Tenuibaetis fujitanii, Kaltenbach, Thomas & Gattolliat, Jean-Luc, 2019

Kaltenbach, Thomas & Gattolliat, Jean-Luc, 2019, A new species of Tenuibaetis Kang & Yang, 1994 from Indonesia (Ephemeroptera, Baetidae), ZooKeys 820, pp. 13-23 : 15-19

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Tenuibaetis fujitanii

sp. n.

Tenuibaetis fujitanii sp. n. Figures 1, 2, 3


Larva. Following combination of characters: A) head, thorax and abdomen dorsally brown with some darker areas as in Fig. 1a; B) labrum dorsal submarginal arc of setae composed of one plus five simple setae; C) right mandible: canine with 4+4 denticles, prostheca stick-like, apically and distolaterally denticulate; D) left mandible: canine with 3+3 denticles plus a minute intermediate denticle; E) hypopharynx without medial tuft on lingua; F) maxillary palp somewhat longer than galea-lacinia, apically rounded; G) maxilla: distal dentiseta tooth-like, middle and proximal dentisetae trifid, last furcation of proximal seta strongly developed and abducted; H) labial palp segment II slightly produced apicolaterally, segment III conical and pointed; I) fore femur dorsal margin with 19-24 curved, spine-like setae, anterior surface with 4-7 robust setae with median ridge, femoral patch strongly developed; J) fore claw with a row of 12-14 denticles; K) length of gill I 0.4 × length of gill IV; L) distal margin of paraproct with 11-14 spines, surface with a patch of notched scales.


Larva (Figs 1-3). Body length on average 4.5 mm (4.3-4.8 mm); cerci length on average 2.5 mm (2.3-2.8 mm), length of terminal filament on average 1.8 mm (1.7-2.0 mm); antenna: 2.4 × as long as head capsule length.

Colouration. Head, thorax and abdomen dorsally nearly uniformly brown with slightly darker medial areas as in Fig. 1a, abdominal segment X light brown, head and thorax with bright median, dorsal suture, forewing pads with bright striation. Head with a pair of dark spots at base of clypeus (Fig. 1c). Head, thorax and abdomen ventrally brown, slightly brighter than dorsally. Legs light brown; femur dorsal and apical margin darker brown, distomedial spot on femur darker brown; claws distally dark brown; caudal filaments brown.

Antenna with scape and pedicel sub-cylindrical, flagellum with apically rounded spines and fine, simple setae on apex of segments.

Labrum (Fig. 2a). Rectangular, length 0.7 × maximum width. Medial emargination of distal margin with a small, apically pointed process. Dorsally with many medium, fine, simple setae; submarginal arc of setae composed of one plus five 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 five short, spine-like setae near lateral and anterolateral margin.

Right mandible (Fig. 2b, c). Incisors fused. Outer and inner set of denticles with four denticles respectively. Prostheca stick-like, apically and distolaterally denticulate (Fig. 2c). Margin between prostheca and mola straight. Tuft of setae at apex of mola present.

Left mandible (Fig. 2d, e). Incisors fused. Outer and inner set of denticles with three denticles respectively, plus one minute, intermediate denticle. Prostheca robust, apically with small denticles and comb-shape structure (Fig. 2e). Margin between prostheca and mola straight. 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. 2f). Lingua about as long as superlingua; lingua longer than wide; apically triangular without medial tuft of stout setae; distal half not expanded. Superlingua with distal margin straight; lateral margins rounded; fine, long, simple setae along distal margin; short, pointed setae along lateral margin.

Maxilla (Fig. 2g). 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 denti-seta slender, trifid and pectinate, proximal denti-seta slender, trifid and pectinate and with proximal furcation strongly developed and abducted. Medially with one feathered, spine-like seta and 4-5 long, simple setae. Maxillary palp 1.1 × as long as length of galea-lacinia; two segmented. Palp segment II 1.6 × length of segment I. Fine and simple setae, scattered over surface of segments I and II. Apex of segment II rounded without nipple and without excavation at inner distolateral margin.

Labium (Fig. 2h). Glossa basally broad, narrowing toward apex; shorter than paraglossa; inner margin with nine spine-like setae increasing in length distally; apex with two long and one medium, robust, pectinate setae; outer margin with five long, spine-like setae; ventral surface with short, fine, scattered setae. Paraglossa subrectangular, slightly curved inward; apex rounded, with three rows of long, robust, apically pectinate setae; dorsally with 3-4 medium, simple setae; ventrally with an arc of six 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 only slightly produced distolaterally; inner and outer margin both with short, fine, simple setae; dorsally with a row of 5-7 long, spine-like, simple setae. Segment III conical, apex slightly pointed; length 0.9 × width; ventrally covered with short, spine-like simple setae and short, fine, simple setae.

Hind wing pads (Fig. 3d) present, well developed.

Foreleg (Fig. 3a, b). Ratio of foreleg segments 1.2:1.0:0.7:0.3. Femur. Length ca. 3 × maximum width. Dorsal margin with a row of 19-24 long, curved, lanceolate and apically rounded setae; length of setae 0.2 × maximum width of femur. Apex rounded; with one pair of clavate setae and two groups of short, stout, pointed setae. Anterior surface with 4-7 robust setae with median ridge. Stout, lanceolate setae along ventral margin; femoral patch strongly developed. Tibia. Dorsal margin with a row of short, stout, pointed setae and rare long, fine, simple setae. Ventral margin with a row of short, spine-like setae, on apex one stout, pointed seta and a tuft of fine, simple setae. Anterior surface scattered with stout, lanceolate setae. Tibio-patelar suture present on basal 2/3 area. Tarsus. Dorsal margin with a row of short, stout, pointed setae. Ventral margin with a row of curved, spine-like setae. Tarsal claw with one row of 12-14 denticles and with seven stripes apically; claw distally pointed and curved; subapical setae absent.

Tergum (Fig. 3c). Surface with scattered U-shaped scale bases and scattered fine, simple setae. Posterior margin of tergum IV with mostly rounded spines, wider than long.

Gills (Fig. 3e, f). Present on segments I–VII. Margin with small denticles intercalating fine, simple setae. Tracheae limited to proximal part of main trunk. Gill I as long as ⅔ of length of segment II; gill IV as long as length of segment V and ½ of segment VI combined, 2.3 × length of gill I; gill VII as long as length of segment VIII.

Paraproct (Fig. 3g, h). Distally not expanded, with 11-13 marginal, stout spines. Surface with U-shaped scale bases, micropores and fine, simple setae, and with a patch of notched scales (Fig. 3h). Posterior extension (cercotractor) with medium, marginal spines.


This species is dedicated to Dr Toshihito Fujitani (Japan), who contributed much to the knowledge of the genus Tenuibaetis .


Java (Indonesia).


Holotype. Nymph (on slide, GBIFCH00465233), Indonesia, Java, Bogor (downstream the botanical garden), Ciliwung riv, 235 m, 06°35'32"S, 106°48'00"E, 01.05.2010, Jean-Marc Elouard leg. Paratypes. 13 nymphs (3 on slides, GBIFCH00465232, GBIFCH00465234, GBIFCH00465235; 10 in alcohol, GBIFCH00515308, GBIFCH00657733, GBIFCH00657755, GBIFCH00657782), same data as holotype. All material deposited in Museum of Zoology Lausanne (MZL).