Labiobaetis stagnum, 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 : 18-21

5. Labiobaetis stagnum sp. n. Figures 10, 11, 59a, 64a

Diagnosis.

Larva. Following combination of characters: A) labrum dorsal submarginal arc of setae composed of one plus six long, simple setae; B) maxillary palp about as long as length of galea-lacinia; C) labial palp segment II with an elongated, thumb-like distomedial protuberance; D) fore femur rather broad, length ca. 3 × maximum width, dorsal margin with a row of ca. 18 curved, spine-like setae on margin and a few stout, pointed setae near margin; E) fore claw with 10-12 denticles.

Description.

Larva (Figs 10, 11, 59a). Body length 4.5 mm; antenna: approximately twice as long as head length.

Colouration. Head, thorax and abdomen dorsally brown, head and thorax with bright median, dorsal suture, head, thorax and abdomen with bright pattern as in Fig. 59a, forewing pads with brown striation. Head, thorax and abdomen ventrally light brown, legs light brown with a brown spot distomedially on femur and medially on tibia, dorsal margin of femur brown, tarsus proximally brown. Caudal filaments light brown with a dark brown section at 3/4 of length of cerci, cerci with 2nd dark brown section near the tip.

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

Labrum (Fig. 10a). Rectangular, length 0.6 × maximum width. Distal margin with medial emargination and a small process. Dorsally with many medium to long, fine, simple setae in posterior area; submarginal arc of setae composed of one plus 5-6 long, simple setae. Ventrally with marginal row of setae composed of lateral and anterolateral long, pectinate setae and medial long, bifid, pectinate setae; ventral surface with six short, spine-like setae near lateral and anterolateral margin.

Right mandible (Fig. 10b, c). Incisors fused. Outer and inner sets of denticles with 4 + 4 denticles. Inner margin of innermost denticle with a row of thin setae. Prostheca robust, apically denticulate. Margin between prostheca and mola slightly convex. Tuft of setae at apex of mola present.

Left mandible (Fig. 10d, e). Incisors fused. Outer and inner sets of denticles with 4 + 3 (sometimes four) denticles. Prostheca robust, apically with small denticles and comb-shape structure. Margin between prostheca and mola slightly convex. Subtrian gular 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. 10f). Lingua shorter than superlingua. Lingua about as broad as long; medial tuft of stout setae present; distal half laterally expanded. Superlingua rounded; lateral margin straight; fine, long, simple setae along distal margin.

Maxilla (Fig. 10g). 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 5-6 long, simple setae. Maxillary palp slightly longer than length of galea-lacinia; two segmented. Palp segment II 1.9 × length of segment I. Setae on maxillary palp fine and simple, scattered over surface of segments I and II. Apex of last segment constricted, without excavation at inner distolateral margin.

Labium (Fig. 10h). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with 8-9 spine-like setae increasing in length distally; apex with two long and one short, robust, pectinate setae; outer margin with seven spine-like setae increasing in length distally; ventral surface with fine, simple, scattered setae. Paraglossa sub-rectangular, curved inward; apex rounded; with three rows of long, robust, apically pectinate setae: dorsally with three medium, simple setae; ventrally with five long, spine-like setae near inner margin. Labial palp with segment I 0.8 × length of segments II and III combined. Segment I covered with short, fine, simple setae ventrally and micropores dorsally. Segment II with an elongated, thumb-like distomedial protuberance; distomedial protuberance 0.6 × width of base of segment III; inner and outer margin both with short, fine, simple setae; dorsally with row of 4-5 long, spine-like, simple setae. Segment III semicircular; apex rounded; length 0.8 × width; ventrally covered with short and medium spine-like, simple setae and short, fine, simple setae.

Hind wing pads absent.

Foreleg (Fig. 11a, b). 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. 17 curved, spine-like setae and a few stout, pointed setae near margin; length of setae 0.14 × maximum width of femur. Apex rounded; with one pair of spine-like setae and some short, stout, pointed or apically rounded setae. Many stout, lanceolate setae and a few fine, simple setae along ventral margin; femoral patch well developed. Tibia. Dorsal margin with row of short, curved, spine-like setae and long, fine, simple setae and a row of stout, lanceolate setae near margin; one larger, robust, pointed seta on apex. Ventral margin with a row of curved, spine-like setae and some longer, spine-like, bipectinate setae and a tuft of long, fine, simple setae on apex. Anterior surface scattered with stout, lanceolate setae. Tibio-patellar suture present on basal 1/2. Tarsus. Dorsal margin with a row of short, curved, spine-like setae. Ventral margin with a row of curved, spine-like setae. Tarsal claw with one row of 10-12 denticles; distally pointed; with four stripes; subapical setae absent.

Tergum (Fig. 11c). Surface with irregular rows of U-shaped scale bases and scattered with fine, simple setae, scales short and apically rounded. Posterior margin of tergum IV with triangular spines, longer than wide.

Gills (Fig. 11d). Present on segments II–VII. Margin with small denticles intercalating both medium and long, 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 1/2 IX combined.

Paraproct (Fig. 11e). Distally expanded, with many marginal, stout spines. Surface with U-shaped scale bases and scattered fine, simple setae and micropores. Postero-lateral extension (cercotractor) with small marginal spines.

Etymology.

Latin word for pool, refers to the appearance in stream pools.

Distribution.

New Guinea.

Biological aspects.

The specimens were collected in stream pools at an altitude of 115 m a.s.l.

Type-material.

Holotype. Nymph (on slide, GBIFCH 00465166), Indonesia, Papua, Setani-Maribu, stream pools, 115 m, 14 Oct 2011, 02°30.51'S, 140°22.83'E, Balke (PAP01). Temporary deposited in MZL before definitely housed in MZB. Paratypes. 9 nymphs (2 on slides, GBIFCH 00465167, GBIFCH 00465168, deposited in MZL, 5 in alcohol, GBIFCH 00515227, deposited in MZL; 2 in alcohol, GBIFCH 00515228, deposited in ZSM), same data as holotype.