Labiobaetis dendrisetis, Kaltenbach, Thomas & Gattolliat, Jean-Luc, 2018

Kaltenbach, Thomas & Gattolliat, Jean-Luc, 2018, The incredible diversity of Labiobaetis Novikova & Kluge in New Guinea revealed by integrative taxonomy (Ephemeroptera, Baetidae), ZooKeys 804, pp. 1-136 : 89-91

26. Labiobaetis dendrisetis sp. n. Figures 48, 49, 65b

Diagnosis.

Larva. Following combination of characters: A) labrum dorsal submarginal arc of setae composed of one plus 5 long, dendritic, apically pointed setae and 3 middle to long, simple setae; B) both mandibles with outermost denticles blade-like; C) maxillary palp somewhat shorter than length of galea-lacinia; D) distomedial protuberance of labial palp segment II short, thumb-like; E) fore femur rather broad, length ca. 3 × maximum width, dorsal margin with a row of ca. 20 curved, spine-like setae and basally a row of robust, spine-like setae near margin; F) tarsal claw with one row of seven denticles and without striation.

Description.

Larva (Figs 48, 49). Antenna approximately twice as long as head length.

Colouration. Unknown.

Antenna with scape and pedicel sub-cylindrical, without distolateral process at scape; flagellum with lanceolate spines on apex of each segment.

Labrum (Fig. 48a, b). Rectangular, length 0.5 × maximum width. Distal margin with medial emargination and a small process. Dorsally with medium, fine, simple setae scattered over surface; submarginal dorsal arc of setae composed of one plus five long, dendritic, apically pointed setae and three middle to long, simple setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, feathered setae and medial long, bifid setae; ventral surface with ten short, spine-like setae near lateral and anterolateral margin.

Right mandible (Fig. 48c, d). Incisors fused. Outer and inner sets of denticles unknown, outermost denticle blade-like. Inner margin of innermost denticle with a row of thin setae. Prostheca robust, apically denticulate. Margin between prostheca and mola straight, with minute setae. Tuft of setae at apex of mola present.

Left mandible (Fig. 48 e–h). Incisors fused. Outer and inner sets of denticles with 3 + 3 denticles, outermost denticle blade-like. Prostheca robust, apically with small denticles and comb-shape structure. Margin between prostheca and mola straight, with minute setae. 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. 48i). Lingua longer than superlingua. Lingua longer than broad; medial tuft of stout setae present; distal half laterally expanded. Superlingua rounded; lateral margin straight; fine, long, simple setae along distal margin.

Maxilla (Fig. 48j). 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 9-10 long, simple setae. Maxillary palp somewhat shorter than length of galea-lacinia; two segmented. Palp segment II 1.8 × length of segment I. Setae on maxillary palp fine and simple, scattered over surface of segment II and along outer margin of segment I. Apex of last segment rounded, with slight excavation at inner distolateral margin.

Labium (Fig. 48k). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with five spine-like setae increasing in length distally; apex with three long, robust setae; outer margin with 3-4 long, spine-like setae; ventral surface with few short, fine, simple setae. Paraglossa sub-rectangular, curved inward; apex rounded; with three rows of long, robust, apically pectinate setae; dorsally with two medium, simple setae; ventrally with three long, spine-like setae near inner margin. Labial palp with segment I 0.6 × length of segments II and III combined. Segment I dorsally covered with micropores and ventrally with fine, simple setae along margins. Segment II with a short, thumb-like distomedial protuberance; distomedial protuberance 0.2 × width of base of segment III; inner and outer margin both with short, fine, simple setae; dorsally with row of six spine-like, simple setae, decreasing in length distally. Segment III semicircular; apex rounded; length 0.8 × width; covered with long and medium spine-like, simple setae and short, fine, simple setae.

Hind wing pads absent.

Foreleg (Fig. 49a, b). Ratio of foreleg segments 1.8:1.0:0.6:0.2. Femur. Length ca. 3 × maximum width. Dorsal margin with a row of ca. 20 curved, spine-like setae, basally a row of robust, spine-like setae near margin; length of setae 0.18 × maximum width of femur. Apex rounded; with one pair of curved, spine-like setae and many short, stout, pointed setae. Ventral margin with a row of short, spine-like setae, some stout, lanceolate, pointed setae and a few fine, simple setae scattered along ventral margin; femoral patch absent. Tibia. Dorsal margin with a few short, curved, spine-like setae and a pair of longer, curved, spine-like setae on apex. Ventral margin with a row of curved, spine-like setae, on apex one stout, spine-like seta and a tuft of long, fine, simple setae. Anterior surface scattered with many stout, lanceolate setae. Tibio-patellar suture present on basal 1/2. Tarsus. Dorsal margin with one or two short, spine-like setae near apex. Ventral margin with a row of curved, spine-like setae. Tarsal claw with one row of seven denticles; tapering distally; striation absent.

Tergum (Fig. 49c). Surface with irregular rows of W-shaped scale bases, scales broad, apically rounded. Posterior margin of tergum IV with triangular or pentagonal spines, about as long as wide.

Gills (Fig. 49d). Present on segments I–VII. Margin with small denticles intercalating long, fine, simple setae. Tracheae partly extending from main trunk towards outer and inner margins. Gill I as long as length of segment II. Gill IV as long as length of segments V and VI combined. Gill VII as long as length of segments VIII and 1/3 IX combined.

Paraproct (Fig. 49e). Distally not expanded, with many marginal, stout spines. Surface with W-shaped scale bases and scattered fine, simple setae and micropores. Postero-lateral extension (cercotractor) with small marginal spines.

Etymology.

Refers to the dendritic submarginal setae on dorsal surface of labrum.

Distribution.

New Guinea.

Biological aspects.

The specimens were collected in forest at an altitude of 2900 m a.s.l.

Type-material.

Holotype. Nymph (on slide, GBIFCH 00465217), Papua New Guinea, Simbu Prov., 05°49.00'S, 145°04.50'E, Mt. Wilhelm, Pindaunde Creek, 2900 m a.s.l. (in forest), S3 (oria.4), 18 Aug 1999, leg. L. Čížek. Deposited in MZL. Paratype. 1 nymph (on 2 slides, GBIFCH 00465218, deposited in MZL), same data as holotype.