Labiobaetis paradiffundus, 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

13. Labiobaetis paradiffundus sp. nov. Figures 22 , 23 , 49a , 54b

Diagnosis.

Larva. Following combination of characters: A) dorsal surface of labrum with submarginal arc of 20-24 clavate setae; B) labial palp segment II with a large, thumb-like distomedial protuberance, segment III slightly pentagonal; C) left mandible without setae at apex of mola; D) foreleg femur rather broad, length ca. 3 × maximum width, dorsal margin with a row of ca. 16 curved, spine-like setae; E) paraproct distally expanded, with 37-48 stout marginal spines.

Description.

Larva ( Figs 22 , 23 , 49a ). Body length 6.0 mm.

Colouration. Head, thorax, and abdomen dorsally brown, head and thorax with bright median, dorsal suture, thorax with bright pattern as in Fig. 49a , abdominal segments IX and X light brown, forewing pads with dark brown striation and bright striation near margin. Head, thorax, and abdomen ventrally light brown, legs transparent, ventral margin of femur brown, caudal filaments light brown.

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

Labrum ( Fig. 22a, b ). Rectangular, length 0.7 × 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 20-24 long, clavate setae. Ventrally with marginal row of setae composed of anterolateral long, feathered setae and medial long, bifid setae; ventral surface with six short, spine-like setae near lateral and anterolateral margin.

Right mandible ( Fig. 22c, d ). 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 slightly convex, with minute denticles. Tuft of setae at apex of mola present.

Left mandible ( Fig. 22e, f ). Incisors fused. Outer and inner sets of denticles with 4 + 3 denticles and one minute intermediate denticle. Prostheca robust, apically with small denticles and comb-shaped structure. Margin between prostheca and mola straight, with minute denticles towards subtriangular process. 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 absent.

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

Hypopharynx ( Fig. 22g ). Lingua shorter than superlingua. Lingua longer than broad; medial tuft of stout setae well developed; distal half laterally expanded. Superlingua straight; lateral margin rounded; fine, long, simple setae along distal margin.

Maxilla ( Fig. 22h ). Galea-lacinia with one simple, robust apical seta 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 five long, simple setae. Maxillary palp 1.3 × as long as length of galea-lacinia; two segmented; palp segment II 1.4 × length of segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment rounded, with slight excavation at inner distolateral margin.

Labium ( Fig. 22i ). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with eight spine-like setae increasing in length distally; apex with two long and one medium, robust, pectinate setae; outer margin with 4-5 long, spine-like setae increasing in length distally; 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 four medium, simple setae in anteromedial area; dorsally with a row of three 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 0.7 × width of base of segment III; inner and outer margin with short, fine, simple setae; dorsally with a row of 3-4 long, spine-like, simple setae near outer margin. Segment III slightly pentagonal; apex slightly pointed; length 1.2 × width; ventrally covered with short and medium spine-like, simple setae and short, fine, simple setae.

Hind wing pads absent.

Foreleg ( Fig. 23a, b, c ). Ratio of foreleg segments 1.2:1.0:0.5:0.2. Femur. Length ca. 3 × maximum width. Dorsal margin with a row of ca. 16 curved, spine-like setae; length of setae 0.21 × maximum width of femur. Apex rounded; with one pair of curved, spine-like setae and some short, stout setae. Many stout, lanceolate setae scattered along the ventral margin; femoral patch poorly developed. Tibia. Dorsal margin bare. Ventral margin with a row of curved, spine-like setae, on apex two bipectinate, spine-like setae and a tuft of fine, simple setae. Anterior surface scattered with stout, lanceolate setae. Patellotibial suture present on basal 1/2. Tarsus. Dorsal margin bare. Ventral margin with a row of curved, spine-like, bipectinate setae. Tarsal claw with one row of 10-13 denticles; distally pointed; with three stripes; subapical setae absent.

Tergum ( Fig. 23d ). Surface with irregular rows of U-shaped scale bases and scattered fine, simple setae and micropores. Posterior margin of tergum IV with triangular spines, wider than long.

Gills ( Fig. 23e ). Present on segments II–VII. Margin with small denticles intercalating fine simple setae. Tracheae extending from main trunk to inner and outer margins. Gill IV as long as length of segments V and 2/3 VI combined. Gill VII as long as length of segments VIII and 1/3 IX combined.

Paraproct ( Fig. 23f ). Distally expanded, with 37-48 stout marginal spines. Surface scattered with U-shaped scale bases, fine, simple setae and micropores. Cercotractor with numerous small marginal spines.

Etymology.

Refers to the morphological similarity with L. diffundus .

Distribution.

Indonesia: Sumatra.

Biological aspects. The specimens were collected at altitudes from 890 m to 1,830 m in small to medium (0.5 m - 5 m wide), shallow (5 cm - 10 cm deep) and slow to medium fast (velocity 0.2 m/s - 0.7 m/s) forest streams or, in one case, a highly disturbed stream (agriculture, waste). The substrate was predominantly bedrock, boulder, stones, gravel and sand and only rarely with leaf litter or dead wood.

Type-material.

Holotype. Larva (on slide, GBIFCH 00592213), Indonesia, Sumatra, volcano Marapi, 00°23.65'S, 100°25.48E, 1,403 m, 04.IV.2014, M. Gueuning leg. Temporary deposited in MZL before definitely housed in MZB. Paratypes. 33 larvae (3 on slides, GBIFCH 00592214, GBIFCH 00592215, GBIFCH 00422188, 23 in alcohol, GBIFCH 00422059, GBIFCH 00422191, GBIFCH 00422054, GBIFCH 00422144, GBIFCH 00422095, GBIFCH 00422179, GBIFCH 00422212, GBIFCH 00422214, GBIFCH 00422658, GBIFCH 00422660, GBIFCH 00422164, GBIFCH 00422180, GBIFCH 00422096, deposited in MZL; 6 larvae in alcohol, GBIFCH 00515341, GBIFCH 00422139, GBIFCH 00422155, deposited in ZSM), same data as holotype.

Other material.

6 larvae (in alcohol, GBIFCH 00422131, GBIFCH 00422193, GBIFCH 00422146, GBIFCH 00422199, GBIFCH 00422161, GBIFCH 00422615), Indonesia, Sumatra, volcano Sago, Simbukan River, 00°18.93'S, 100°40.73'E, 1,645 m, 17.III.2014, M. Gueuning leg.; 2 larvae (in alcohol, GBIFCH 00422138, GBIFCH 00422171), Indonesia, Sumatra, volcano Sago, River Kaligain, 00°18.02'S, 100°40.13'E, 1,040 m, 05.IV.2014, M. Gueuning leg.; 3 larvae (in alcohol, GBIFCH 00422143, GBIFCH 00422150, GBIFCH 00422210), Indonesia, Sumatra, volcano Singgalan, River Pagu Pagu, 00°24.20'S, 100°22.72'E, 1,185 m, 22.III.2014, M. Gueuning leg.; 8 larvae (in alcohol, GBIFCH 00422169, GBIFCH 00422151, GBIFCH 00422127, GBIFCH 00422078, GBIFCH00422204, GBIFCH 00422136, GBIFCH 00422931), Indonesia, Sumatra, volcano Singgalan, River Pagu Pagu, 00°23.53'S, 100°21.45'E, 1,785 m, 22.III.2014, M. Gueuning leg.; 3 larvae (in alcohol, GBIFCH 00422091, GBIFCH 00422102, GBIFCH 00422187), Indonesia, Sumatra, volcano Singgalang, River Caruak, 00°22.93'S, 100°22.70'E, 1,300 m, 23.III.2014, M. Gueuning leg.; 1 larva (in alcohol, GBIFCH 00422189), Indonesia, Sumatra, volcano Singgalang, River Caruak, 00°23.05'S, 100°21.40'E, 1,640 m, 23.III.2014, M. Gueuning leg.; 3 larvae (in alcohol, GBIFCH 00422192, GBIFCH 00422140, GBIFCH 00422213), Indonesia, Sumatra, volcano Singgalang, River Sianok, 00°19.95'S, 100°19.32'E, 1,150 m, 24.III.2014, M. Gueuning leg.; 5 larvae (in alcohol, GBIFCH 00422196, GBIFCH 00422055, GBIFCH 00422145, GBIFCH 00422223, GBIFCH 00422172), Indonesia, Sumatra, volcano Singgalan, River Sianok, 1,350 m, 24.III.2014, M. Gueuning leg.; 7 larvae (in alcohol, GBIFCH 00422174, GBIFCH 00422202, GBIFCH 00422148, GBIFCH 00422207, GBIFCH 00422178, GBIFCH 00422137, GBIFCH 00422661), Indonesia, Sumatra, volcano Talamau, River Karumiang, 00°05.35'N, 99°58.10'E, 1,830 m, 29.III.2014, M. Gueuning leg. All material deposited in MZL.

Figures

Figure 22. Labiobaetis paradiffundus sp. nov., larva morphology: a Labrum b Seta of the submarginal arc on the dorsal surface of the labrum c Right mandible d Right prostheca e Left mandible f Left prostheca g Hypopharynx h Maxilla i Labium.

Figure 23. Labiobaetis paradiffundus sp. nov., larva morphology: a Foreleg b Fore tarsus ventral seta c Fore claw d Tergum IV e Gill IV f Paraproct g 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 54. Distribution of Labiobaetis in Indonesia.