Dysphaea gloriosa Fraser, 1938

Nguyen, Minh Ty, Ignatius, Kaewpawika Jitthamma, Sunprasit, Somneuk, Phan, Quoc Toan & Keetapithchayakul, Tosaphol Saetung, 2024, Description of final stadium larva of Dysphaea gloriosa Fraser, 1938, (Odonata: Euphaeidae) with notes on its habitat and biology, Zootaxa 5447 (3), pp. 385-396 : 386-395

Description of larva of Dysphaea gloriosa Fraser, 1938

Material examined. THAILAND. 2 exuviae: 1 ♁ (collected from stream, old and partly torn), 27/II/2021, Haew Suwat at Khao Yai National Park (14° 26’ 01.0” N, 101° 24’ 56.6” E, elevation 683 m a.s.l.), Nakhon Ratchasima province, T.S. Keetapithchayakul leg. ; 1 ♁, 15/XII/2023, Kong Keaw waterfall, Khao Yai National Park (14° 26’ 21.8” N, 101° 22’ 25.6” E, elevation 743 m a.s.l.), Nakhon Ratchasima province, T.S. Keetapithchayakul leg. , 7 late stadium larvae:, 2 ♁♁,(F-1), 2 ♀♀, (F-1), 1 undetermined sex (F-2), 15/XII/2023, Kong Keaw waterfall at Khao Yai National Park (14° 26’ 21.8” N, 101° 22’ 25.6” E, elevation 743 m a.s.l.), Nakhon Ratchasima province, K.J. Ignatius and T.S. Keetapithchayakul leg.

Description of larva based on 1 ♁ (exuvia) and 1 ♀ (F-0). Habitus ( Figs 1 , 2 ) stout but moderately elongate with an enormous flattened head with heavy spines on genae and strongly convex postocular lobes, long robust legs with broad flattened femora, abdomen semi-cylindrical, tapered caudad, with seven pairs of ventral gills on S2–8, caudal gills saccoid, and gradually tapering; coloration variable, brownish to brownish-black.

Head: flattened, both broad and elongate in outline with strongly rounded margins; width / length ratio of ca 1.2. Antennae ( Fig. 3A ), 8-segmented, with A2 longest, relative length of antennomeres 0.62: 1.00 (0.78 mm): 0.69: 0.79: 0.96: 0.60: 0.37: 0.33, A1–A8 with scattered small SS, and A1 with tuff of CVS. Labrum ( Figs 1 , 2A , 3B–C ) forming a rounded low pentangular shape, broad with pronounced central apex, fringed with long SS distally and scattered CVS on basal half, the longest distinctly curved; clypeus rather bulbous, antefrons scattered small SS and CVS, with 2 pairs of elongated tubercles ( Fig. 3B ); vertex with 3 prominent ocelli; compound eyes broad and rounded, slightly protruding antero-laterally; Postocular lobes strongly swollen and rounded in outline, so that posterior margin of head is deeply convex, with a narrow flange at posterior occipital margin, fitting closely to anterior dome of prothorax ( Figs 1 , 2A , 3C ); outer margins of postocular lobes bearing numerous short strong spines, not all aligned ( Fig. 3D ); entire occiput with scattered small SS. Intermingled with small CVS and SS that together create a distinct pattern of dark, roughly parallel, longitudinal ridges running across the lobes to the eye margins. In dorsal view ( Fig. 3C ) outer part of mandibles, anterior angles of prementum, and labial palps all visible expanding beyond labrum, Genae ( Fig. 3C–D ) swollen well beyond eyes with complex margin of strong sharp spines, diminishing in size posteriorly where they are continuous with the slightly shorter postocular marginal spines; interspersed among the dominant spines are small SS and SLS; regular SS and CVS on ventro-internal view ( Fig. 3D ). Articulation of labial prementum and postmentum reaching between posterior margin of head and anterior margin of foreleg. Prementum ( Fig. 4A ) wedge-shaped with distinctly sinuous, laterodistal margin with 2 distinct spines, lateral margins bearing distinct serration (20–25 spines) each spine bearing SS, for most of their length; distally wider than 0.91 length, with a pair of SS on middle of ventro-posterior side in ventral view; distal ¼ heavily infuscated; ligula (median lobe) produced very strongly with rounded profile and finely serrate margin, tiny median cleft, extending to a pigmented elongate trace, one pair of small tubercles between median cleft and, scattered small SS. Labial palp ( Fig. 4B–D ) 0.46 of length of prementum, outer margin with SPS and scattered SS from near its base to base of movable hook, inner margin with narrow flange transversely grooved and weakly crenate in distal 2/3; palpal lobe apically trifid; outer lobe moderately long smooth, uncinate tooth, middle lobe longer and thicker, terminally rounded weakly uncinate tooth; inner lobe securiform with tiny teeth; movable hook strong and short about 0.6 time as long as labial palp, tapered to acute apex, curving moderately inwards. Mandible ( Fig. 5A–E ) with mandibular formula: L 1+1’234 0 a(m 1,2)b / R 1+1’234 y a(m 0)b, asymmetrical, fattened, robust with well-developed long teeth on each incisor lobe, with molar crest; right mandible with 5 incisor teeth, molar crest with 2 teeth (a>b), with an additional tooth; left mandible with 5 incisor teeth, molar crest with small 2 teeth (a>1=2<b). Outer margin of mandible with 1 distinct spur on inner and two rows of strong spines arranging to form narrow oval with 12–15 spines, easily visible in dorsal and ventral view in the intact animal. Maxilla ( Fig. 5F–G ) galeolacinia with 7 teeth, 4 dorsal teeth of approximately the same size, apical teeth largest, 3 ventral teeth of small size.

Thorax: Two thirds breadth of head, with scattered CVS intermingled with SS. Prothorax saddle-shaped, anterior margin reaching postocular lobe, fitted into occipital margin of head; posterior margin rounded, with row of CVS; wing pads pale brown to dark brown, with a row of CVS from proximal to distal part, almost parallel, fore- and hindwing pads reaching base of middle of S5 and margins of S6 respectively. Legs broad, robust with femora especially broad and flattened, covered with dense SS, intermingled with SLS and CVS, forelegs with 2–4 small coxal spurs ( Fig. 6A ); tibial comb ( Fig. 6B–C ) with numerous SS intermingled with SLS and CVS in dorsal view, with numerous SS and row of SLS locating distal margin end in ventral view; tarsi with 2 rows of SS and scattered long simple setae, tarsal formula: 3-3-3; claws simple.

Abdomen: narrowing caudally, with pattern of each segment as in Figures 1 and 2 ; scattered SLS, intermingled with CVS and SS; abdominal terga, with a row of SLS and SS on posterior margin, abdominal terga S2–9 with a cluster of SLS intermingled with SS on the middle of posterior margin; abdominal pleura scattered SLS; abdominal sterna smooth, with a pale network of tracheoles, seven pairs of tapered abdominal gills on S2–8 becoming progressively shorter and more slender posteriorly ( Fig. 2B ), abdominal pleura S9 with row of SLS on distal margin. Male gonapophyses ( Fig. 7A ) very short, present on S9, paired, cone-shaped, with SS on ventral margin; not visible in lateral view, gonopore small, embossed O-shaped with central fissure; female gonapophyses ( Fig. 7B ) with two pairs of relatively short valves; lateral valves slightly arched, stout, with rounded tips, SS on venter; central valves smooth, slender, apically rounded; originating from base of sternite S9, extending only a little beyond posterior margin. Male cerci, ( Fig. 7C ) stout, blunt tip, curved, convergent, with scattered SLS and SS; female cerci ( Fig. 7D ) slender, blunt tip, concave ventrally with scattered long SLS and SS. Caudal gills ( Figs 1 , 2 , 8 ) large, saccoid, uniformly elongate with well-defined midrib then tapering to long gradually attenuated filament; everywhere with dense SS, posteriorly with sparse SLS and SS, distal half with dense long SS on ventral margin at middle. Median gill almost resembles lateral gills.

Measurements: (in mm; n = 9 (2 F-0, 5 F-1 alcohol preserved specimens and 2 exuviae)—Minimum–Maximum [mean]: total length of body without caudal gills = 12.72–20.58 [17.21]; length of caudal gills (median: lateral) = 6.81–7.56 [7.23]: 7.19–8.75 [7.77]; width and length of head = 4.04–6.72 [5.21] and 2.94–4.76 [3.74]; length of antenna = 2.64–4.17 [3.28]; maximum width and length of prementum = 2.65–3.55 [2.99] and 4.17–5.34 [4.57]; length of inner and outer wing pads = 2.18–7.17 [4.10] and 1.17–6.95 [3.78]; length of femora (fore: mid: hind) = 2.88–3.78 [3.31]: 3.03–3.76 [3.43]: 3.87–5.31 [4.80]; length of tibiae (fore: mid: hind) = 3.45–4.23 [3.92]: 3.21– 4.17 [3.73]: 3.59–4.56 [3.98].

Variation in F2 As F-0 and F-1, unless otherwise stated.

Labrum forming a rounded, entirely curve on central margin; median cleft forming short and small groove, without a pigmented extended trace. outer margins of postocular lobes bearing numerous tiny spines, not all aligned; fore- and hindwing pads inconspicuous, nestle with margin of synthorax; male gonapophysis vestigial; male cerci inconspicuous. Measurement (in mm; n = 1): total length of body without caudal gills = 11.47; width and length of head = 3.14 and 2.57; length of antenna = 2.02; maximum width and length of prementum = 2.10 and 2.54; length of femora (fore: mid: hind) = 2.29: 2.57: 3.42; length of tibiae (fore: mid: hind) = 1.14: 2.42: 2.85.

Habitat and biology

The larvae of D. gloriosa inhabit dense primary forests streams at elevation more than 650 m a.s.l. ( Fig. 9A–B ). The composition of the stream where collections were made was as follows: pebble/gravel/sand/silt (30%), small stones (40%), leaf litter (10%), aquatic plants (5%), large rocks (10%), and boulders (5%). The larvae were located under rocks and stones 15–35 cm diameter ( Fig. 9C ). They clung to the substrate, often upside down, under stones in pools or slow riffles ( Fig. 9D ) and sometimes were found together with larvae of the genus Euphaea Selys, 1840 . Exuviae, which, with hindsight were obviously of this species were previously found on large rock at Heaw Suwat in Khao Yai National Park.

Oviposition by adults was observed ( Fig. 9F ), male of D. gloriosa lead tandemed females to lay their eggs, descending under timber in swift water to oviposit. They perched midstream or streambank emergent dead timber in the manner of other known species ( Lieftinck 1959; Orr 2001; Yang & Orr 2024).

Figures

FIGURE 1. Larval habitus (F-0) of Dysphaea gloriosa, male.

FIGURE 2. Larval habitus (F-1) of Dysphaea gloriosa, female. (A), dorsal view; (B), ventral view.

FIGURE 3. Detail of antenna, head, frons, labrum, and genae of Dysphaea gloriosa. (A), right antenna; (B), frons and labrum, antero-dorsal view; (C), head, dorsal view; (D), right genae and postocular lobe, ventral view.

FIGURE 4. Detail of labium of Dysphaea gloriosa. (A), prementum and labial palps, dorsal view; (B), left labial palp, ventral view; (C), left palpal lobe, dorsal view; (D), left labial palp, lateral view.

FIGURE 5. Mandibles of Dysphaea gloriosa. (A–B, E) right mandible: (A), lateral view; (B), inner view; (E), ventral view; (C–D) left mandible: (C), inner view; (D), lateral view; (F), left galeolacinia, ventral view; (G), detail of left galeolacinia, internal view.

FIGURE 6. Prothorax (A), and distal part of leg (B–C) of Dysphaea gloriosa. (A), prothorax with procoxa, dorsal view; (B), foreleg, ventral view; (C), dorsal view.

FIGURE 7. Abdominal segments of Dysphaea gloriosa. (A, C) male: (A), ventral view; (C), posterior view; (B, D) female: (B), ventral view; (D), posterior view.

FIGURE 8. Caudal gills, dorsal view of Dysphaea gloriosa. (A), median gill; (B), lateral gill.

FIGURE 9. Larval habitat of Dysphaea gloriosa. (A), Kong Keaw Waterfall; (B), Heaw Suwat stream; (C), underside of rock to which D. gloriosa larva was clinging, green bracelet using for comparison size of the rock; (D), larva habitus of D. gloriosa photographed in the nature; (F), tandem pair of ovipositing D. gloriosa; the female will lay eggs in dead wood (Bhalee commune, Tay Giang District, Quang Nam Province, central Vietnam, taken in 28 April, 2018 by Q.T. Phan).