Labiobaetis minang, Kaltenbach, Thomas & Gattolliat, Jean-Luc, 2019

Kaltenbach, Thomas & Gattolliat, Jean-Luc, 2019, The tremendous diversity of Labiobaetis Novikova & Kluge in Indonesia (Ephemeroptera, Baetidae), ZooKeys 895, pp. 1-117 : 1

16. Labiobaetis minang sp. nov. Figures 28 , 29 , 49d , 55a

Diagnosis.

Larva. Following combination of characters: A) dorsal surface of labrum with submarginal arc of eleven medium to long, simple setae; B) maxillary palp with three segments; C) labial palp segment II with broad thumb-like distomedial protuberance, segment III oblong; D) fore femur rather slender, length 3.6 × maximum width, dorsal margin with 12-15 spine-like setae; E) posterior margin of abdominal tergites with triangular spines, wider than long and with medial enhancements; F) paraproct distally not expanded, with ca. 29 stout marginal spines.

Description.

Larva ( Figs 28 , 29 , 49d ). Body length 7.1 mm. Cerci length ca. 2/3 of body length.

Colouration. Colouration of head, thorax, and abdomen unknown due to DNA extraction from all specimens in an earlier project. Femur along dorsal and ventral margin brown, tibia and tarsus brown.

Antenna with scape and pedicel subcylindrical, with well-developed distolateral process at scape; flagellum with lanceolate spines and fine, simple setae on apex of each segment.

Labrum ( Fig. 28a ). Rectangular, length 0.8 × maximum width. Distal margin with medial emargination and a small process. Dorsally with medium, fine, simple setae scattered over surface; submarginal arc of setae composed of eleven medium to long, simple setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid, pectinate setae; ventral surface with five short, spine-like setae near lateral and anterolateral margin.

Right mandible ( Fig. 28b, c ). Incisors fused. Outer and inner sets of denticles with 4 + 3 denticles and one minute intermediate denticle. Inner margin of innermost denticle with a row of thin setae. Prostheca robust, apically denticulate. Margin between prostheca and mola straight. Tuft of setae at apex of mola present.

Left mandible ( Fig. 28d, e ). Incisors fused. Outer and inner sets of denticles with 3 + 4 denticles and one minute intermediate denticle. Prostheca robust, apically with small denticles and comb-shaped structure. Margin between prostheca and mola straight. Subtriangular process long and slender, above level of area between prostheca and mola. Denticles of mola apically constricted. Tuft of setae at apex of mola present.

Both mandibles with lateral margins almost straight. Basal half with fine, simple setae scattered over dorsal surface.

Hypopharynx ( Fig. 28f ). Lingua approx. as long as superlingua. Lingua longer than broad; medial tuft of stout setae poorly developed; distal half not expanded. Superlingua rounded; lateral margin rounded; fine, long, simple setae along distal margin.

Maxilla ( Fig. 28g ). Galea-lacinia with two simple, robust apical setae under crown. Inner dorsal row of setae with three denti-setae, distal denti-seta tooth-like, middle and proximal denti-setae slender, bifid and pectinate. Medially with one bipectinate, spine-like seta and seven or eight simple setae increasing in length distally. Maxillary palp 1.3 × as long as length of galea-lacinia; three segmented; palp segment II 1.4 × length of segment I; setae on maxillary palp fine, simple, scattered over surface of segments I, II and III; palp segment III shorter than segment II; apex of last segment slightly pointed, without excavation at inner distolateral margin.

Labium ( Fig. 28h ). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with 13 spine-like setae increasing in length distally; apex with two long and one medium, robust, pectinate setae; outer margin with ten or eleven spine-like setae; ventral surface with short, fine, simple setae. Paraglossa sub-rectangular, curved inward; apex rounded; with three rows of long, robust, distally pectinate setae in apical area and two medium, simple setae in anteromedial area; dorsally with a row of seven or eight long, spine-like setae near inner margin. Labial palp with segment I 0.8 × length of segments II and III combined. Segment I ventrally with short, fine, simple setae. Segment II with broad thumb-like distomedial protuberance; distomedial protuberance 0.6 × width of base of segment III; inner and outer margin with short, fine, simple setae; dorsally with a row of 4-6 medium, spine-like setae near outer margin. Segment III oblong; apex with small projection; length 1.3 × width; ventrally covered with short and medium spine-like, simple setae and short, fine, simple setae.

Hind wing pads absent.

Foreleg ( Fig. 29a, b ). Ratio of foreleg segments 1.3:1.0:0.7:0.2. Femur. Length ca. 4 × maximum width. Dorsal margin with a row of 12-15 curved, spine-like setae; length of setae 0.16 × maximum width of femur. Apex rounded; with one pair of curved, spine-like setae and some short, stout setae. Many stout, lanceolate, apically rounded setae scattered along the ventral margin; femoral patch well developed. Tibia. Dorsal margin with a row of short, stout setae and a few lanceolate, apically rounded setae along margin; on apex one longer, spine-like seta. Ventral margin with a row of curved, spine-like setae, on apex one bipectinate, spine-like seta and a tuft of fine, simple setae. Anterior surface scattered with stout, lanceolate setae. Patellotibial suture present on basal 2/3. Tarsus. Dorsal margin with a row of short, stout setae, on apex fine, simple setae. Ventral margin with a row of curved, spine-like setae. Tarsal claw with one row of 12 denticles; distally pointed; with five stripes; subapical setae absent.

Tergum ( Fig. 29c ). Surface with rows of U-shaped scale bases and scattered fine, simple setae. Posterior margin of tergum IV with triangular spines, wider than long and with medial enhancement.

Gills ( Fig. 29d ). Present on segments I-VII. Margin with small denticles intercalating fine simple setae. Tracheae extending from main trunk to inner and outer margins. Gill I as long as length of segment II. Gill IV as long as length of segments V and 1/2 VI combined. Gill VII as long as length of segments VIII and 1/3 IX combined.

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

Etymology.

Dedicated to the indigenous Minang people from Sumatra.

Distribution.

Indonesia: Sumatra.

Biological aspects.

The specimens were collected in altitudes of 1,640 m a.s.l. and 1,785 m a.s.l. in small (ca. 1 m wide), shallow (ca. 15 cm deep) and slow (0.15 m/s - 0.2 m/s) forest streams with partly open or closed canopy. The substrate was predominantly boulder, stones and gravel with patches of leaf litter or dead wood.

Type-material.

Holotype. Larva (on slide, GBIFCH 00422498), Indonesia, Sumatra, Volcan Singgalang, River Caruak, 00°23.05'S, 100°21.40'E, 1,640 m, 23.III.2014, M. Gueuning leg. Temporary deposited in MZL before definitely housed in MZB. Paratypes. 3 larvae (2 on slides, GBIFCH 00422537, GBIFCH 00422456, 1 in alcohol, GBIFCH 00422521, deposited in MZL), Indonesia, Sumatra, Volcan Singgalang, River Pagu Pagu, 00°23.53'S, 100°21.45'E, 1,785 m, 22.III.2014, M. Gueuning leg.

Figures

Figure 28. Labiobaetis minang sp. nov., larva morphology: a Labrum b Right mandible c Right prostheca d Left mandible e Left prostheca f Hypopharynx g Maxilla h Labium.

Figure 29. Labiobaetis minang sp. nov., larva morphology: a Foreleg b Fore claw c Tergum IV d Gill IV e Paraproct f Scape.

Figure 49. Habitus, larvae, dorsal view: a Labiobaetis paradiffundus sp. nov. b Labiobaetis rimba sp. nov., without head c Labiobaetis gueuningi sp. nov. d Labiobaetis minang sp. nov., after DNA extraction.

Figure 55. Distribution of Labiobaetis in Indonesia.