Compsoneuriella braaschi, Boonsoong & Sartori, 2015

Boonsoong, Boonsatien & Sartori, Michel, 2015, A new species of Compsoneuriella Ulmer, 1939 (Ephemeroptera: Heptageniidae) from Thailand, Zootaxa 3936 (1), pp. 123-130 : 124-130

Compsoneuriella braaschi sp. nov.

( Figs 1–3 , 5–39 )

Compsoneuria thienemanni ; sensu Boonsoong & Braasch (2013: 75) nec Compsoneuriella thienemanni Ulmer, 1939: 564

Compsoneuriella sp. 1 Sartori, 2014 , Zootaxa 3835: 26

Material examined. HOLOTYPE: male imago (reared from nymph), THAILAND, Ratchaburi Province , 13°30’33.3’’ N, 99°17’11.8’’ E, 133 m, 27.i.2014, B. Boonsoong leg. ( ZMKU). ALLOTYPE: female imago (reared from nymph), same data as holotype ( ZMKU). PARATYPES: 1 mature nymph, same data as holotype ( ZMKU); 1 male imago (reared from nymph) and 2 mature nymphs, 27.i.2014, same locale as holotype ( MZL); 9 male subimagos (reared from nymphs) and 13 mature nymphs, 12.i.2014, same locale as holotype ( ZMKU).

Additional material: 2 nymphs, THAILAND, Chiangmai Province, near Hot, Mae Nam Chaem , 18°12’07.54’’ N, 98°36’32.85’’ E; 200 m, iv.2003, D. Braasch leg. ( MZL); 2 nymphs, THAILAND, Kanchanaburi Province, Thong Pha Phum district, Ban Huai Khayeng , 14°36’20’’ N, 98°34’40’’ E, 209 m, 5.ii.2014, B. Boonsoong leg. ( ZMKU); 1 nymph, THAILAND, Prachuap Khiri Khan Province, Bang Saphan district, Klong Thong , 11°16’52’’ N, 99°25’31’’ E, 36 m, 8.vi.2014, B. Boonsoong leg. ( ZMKU).

Description. Male imago ( Fig. 2 ) (holotype in alcohol). Body length 6.50 mm; length of forewing 6.47 mm, length of hind wing 1.90 mm, length of caudal filaments 13.20 mm. Head: Width 1.87 mm; Compound eyes lavender-grey or violet-grey, contiguous. Thorax: Dorsally yellowish brown with darker brown medio-longitudinal band; Forewings ( Fig. 6 ) transparent with white shaded, black thickened cross veins and veins C and Sc yellowish brown in their proximal half. All longitudinal veins dark brown in areas where connected by cross veins; eleven thickened and brown shadowed cross veins in costal field; subcostal field with proximal cross veins mostly colourless and six thickened cross veins distally; additionally, with thickened and brown shadowed cross veins in Rs, R1, R2, and R3 fields. Hindwing ( Fig.7 ) transparent with barely discernible venation; veins C and Sc stippled with violet at base; rest of longitudinal veins whitish. Forelegs: length of femur 1.50 mm; length of tibia 1.59; length of tarsus 1.82 mm (tarsal segments in order of decreasing length: 2>3>1>4>5). Midlegs: length of femur 1.60 mm; length of tibia 1.05 mm; length of tarsus 0.75 mm (tarsal segments in order of decreasing length 1>2>3>5>4). Hind leg: length of femur 1.58 mm; length of tibia 1.17 mm; length of tarsus 0.84 mm (tarsal segments in order of decreasing length: 1>2≥5≥3>4). Femora with numerous black spots and dots, forming three darker bands on dorsal side; with two distinct transverse bands on middle of tibia; tarsal segments distally darkened ( Figs. 8–10 ). Abdomen: Dorsally with ornamentation as in Fig. 12 , with distinct median band on terga 3–4 and 6–7; laterally with pattern as in Fig. 11 , with distinct dark spot on anterior and posterior margins of abdominal terga 2–8. Genitalia with posterior margin of styliger slightly convex; basal forceps segment brownish and rounded, segments 1–4 whitish, with following proportion: 0.10: 0.50: 0.11: 0.09; forceps segment 1 short and broad, segment 4 slightly shorter than segment 3 ( Fig. 13 ); penis lobes with rounded inner and outer margins, expanded laterally and medially fused in their basal half and separated by v-shaped incision in their apical half. In ventral view ( Fig. 14 , right), apical sclerite reaching half of penis lobe width, with small basal spine; well-developed subapical spine below apical sclerite. In dorsal view ( Fig. 14 , left), lateral sclerite narrow and constricted at apex, basal sclerite well-developed, with one small and acute spine on outer margin; on inner face of lobes, two titillators strongly sinuous, their tips pointed and directed outwards ( Fig. 14 ); cerci whitish, ringed brownish.

Female imago ( Fig. 3 ) (in alcohol). Body length 8.82 mm, length of forewing 8.46 mm, length of hind wing 2.17 mm. Head: light with distinctive brown pattern; distance between eyes 6 times median ocellus width ( Fig. 15 ). Thorax: Forewings transparent with blackish, strongly brown shaded cross veins; hind wings with whitish venation. Forelegs: length of femur 2.06 mm; length of tibia 1.67; length of tarsi 1.41 mm (tarsal segments in order of decreasing length: 2>1>3>5>4). Femora with numerous black spots and dots; tibia with two distinct transverse bands; tibia and individual tarsal segments darkened distally ( Figs. 16 ). Midlegs: length of femur 2.14 mm, length of tibia 1.62 mm, length of tarsus 0.97 mm (tarsal segments in order of decreasing length 1>2>5>3>4). Femora with sparse black spots and dots; tibia as in foreleg ( Fig. 17 ). Hindlegs: length of femur 2.24 mm; length of tibia 1.53 mm; length of tarsus 0.93 mm (tarsal segments in order of decreasing length: 1≥5>2>3>4). Femora with median banding apparent; tibia as in foreleg ( Fig. 18 ). Abdomen: Light brown with median blackish brown markings as in male; parallel darker brown stripes on terga more extended than in male; middle mark in light field on tergum V ( Figs. 19–20 ). All sterna predominantly light with diffuse darker areas ( Figs 19, 21 ); both subgenital plate (sternum 7) and subanal plate (sternum 9) distally rounded ( Fig. 21 ).

Egg. Chorionic surface covered with fibrillose and rounded structures; KCTs scattered randomly across entire egg surface. Small micropyle visible on equatorial plane ( Boonsoong & Braasch 2013: Figs. 7 A–B).

Mature nymph ( Fig. 1 ) (in alcohol). Body lengths 6.08–7.33 mm (male) and 6.13–8.38 mm (female). Head widths 1.82–2.04 mm (male) and 2.21–2.44 mm (female). Caudal filaments 6.27–7.56 mm in both sexes. Head: Rectangular, anteriorly and laterally rounded, with concave hind margin; distinctive contrasting pattern consisting of six light spots near anterior margin and whitish pattern between eyes and ocelli ( Fig. 22 ). Labrum greatly expanded laterally; dorsally with dense long thin and simple setae in submarginal row; ventral side with setae and strong bristles arranged in slightly curved oblique row reaching middle ( Fig. 23 ). Mandibles strongly bent in their distal part; lateral margins with several rows of long and thin setae; right mandible ( Fig. 24 ) with outer incisor serrate on both margins, composed of ca. six teeth; inner incisor trifid; four fimbriate setae below incisors and four long and simple setae below mola; left mandible with outer incisor serrate on both margins, composed of ca. six teeth, and with subapical tooth in ventral position; inner incisor slender and pointed, bearing two seta-like structures in apical position; four fimbriate setae present below incisors, followed by tuft of short setae above mola, and five long and simple setae below mola. Maxilla with long, simple setae on inner margin of galea-lacinia and with fimbriate setae scattered on ventral surface ( Fig. 25 ); inner apical margin with proximal dentiseta bifid and fimbriate, and two distal dentisetae simple ( Fig. 26 ). Apical margin (crown) with row of 8–9 comb-shaped setae ( Fig. 26 ), which bear 10–12 teeth each. Basal segment of maxillary palp with rows of thin and simple setae on inner and outer margins; apical segment pointed, with rows of simple setae on outer margin. Hypopharynx with lingua convex at apex, rather short, without apical patch of setae and with field of ventrally fine bristles on front; superlinguae well-developed, their margins with fringes of relatively long setae reaching well beyond retrograde tips ( Fig. 27 ). Labium with U-shaped separation between glossae; shape of glossae conical, bearing two stout median setae on dorsal surface, inner margin covered with dense simple setae, outer margin with fimbriate setae ( Fig. 29 ); paraglossae moderately expanded laterally ( Fig. 28 ). Thorax: Coloration dark brown. Tibiae with two distinct transverse bands. Femora of hindlegs rather broad with dark brown markings as in Fig. 30 , consisting of three dark bands around anterior and posterior margins; posterior margin with fringe of long setae; anterior margin with similar row of slightly shorter bristles ( Fig. 30 ); dorsal surface of all femora with numerous stout bluntly pointed bristles ( Fig. 31 ). Claws adenticulate ( Fig. 32 ). Abdomen: Terga brownish with distinctive patterns; tergum II with three white spots; terga IV and VI with two yellowish dots in middle of segment; terga V and VII with two median and longitudinal pale lines; terga VIII and IX with large median pale area; tergum X with triad of three pale dots ( Fig. 33 ); posterolateral spines relatively weakly developed; posterior margins of abdominal terga with rather regularly alternating long and short teeth, submarginal rows of microdenticles poorly developed ( Fig. 35 ). Lamellate portion of all gills broadly oval and asymmetrical in general appearance; lamellae of gills I–II rounded at apex ( Fig. 36 ); gills III–VII pointed at apex, with gill VII being acutely pointed ( Figs. 37–39 ); gill V with inner margin concave near apex ( Fig. 38 ). Well-developed fibrilliform portions on gills I–VI, but absent on gill VII ( Figs. 36–39 ). Caudal filaments with whorls of small, stout, acutely pointed bristles; distal margins of alternating segments ringed with narrow black to brown bands ( Fig. 34 ).

Diagnosis. In the male imaginal stage, Compsoneuriella braaschi n. sp. is very similar to C. thienemanni , from which it can be separated by having more reduced spines on the penes lobes and by having the titillators strongly pointed at apex and directed outwards. In the nymphs, the new species can be differentiated from C. thienemanni by the following characters: 1) the maxilla bears 8–9 comb-shaped setae on the crown ( C. thienemanni bears 12 comb-shaped setae); 2) the row of setae and bristles on the ventral side of the labrum is much longer than in C. thienemanni ; 3) the glossae of the labium are more conical than in C. thienemanni ; 4) the dorsal surface of the glossae bears two setae ( C. thienemanni bears a single pointed seta); and 5) the posterior margins of the abdominal terga lack distinct rows of microdenticles. The general structure of the egg chorionic surface of C. braaschi is quite similar to C. thienemanni ( Sartori 2014) , but KCTs are randomly scattered on entire egg surface in C. braaschi , whereas the KCTs are more densely distributed near each pole in C. thienemanni .

Compsoneuriella langensis ( Braasch & Boonsoong 2010) can be distinguished from the new species by penial characters, completely brown-tinged hind wings, and shape of the glossae, tarsal claws and inner margin of fore femora ( Braasch & Boonsoong 2010; Sartori 2014).

Etymology. The specific epithet honors Dietrich Braasch (Potsdam, Germany), who has contributed greatly to the knowledge of Southeast Asian Ephemeroptera .

Biological notes. The nymphs of Compsoneuriella braaschi n. sp. were collected by sweeping the submerged bank habitat ( Fig. 4 ), with particular attention given to twigs, woody debris and leaves. The stream (width 6–7 m, water current 0.50 m /s, depth 15–20 mm at the time of collection) had a substrate composed of sand, pebbles and gravel.

Figures

FIGURES 1 – 4. Compsoneuriella braaschi sp. n. (1) male mature nymph, dorsal view; (2) male imago, lateral view; (3) female imago, dorsal view; (4) habitat of the nymphs, the Pachi River, Ratchaburi province, Thailand.

FIGURES 5 – 14. Male imago of Compsoneuriella braaschi sp. n. (5) head, dorsal view; (6) forewing; (7) hindwing; (8) foreleg; (9) middle leg (10) hindleg; (11) lateral view and (12) dorsal view of abdominal terga; (13) genitalia, ventral view; (14) penis, dorsal view (left) and ventral view (right).

FIGURES 15 – 21. Female imago of Compsoneuriella braaschi sp. n. (15) head, dorsal view; (16) foreleg; (17) middle leg (18) hindleg; (19) abdominal terga, lateral view; (20) abdominal terga, dorsal view; (21) terminal part of abdomen, ventral view.

FIGURES 22 – 29. Mature nymph of Compsoneuriella braaschi sp. n. (22) head capsule; (23) labrum, dorsal view (left) and ventral view (right); (24) right mandible; (25) left maxilla, ventral view; (26) comb-shaped setae on maxilla, apical view; (27) hypopharynx, dorsal view (left) and ventral view (right); (28) labium, dorsal view (right) and ventral view (left); (29) glossae, dorsal view (right) and ventral view (left).

FIGURES 30 – 39. Mature nymph of Compsoneuriella braaschi sp. n. (30) hindleg, left, dorsal view; (31) hindleg femur, bristles on dorsal face; (32) foreleg, tarsal claw; (33) abdominal terga I – X; (34) whorls of spines of caudal filaments; (35) posterior margin of abdominal tergum V; (36) gill I; (37) gill III; (38) gill V; (39) gill VII.