Labiobaetis septem, 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 septem sp. nov.

Figs 23 , 24 , 25 , 26 , 27

Type material.

Holotype. Thailand • 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 01223075 ; VMCMU . Paratypes. 18 larvae; same data as holotype; 2 on slides; GBIFCH 01223076 , GBIFCH 01221815 (legs); MZL; 16 in alcohol; GBIFCH 00829292 ; GBIFCH 00763850 ; MZL; GBIFCH 00763838 ; VMCMU • 5 larvae; 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; 1 on slide; GBIFCH 00596155 ; MZL; 4 in alcohol; GBIFCH 00763825 ; VMCMU • 1 larva; Loei Prov., Wang Saphung Distr., Nam Thob ; 17°15'37"N, 101°34'53"E; 376 m; 17.xii.2018; leg. C. Suttinun; on slide; GBIFCH 01223086 ; VMCMU • 4 larvae; Loei Prov., Wang Saphung Distr., Ban Nam Thob ; 17°16'11"N, 101°35'51"E; 318 m; 17.xii.2018; leg. C. Suttinun; 1 on slide; GBIFCH 00829294 (legs, abdomen); MZL; 3 in alcohol; GBIFCH 00763837 ; MZL • 1 larva; Chiang Mai Prov., Mae On Distr., Huai Teen Tok ; 18°52'03"N, 99°19'19"E; 760 m; 21.xi.2018; leg. C. Suttinun; on slide; GBIFCH 00607173 ; VMCMU • 1 larva; Chiang Mai Prov., Chiang Dao Distr., Huai Mae Mae ; 19°19'19"N, 98°52'51"E; 809 m; 20.xi.2018; leg. C. Suttinun; on slide; GBIFCH 01221823 ; MZL .

Other material.

Thailand • 11 larvae; Tak Prov., Mueang Distr., Klong Lan Sang ; 16°46'53"N, 99°01'16"E; 253 m; 25.xii.2017; leg. C. Suttinun; 3 on slides; GBIFCH 00607174 ; VMCMU; GBIFCH 00975857 , GBIFCH 00975858 ; MZL; 8 in alcohol; GBIFCH 00763818 , GBIFCH 00975856 , GBIFCH 00763830 ; VMCMU • 5 larvae; Tak Prov., Mueang Distr., Tha Le ; 16°44'28"N, 99°02'43"E; 327 m; 26.xii.2017; leg. C. Suttinun; 1 on slide; GBIFCH 01221817 ; MZL; 4 in alcohol; GBIFCH 00980863 ; MZL; GBIFCH 00763841 ; VMCMU • 4 larvae; Chang Mai Prov., Mae On Distr., Huai Teen Tok ; 18°52'03''N, 99°19'19''E; 760 m; 17.xi.2023; leg. C. Suttinun; VMCMU .

Diagnosis.

Larva. Following combination of characters differentiate L. septem sp. nov. from other species of the group sumigarensis : tergalii present on abdominal segments I – VII; abdomen dorsally uniform brown, or brown with crown-like pattern; femur with 9–15 spine-like setae at outer margin; tibia with row of short, apically rounded setae at outer margin, or bare with one medium, apically rounded seta distally; claw with 10–14 denticles.

Description.

Larva (Figs 23 – 26 ). Body length 3.6–4.6 mm. Cerci ~ 1 / 2 body length, paracercus ~ 1 / 3 body length. Antenna: ~ 2 × as long as head length.

Colouration (Figs 23 a – c , 24 a – c ). Head and thorax dorsally yellow-brown with dark grey pattern as in Fig. 23 a ; abdomen dorsally rather uniform brown, or brown with crown-like pattern. Fore protoptera yellow-brown to brown. Head, thorax and abdomen ventrally mainly pale grey to yellowish, abdominal segments laterally darker, and off-white along margins, abdominal segment IX darker. Legs with femur off-white to grey, with triangular, dark grey, distomedial marking at inner margin and dark grey apex; tibia yellow-brown in basal 1 / 2 and grey in distal 1 / 2; tarsus grey. Caudalii grey-brown, with dark brown distomedial section. Antennal scapus and pedicellus laterally dark grey-brown.

Antenna (Fig. 26 e ) with scape and pedicel sub cylindrical, distolateral process at scape absent.

Labrum (Fig. 25 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 ~ 17 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. 25 h ). 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, with few minute denticles. Tuft of setae on proximal corner of mola present.

Left mandible (Fig. 25 g ). Incisor and kinetodontium fused. Incisor with five denticles, kinetodontium with three denticles. Prostheca robust, apicolaterally with small denticles and comb-shaped structure. Margin between prostheca and mola straight, with minute denticles towards subtriangular process. Tuft of setae on proximal corner of mola absent.

Both mandibles with lateral margins almost straight.

Hypopharynx and superlinguae (Fig. 25 d ). Lingua approx. as long as superlinguae, 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. 25 e, f ). Galea-lacinia ventrally with two simple, apical setae below canines. Medially with one feathered, spine-like seta three medium to long, simple setae. Maxillary palp longer than length of galea-lacinia; 2 - segmented; palp segment II 1.3 × length of segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment with well-developed distolateral excavation, apically rounded.

Labium (Fig. 25 c ). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with ~ 5 spine-like setae; apex with two long and one medium, robust, apically pectinate setae; outer margin with ~ 5 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 medium, simple setae in anteromedial area; dorsally with three long, spine-like setae near inner margin. Labial palp with segment I 0.8 × length of segments II and III combined. Segment II with rounded, thumb-like, distomedial protuberance; distomedial protuberance 0.8 × width of base of segment III; dorsally with two or three spine-like setae near outer margin. Segment III subrectangular; length ~ 1.2 × maximal width; ventrally covered with short, spine-like, simple setae and short, fine, simple setae.

Hind protoptera absent.

Legs (Fig. 26 a – g ). Ratio of foreleg segments 1.2: 1.0: 0.4–0.6: 0.2, middle leg 1.1: 1.0: 0.4: 0.1, hind leg 1.2: 1.0: 0.5–0.6: 0.2. Femur. Femur length ~ 4 × maximum width. Outer margin with row of 9–15 spine-like setae; length of setae ~ 0.24 × maximum width of femur. Apex rounded, with pair of spine-like setae and some short, apically blunt setae. Stout, lanceolate, pointed setae scattered along inner margin; femoral patch rudimentary on foreleg, absent on middle and hind leg. Tibia. Outer margin with row of short, stout, apically blunt setae, distalmost seta larger, or bare with one stout, apically rounded seta distally. 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. Claw with one row of 10–14 denticles; distally pointed.

Abdominal terga (Fig. 27 a ). Surface with irregular rows of U-shaped scale bases and fine, simple, scattered setae. Posterior margin of terga: I – IX with triangular spines, I wide and short, II – IX 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. 27 b, c ). Present on segments I – VII. Margin with small denticles intercalating fine, simple setae. Tracheae partly extending from main trunk to inner and outer margins. Tergalius I small, ~ 1 / 3 length of segment II; tergalius IV somewhat longer than segment V; tergalius VII as long as segment VIII.

Paraproct (Fig. 27 d ). Distally not expanded, with ~ 29 stout, marginal spines. Surface scattered with U-shaped scale bases and fine, simple setae. Cercotractor with numerous small, marginal spines.

Remark.

The species appears with two different morphotypes, which partly share the same locations: based on our material, morphotype A is characterised by a dorsally rather uniform brown abdomen, a row of setae at outer margin of tibia, 10–15 setae at outer margin of femur, and a claw with 10 or 11 denticles; morphotype B has a crown-like pattern dorsally on the abdomen, outer margin of tibia almost bare, femur with nine or ten setae at outer margin, and claw with 12–14 denticles (see in discussion section). Holotype and paratypes correspond with morphotype A, specimens with morphotype B are mentioned as other material.

Imago.

Unknown.

Etymology.

The Latin word septem, meaning seven, refers to the seven pairs of tergalii of this species. All other known species of the group sumigarensis have only six pairs of tergalii.

Distribution.

Thailand (Fig. 32 d ).

Figures

Figure 23. Labiobaetis septem sp. nov., larva (morphotype A): a. Habitus, dorsal view; b. Habitus, ventral view; c. Abdomen, dorsal view. Scale bars: 1 mm (a, b); 100 µm (c).

Figure 24. Labiobaetis septem sp. nov., larva (morphotype B): a. Habitus, dorsal view; b. Habitus, ventral view; c. Abdomen, dorsal view. Scale bars: 1 mm (a, b); 100 µm (c).

Figure 25. Labiobaetis septem sp. nov., larva morphology: a. Labrum; b. Section of labrum, dorsal focus; c. Labium; d. Hypopharynx and superlinguae; e. Maxilla; f. Maxillary palp; g. Left mandible; h. Right mandible. Scale bars: 20 µm (c, e, g, h); 10 µm (a, b, d, f).

Figure 26. Labiobaetis septem sp. nov., larva morphology: a. Fore leg (morphotype A); b. Fore leg (morphotype B); c. Section of fore femur (morphotype A); d. Section of fore tibia (morphotype A); e. Outer margin of tibia (morphotype B); f. Inner margin of fore tibia (morphotype B); g. Fore tarsus and claw. Scale bars: 50 µm (a, b); 10 µm (c – g).

Figure 27. Labiobaetis septem sp. nov., larva morphology: a. Posterior margins of abdominal terga; b, c. Tergalius III; d. Paraproct; e. Antennal base. Scale bars: 20 µm (b); 10 µm (a, c – e).

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