Labiobaetis karen, Kaltenbach & Gattolliat & Boonsoong & Suttinun, 2025

Kaltenbach, Thomas, Gattolliat, Jean-Luc, Boonsoong, Boonsatien & Suttinun, Chanaporn, 2025, New species of Labiobaetis Novikova & Kluge from Thailand (Ephemeroptera, Baetidae), ZooKeys 1258, pp. 213-276 : 213-276

Labiobaetis karen sp. nov.

Figs 20 , 21 , 22

Type material.

Holotype. Thailand • larva; Kanchanaburi Prov., Thong Pha Phum Distr., Pra Chum Mai ; 14°34'58"N, 98°34'52"E; 269 m; 25.v.2017; leg. C. Suttinun; on slide; GBIFCH 00763836 ; VMCMU . Paratypes. 2 larvae; same data as holotype; on slides; GBIFCH 00980859 , GBIFCH 01221814 ; MZL • 1 larva; Tak Prov., Mueang Distr., Klong Lan Sang ; 16°46'53"N, 99°01'16"E; 253 m; 25.xii.2017; leg. C. Suttinun; on slide; GBIFCH 00592515 ; VMCMU .

Diagnosis.

Larva. Following combination of characters differentiate L. karen sp. nov. from other species of the group sumigarensis : thorax dorsally ochre, with dark brown distolateral dots on mesonotum; abdomen dorsally dark reddish-brown, paler in middle area, segment I ochre; femur with dark brown, triangular marking at inner, distomedial margin; tibia dark brown in subdistal area; scapus and pedicellus laterally with dark brown hypodermal colouration; labial palp segment III subrectangular with inner distal margin concave; paraproct distally not expanded.

Description.

Larva (Figs 20 – 22 ). Body length 3.5–4.7 mm. Caudalii ~ 1 / 2 body length, paracercus ~ 0.4 × body length. Antenna: ~ 2 × as long as head length.

Colouration (Fig. 20 a – c ). Head and thorax dorsally ochre, head and pronotum with dark brown markings, mesonotum with pronounced dark brown distolateral dots as in Fig. 20 a ; abdomen dorsally dark reddish-brown, paler in middle area, laterally pale brown, segment I ochre. Fore protoptera ochre. Head, thorax and abdomen ventrally mainly beige, abdominal segments laterally dark reddish brown. Legs pale brown, femur with dark brown, triangular marking at inner, distomedial margin, dark brown streak at outer margin, and dark brown marking at apex; tibia dark brown in subdistal area. Caudalii pale brown. Antennal scapus and pedicellus with dark brown hypodermal, lateral colouration.

Antenna (Fig. 22 j ) with scape and pedicel sub cylindrical, distolateral process at scape absent.

Labrum (Fig. 21 a, b ). Sub-rectangular, length 0.7 × maximum width. Distal margin with medial emargination and small process. Dorsally with medium, fine, simple setae scattered over surface; submarginal arc of ~ 15 long, clavate setae on each side. Ventrally with marginal row of setae composed of anterolateral long, feathered setae and medial long, bifid setae.

Right mandible (Fig. 21 i ). Incisor and kinetodontium fused. Incisor with five denticles; kinetodontium with three denticles, inner margin of innermost denticle with row of thin setae. Prostheca robust, apically denticulate. Margin between prostheca and mola almost straight. Tuft of setae on proximal corner of mola present.

Left mandible (Fig. 21 h ). Incisor and kinetodontium fused. Incisor with five denticles, kinetodontium with four denticles. Prostheca robust, apicolaterally with small denticles and comb-shaped structure. Margin between prostheca and mola straight. Tuft of setae on proximal corner of mola absent.

Both mandibles with lateral margins almost straight.

Hypopharynx and superlinguae (Fig. 21 e ). Lingua approx. as long as superlinguae. Lingua longer than broad, subdistally slightly expanded; medial tuft of stout setae well developed. Superlinguae with lateral margins rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 21 f, g ). Galea-lacinia ventrally with two simple, apical setae below canines. Medially with one feathered, spine-like seta and four or five medium to long simple setae. Maxillary palp longer than length of galea-lacinia; 2 - segmented; palp segment II slightly longer than segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment with distolateral excavation, apically rounded.

Labium (Fig. 21 c, d ). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with ~ 7 robust, spine-like setae, distalmost seta longer; apex with two long and one medium, robust, apically pectinate setae; outer margin with ~ 3 spine-like setae; ventral surface with fine, simple, scattered setae. Paraglossa sub-rectangular, slightly curved inward; apex rounded; with three rows of long, robust, distally pectinate setae in apical area and three or four medium, simple setae in anteromedial area; dorsally with four long, spine-like setae near inner margin. Labial palp with segment I approx. as long as segments II and III combined. Segment II with rounded, thumb-like, distomedial protuberance; distomedial protuberance 0.7 × width of base of segment III; dorsally with two spine-like setae near outer margin. Segment III subrectangular, inner distal margin slightly concave; length approx. as maximal width; ventrally covered with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera absent.

Legs (Fig. 22 a – e ). Ratio of foreleg segments 1.2: 1.0: 0.5: 0.2, middle leg 1.1: 1.0: 0.4: 0.2, hind leg 1.2: 1.0: 0.4: 0.2. Femur. Femur length ~ 3.5 × maximum width. Outer margin with row of 10–12 spine-like setae; length of setae ~ 0.19 × maximum width of femur. Apex rounded, with pair of spine-like setae and short, stout, apically blunt setae. Stout, lanceolate, pointed setae scattered along inner margin; femoral patch absent on fore and middle legs, rudimentary on hind leg. Tibia. Outer margin with row of short, stout, apically blunt setae, distalmost seta larger. Inner margin with two rows of medium spine-like setae; on apex tuft of fine, simple setae. Patella-tibial suture present on basal 1 / 3. Tarsus. Outer margin almost bare. Inner margin with row of curved, spine-like setae increasing in length distally. Claw with one row of 9–12 denticles; distally pointed.

Abdominal terga (Fig. 22 h ). Surface with irregular rows of U-shaped scale bases and fine, simple, scattered setae. Posterior margin of terga: I smooth, without spines, II – IX with triangular, pointed spines, becoming longer and sharper toward end of abdomen.

Abdominal sterna. Posterior margin of sterna: I – VI smooth, without spines; VII – IX with triangular spines.

Tergalii (Fig. 22 f, g ). Present on segments II – VII. Margin with small denticles intercalating fine, simple setae. Tracheae partly extending from main trunk to inner and outer margins. Tergalius IV somewhat longer than segments V; tergalius VII as long as segment VIII.

Paraproct (Fig. 22 i ). Distally not expanded, with ~ 32 stout, marginal spines. Surface scattered with U-shaped scale bases and fine, simple setae. Cercotractor with numerous small, marginal spines.

Imago.

Unknown.

Etymology.

The species is dedicated to the indigenous Karen people in Thailand.

Distribution.

Thailand (Fig. 32 d ).

Figures

Figure 20. Labiobaetis karen sp. nov., larva: a. Habitus, dorsal view; b. Habitus, ventral view; c. Abdomen, dorsal view. Scale bars: 1 mm (a, b); 100 µm (c).

Figure 21. Labiobaetis karen sp. nov., larva morphology: a. Labrum; b. Section of labrum, dorsal focus; c. Labium; d. Labial palp; e. Hypopharynx and superlinguae; f. Maxilla; g. Maxillary palp; h. Left mandible; i. Right mandible. Scale bars: 20 µm (c, e, f, h, i); 10 µm (a, b, d, g).

Figure 22. Labiobaetis karen sp. nov., larva morphology: a. Fore leg; b. Outer margin of fore femur; c. Inner margin of fore femur; d. Section of fore tibia; e. Fore claw; f, g. Tergalius III; h. Posterior margins of abdominal terga; i. Paraproct; j. Antennal base. Scale bars: 50 µm (a); 20 µm (f); 10 µm (b – e, g – j).

Figure 32. Distribution maps: a. Labiobaetis batakorum species group; b. Labiobaetis numeratus species group; c. Labiobaetis operosus species group; d. Labiobaetis sumigarensis species group.