Labiobaetis centralensis, 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 : 84-89

25. Labiobaetis centralensis sp. n. Figures 46, 47, 63a, 65a

Diagnosis.

Larva. Following combination of characters: A) labrum with dorsal submarginal arc of setae composed of one plus six long, simple setae; B) labial palp segment II with an elongated, thumb-like distomedial protuberance; C) maxillary palp slightly longer than length of galea-lacinia, segment II apically slightly pointed and without excavation at inner lateral margin; D) right mandible outer and inner sets of denticles with 4 + 4 denticles respectively plus one small intermediate denticle; E) left mandible outer and inner sets of denticles with 4 + 4 denticles respectively; F) fore femur slender, length ca. 4 × maximum width, dorsal margin with a row of ca. 21 curved, spine-like setae and distally a row of robust, spine-like setae close to margin.

Description.

Larva (Figs 46, 47, 63a). Body length 4.8 mm.

Colouration. Head, thorax and abdomen dorsally brown, with bright pattern as in Fig. 63a. Head and thorax with bright median, dorsal suture, forewing pads with bright striation. Head, thorax, and abdomen ventrally colourless, femur, tibia, and tarsus with brown dorsal margin, legs otherwise colourless, caudal filaments brown.

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

Labrum (Fig. 46a). Rectangular, length 0.6 × 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 one plus six long, simple setae. Ventrally with marginal row of setae composed of anterolateral long, feathered setae and medial long, bifid, pectinate setae; ventral surface with four short, spine-like setae near lateral and anterolateral margin.

Right mandible (Fig. 46b, c). Incisors fused. Outer and inner sets of denticles with 4 + 4 denticles plus one small 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. 46d, e). Incisors fused. Outer and inner sets of denticles with 4 + 4 denticles. Prostheca robust, apically with small denticles and comb-shape struc ture. 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 not 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. 46f). Lingua longer than superlingua. Lingua about as broad as long; medial tuft of stout setae present; distal half laterally expanded. Superlingua rounded; lateral margin rounded; fine, long, simple setae along distal margin.

Maxilla (Fig. 46g). 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 spine-like seta and six long, simple setae. Maxillary palp slightly longer than length of galea-lacinia; two segmented. Palp segment II about as long as segment I. Fine and simple setae scattered over surface of segment II. Apex of segment II slightly pointed, without excavation at inner distolateral margin.

Labium (Fig. 46h). 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 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 row of three medium, simple setae; ventrally with five medium, spine-like setae near inner margin. Labial palp with segment I 0.7 × length of segments II and III combined. Segment I dorsally covered with micropores. Segment II with an elongated, thumb-like distomedial protuberance; distomedial protuberance 0.5 × width of base of segment III; inner margin with few fine, simple setae; outer margin bare; dorsally with row of four long, spine-like, simple setae. Segment III conical; apex rounded; ventrally covered with medium spine-like, simple setae and short, fine, simple setae.

Hind wing pads absent.

Foreleg (Fig. 47 a–d). Ratio of foreleg segments 1.2:1.0:0.5:0.2. Femur. Length ca. 4 × maximum width. Dorsal margin with a row of ca. 21 curved, spine-like setae, distally a row of robust, spine-like setae close to margin, and a row of fine simple setae along margin; length of setae 0.1 × maximum width of femur. Apex rounded; with two pairs of spine-like setae, many short, stout, blunt setae and some fine, long, simple setae. Many stout, lanceolate setae and a few fine, simple setae along ventral margin; femoral patch well developed. Tibia. Dorsal margin with stout, lanceolate, apically rounded setae and very fine, simple setae along margin. Ventral margin with a row of curved, spine-like setae, one seta on apex much longer; one long, bipectinate seta and a tuft of fine, long, simple setae on apex. Anterior surface scattered with many stout, lanceolate setae. Tibio-patellar suture present on basal 1/2. Tarsus. Dorsal margin with a row of short, spine-like setae and fine, simple setae along margin, especially on apex. Ventral margin with a row of curved, spine-like setae. Tarsal claw with one row of 10-11 denticles; distally pointed; with five stripes; subapical setae absent.

Tergum (Fig. 47e). Surface with irregular rows of U-shaped scale bases and scattered fine, simple setae and micropores, scales short, apically rounded. Posterior margin of tergum IV with triangular spines, about as long as wide.

Gills (Fig. 47f). Present on segments II–VII. Margin with small denticles intercalating long, fine, simple setae. Tracheae extending from main trunk to inner and outer margins, pigmentation limited to part of main trunk and one or two extensions to inner margin only. Gill IV as long as length of segments V and 1/2 VI combined. Gill VII as long as length of segments VIII and 1/2 IX combined.

Paraproct (Fig. 47g). Distally slightly expanded, with many marginal, stout spines. Surface with U-shaped scale bases and scattered fine, simple setae. Postero-lateral extension (cercotractor) with small marginal spines.

Etymology.

Refers to the type locality in the Central Province of Papua New Guinea.

Distribution.

New Guinea.

Biological aspects.

The specimens were collected at an altitude of 590 m a.s.l.

Type-material.

Holotype. Nymph (on slide, GBIFCH 00465215), Papua New Guinea, Central, Kokoda Trek, 590 m, 01.2008, 09°14.34'S, 147°36.92'E, Posman (PNG170). Deposited in ZSM. Paratypes. 16 nymphs (1 on slide, GBIFCH 00465216, 8 in alcohol, GBIFCH 00515217, deposited in MZL; 7 in alcohol, GBIFCH 00515218, deposited in ZSM), same data as holotype.