ( ZMKU).

Further material: 25 males, 2 females, 82 SI males, 5 SI females, 2 SI males, 2 SI females ( SMF Eph); ca 50 males, 25 females, 30 SI males, 15 SI females ( MNHU); rest material (DBP).