Labiobaetis lubu, 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

11. Labiobaetis lubu sp. nov. Figures 18 , 19 , 48c , 54b

Diagnosis.

Larva. Following combination of characters: A) dorsal surface of labrum with submarginal arc of 21-24 clavate setae; B) labial palp segment II with a large, lobed distomedial protuberance, segment III slightly pentagonal; C) left mandible without setae at apex of mola; D) fore femur rather slender, length 3.7 × width, dorsal margin with a row of ca. 14 curved, spine-like setae and fine, simple setae; E) paraproct distally expanded, with ca. 45 stout marginal spines.

Description.

Larva ( Figs 18 , 19 , 48c ). Body length 7.2 mm.

Colouration. Head, thorax, and abdomen dorsally brown, head and thorax with bright median, dorsal suture, thorax with bright pattern as in Fig. 48c , forewing pads with bright striation. Head, thorax, and abdomen ventrally light brown, legs transparent with a brown, ventrodistomedial streak on femur, 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. 18a, 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 21-24 long, clavate setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid setae; ventral surface with five short, spine-like setae near lateral and anterolateral margin.

Right mandible ( Fig. 18c, 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. 18e, 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. 18g ). Lingua approx. as long as superlingua. Lingua longer than broad; medial tuft of stout setae well developed; distal half not expanded. Superlingua straight; lateral margin rounded; fine, long, simple setae along distal margin.

Maxilla ( Fig. 18h ). 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 four long, simple setae. Maxillary palp 1.4 × as long as length of galea-lacinia; two segmented; palp segment II 1.1 × length of segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment rounded, with excavation at inner distolateral margin.

Labium ( Fig. 18i ). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with seven spine-like setae increasing in length distally; apex with two long and one medium, robust, pectinate setae; outer margin with five spine-like setae increasing in length distally; ventral surface with short, fine, simple, scattered setae. Paraglossa sub-rectangular, curved inward; apex rounded; with three rows of long, robust, distally pectinate setae in apical area and a row of four medium, simple setae in anteromedial area; dorsally with a row of four 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 large, lobed distomedial protuberance; distomedial protuberance 0.8 × width of base of segment III; inner and outer margin with short, fine, simple setae; dorsally with two long, spine-like, simple setae near outer margin. Segment III slightly pentagonal; apex slightly truncate; length 1.1 × width; ventrally covered with short and medium spine-like, simple setae and short, fine, simple setae.

Hind wing pads absent.

Foreleg ( Fig. 19a, b, c, d ). Ratio of foreleg segments 1.2:1.0:0.4:0.1. Femur. Length ca. 4 × maximum width. Dorsal margin with a row of ca. 14 curved, spine-like setae and fine, simple setae; length of setae 0.19 × 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 absent. Tibia. Dorsal margin with a row of stout, apically rounded setae and fine simple setae. Ventral margin with a row of curved, spine-like setae, on apex some spine-like, partly bipectinate setae and a tuft of fine, simple setae. Anterior surface scattered with stout, lanceolate setae. Patellotibial suture present on basal 1/3. Tarsus. Dorsal margin almost bare. Ventral margin with a row of curved, spine-like setae. Tarsal claw with one row of 10-12 denticles; distally pointed; with three stripes; subapical setae absent.

Tergum ( Fig. 19e ). Surface with rows of U-shaped scale bases and scattered fine, simple setae. Posterior margin of tergum IV with triangular spines, wider than long.

Gills ( Fig. 19f ). 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 1/3 VI combined. Gill VII as long as length of segment VIII.

Paraproct ( Fig. 19g ). Distally expanded, with> 40 stout marginal spines. Surface scattered with U-shaped scale bases and micropores. Cercotractor with numerous small marginal spines.

Etymology.

Dedicated to the indigenous Lubu people from Sumatra.

Distribution.

Indonesia: Sumatra.

Biological aspects.

The specimens were collected in a creek at an altitude of 1,050 m.

Type-material.

Holotype. Larva (on slide, GBIFCH 00592216), Indonesia, Sumatra Barat, Bukit Barisan, above Padang, creek, 1,047 m, 08.XI.2011, 00°56.74'S, 100°32.73'E, M. Balke leg. (UN3). Temporary deposited in MZL before definitely housed in MZB. Paratypes. 4 larvae (2 on slides, GBIFCH 00592217, GBIFCH 00592218, 2 in alcohol, GBIFCH 00515342, deposited in MZL), same data as holotype.

Figures

Figure 18. Labiobaetis lubu 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 19. Labiobaetis lubu sp. nov., larva morphology: a Foreleg b Fore tibia dorsal seta c Fore femur dorsal margin d Fore claw e Tergum IV f Gill IV g Paraproct h Scape.

Figure 48. Habitus, larvae, dorsal view: a Labiobaetis weifangae sp. nov. b Labiobaetis itineris sp. nov., without head c Labiobaetis lubu sp. nov. d Labiobaetis pakpak sp. nov.

Figure 54. Distribution of Labiobaetis in Indonesia.