Labiobaetis paranumeratus, 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

18. Labiobaetis paranumeratus sp. nov. Figures 31 , 32 , 50a , 54b

Diagnosis.

Larva. Following combination of characters: A) dorsal surface of labrum with submarginal arc of 1 + 8 medium to long, simple setae, the first two setae after the central seta are closely together; B) right mandible with a pronounced hump between prostheca and mola; C) labial palp segment II with a broad thumb-like distomedial protuberance, segment III conical; D) fore femur rather broad, length ca. 3 × maximum width, dorsal margin with ca. seven spine-like setae, apically rounded and with minute serration, close to margin some spine-like setae, apically rounded and with minute pectination; E) paraproct distally not expanded, with ca. 17 stout marginal spines and some submarginal spines.

Description.

Larva ( Figs 31 , 32 , 50a ). Body length 4.3-4.7 mm. Cerci ca. 2/3 length of abdomen. Terminal filament: approx. as long as cerci.

Colouration. Head, thorax, and abdomen dorsally brown, head and thorax with bright median, dorsal suture, forewing pads light brown with darker striation. Head, thorax, and abdomen ventrally brown, legs transparent, femur distomedially with a brown spot, tibia distomedially and tarsus proximally brown. Caudal filaments light brown, with a dark brown band at 2/3 of cerci.

Antenna with scape and pedicel subcylindrical, without distolateral process at scape; flagellum with broad, apically blunt spines and fine, simple setae on apex of each segment.

Labrum ( Fig. 31a ). 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 1 + 8 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 seven short, spine-like setae near lateral and anterolateral margin.

Right mandible ( Fig. 31b, 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 with a pronounced hump. Tuft of setae at apex of mola present.

Left mandible ( Fig. 31d, e ). Incisors fused. Outer and inner sets of denticles with 4 + 3 denticles. Prostheca robust, apically with small denticles and comb-shaped structure. Margin between prostheca and mola slightly convex, with minute denticles toward 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 present.

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

Hypopharynx ( Fig. 31f ). Lingua longer than superlingua. Lingua longer than broad; medial tuft of stout setae poorly developed; distal half laterally expanded. Superlingua straight; lateral margin rounded; fine, long, simple setae along distal margin.

Maxilla ( Fig. 31g ). 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 or five long, simple setae. Maxillary palp 1.6 × as long as length of galea-lacinia; two segmented; palp segment II 1.6 × length of segment I; setae on maxillary palp fine, simple, scattered over surface of segments I and II; apex of last segment rounded, without excavation at inner distolateral margin.

Labium ( Fig. 31h ). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with eight spine-like setae, distalmost seta much longer than other setae; apex with two long and one medium, robust, pectinate setae and one short, robust seta; outer margin with six long spine-like setae increasing in length distally; ventral surface with short, fine, simple and short, spine-like 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 six long, spine-like setae near inner margin. Labial palp with segment I 0.9 × 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 0.8 × width of base of segment III; inner and outer margin with short, fine, simple setae; dorsally with a row of four short to medium, spine-like, simple setae near outer margin. Segment III conical; apex rounded; length 0.9 × width; ventrally covered with short and medium spine-like, simple setae and short, fine, simple setae.

Hind wing pads minute.

Foreleg ( Fig. 32a, b, c, d, e ). Ratio of foreleg segments 1.3:1.0:0.6:0.2. Femur. Length ca. 3 × maximum width. Dorsal margin with a row of ca. seven spine-like setae, apically rounded and with minute serration, close to margin some spine-like setae, apically rounded and with minute serration; length of setae 0.27 × maximum width of femur. Apex rounded; with one pair of spine-like setae, apically rounded and with minute pectination and with some short, stout setae. Many stout, lanceolate setae scattered along the ventral margin; femoral patch absent. Tibia. Dorsal margin with a row of stout setae, apically rounded and with minute pectination; on apex one pair of long, stout setae, apically rounded and with minute pectination. Ventral margin with a row of curved, spine-like setae, on apex some spine-like, bipectinate 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 almost bare. Ventral margin with a row of curved, spine-like setae. Tarsal claw with one row of 13-14 denticles; distally pointed; with five stripes; subapical setae absent.

Tergum ( Fig. 32f ). Surface with irregular rows of scale bases and scattered micropores. Posterior margin of tergum IV with rounded spines, wider than long.

Gills ( Fig. 32g ). 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 2/3 IX combined.

Paraproct ( Fig. 32h ). Distally not expanded, with 16-19 stout marginal spines and some submarginal 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. numeratus .

Distribution.

Indonesia: Sumatra.

Biological aspects.

The specimens were collected at an altitude of 520 m.

Type-material.

Holotype. Larva (on slide, GBIFCH 00592210), Indonesia, Sumatra Barat, Harau Canyon, stream near Ikbal's cottage, 520 m, 23.VI.2012, 00°06.44'S, 100°40.37'E, M. Balke leg. (UN11). Temporary deposited in MZL before definitely housed in MZB. Paratypes. 2 larvae (on slides, GBIFCH 00592211, GBIFCH 00592212, deposited in MZL), same data as holotype.

Figures

Figure 31. Labiobaetis paranumeratus 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 32. Labiobaetis paranumeratus sp. nov., larva morphology: a Foreleg b Fore femur dorsal seta c Fore tibia dorsal seta d Fore tibia dorsal, apical seta e Fore claw f Tergum IV g Gill IV h Paraproct i Metanotum.

Figure 50. Habitus, larvae, dorsal view: a Labiobaetis paranumeratus sp. nov. b Labiobaetis pilosus sp. nov. c Labiobaetis seramensis sp. nov. d Labiobaetis wahai sp. nov.

Figure 54. Distribution of Labiobaetis in Indonesia.