Cordulegaster diadema Selys 1868
Creators: name: Novelo-Gutiérrez, Rodolfo
Publisher: name: Zenodo
Year: 2018
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Odonata
Cordulegastridae
Cordulegaster
Cordulegaster diadema

description: Larva of Cordulegaster diadema Selys, 1868
(Figs. 14–23)
Material studied. 11 F-0 larvae, 6 exuviae (IEXA), MEXICO: Estado de México; Presa Iturbide (19°31’44.30” N; 99°26’31.79” W), elevation 3152m, stream at coniferous forest, 18 June 1988, R. Arce leg., 1 F-0 larva ♂; Temascaltepec; Chilchotla (19°00’06.88” N; 100°02’00.22” W), elevation 1847m, stream in coniferous forest, 22 August 2004, R. Novelo, V. García leg., 1 F-0 larva ♂; Real de Arriba (19°02’07.21” N; 99°59’59.62” W), elevation 1931m, stream in coniferous forest, 21 April 2004, R. Novelo, V. García leg., 1 F-0 larva ♂; same data but 0 1 May 2008, R. Novelo, K. Cuevas leg., 1 F-0 larva ♂; Valle de Bravo, Avándaro, Parque Velo de Novia (19°09.776 N; 100°08.503 W), elevation 1907m stream in coniferous forest, 0 3 August 2008, R. Novelo, K. Cuevas leg., 1 F-0 larva ♀. Hidalgo; Zacualtipán, Tepeoco (20°41’04.25” N; 98°40’15.80” W), elevation 1800m, stream at pine forest, 19 May 1980, R. Novelo leg., 1 F-0 larva ♂; same data but 26 July 1986, R. Novelo, V.
García leg., 1 F-0 larva ♂. Michoacán; Uruapan, Toreo El Alto (19°27’19.49” N; 102°00’18.08” W), elevation 1783m, stream at coniferous forest, 0 7 June 1998, R. Novelo, V. García leg., 1 F-0 larva ♀; Los Azufres, 2.5 km NW of San Pedro Jácuaro (19°43’57.15” N; 100°39’32.80” W), elevation 2271m, stream at coniferous forest, 19 September 2003, R. Novelo, J.A. Gómez leg., 2 exuviae ♂, ♀, 1 F-0 larva ♂, emerged on 21 September 2003 at 06:05 a.m. Morelos; Tetela del Volcán (18°54’09.94” N; 98°42’25.09 W), elevation 2217m, stream at coniferous forest, 8 November 1986, R. Novelo, V. García leg., 1 exuvia ♀. Querétaro; Pinal de Amoles, Chuveje (21°10’10.4” N; 99°33’28.7” W), elevation 1313m, Arroyo Chuveje (El Tigre), 14 May 2014, D. Reynoso leg., 1 F-0 larva ♂. Veracruz; Coatepec, Río Huehueyapan (19°27.151 N, 96°58.881 W), elevation 1196m, stream at cloud forest, 27 March 2001, R. Novelo leg., 1 F-0 larva ♀, emerged on 18 October 2001 at 08:43 a.m.; same data but 8 September 2003, R. Novelo leg., 1♂ emerging at 14:30 h; Río Ahuacatlán (19°28’19.90” N; 96°59’04.65” W), elevation 1369m, stream at cloud forest, 31 May 2001, R. Novelo, J.A.Gómez leg., 1♀.
Redescription. Larva large (45 mm length) and robust, body hairy and tapering caudally, large labial palps, legs relatively short, caudal appendages sharply pointed, and coloration yellow to reddish-brown or dark brown.
Head (Fig. 14). Wider than long, covered mainly with scale-like setae, and long, stout, stiff setae on posterior margin of occipital lobes. Labrum with long and short stiff setae, a dense brush of long, delicate setae along the anterior border, which is widely concave at middle and not flattened ventrally. Anteclypeus bare, postclypeus mostly bare with long, white, delicate setae on sides of anterior and lateral borders; frons moderately produced in a widely convex frontal shelf, anterior margin beset with a row of long, stout, stiff setae, and scale-like setae on anterior half of dorsal surface. Antennae short and 7-segmented, scape and pedicel cylindrical, third antennomere the longest, size proportions: 0.5, 0.6, 1.0, 0.4, 0.5, 0.6, 0.7. Compound eyes small, protruding dorsally. Occiput large and bulging laterally, with lateral and lateroposterior margins covered with short and long, stout, stiff setae; dorsal surface with scale-like setae. Mandibles (Figs. 15–16) with formula: L 1234 0 a(m1,2,3,4,5)b / R 1234 y a(m1,2,3,4,5,6 or 7,8)b, a>b, the molar crest high, m denticles small, blunt, semi-fused forming a continuous ridge. Maxilla’s galeolacinia with seven teeth, three dorsal teeth slightly incurved, similar length and robustness, four ventral teeth of different size (Fig. 17). Ventral pad of hypopharynx transversally enlarged, subrectangular, with abundant long setae mainly on the lateral margins, and a row of stout, stiff setae along posterior margin directed apically (Fig. 17). Labium: prementum-postmentum articulation almost reaches anterior margin of metacoxae. Prementum subtriangular (Fig. 18), lateral margins widely divergent with spiniform setae which increase in size apically continuing to the base of palp articulation; apical half of dorsal surface with abundant minute setae; large premental setae usually 4, occasionally 5¯6, additional smaller setae 3¯8 on each side of midline; ligula well developed, a paired median median process on apical margin, split by V-shaped incision, a dense row of short, piliform setae on apical border excepting median process (Fig. 18); median process slightly serrulate on basal half of lateral margins sometimes ending in a short spine (Fig. 19), tips widely divergent. Labial palpi strongly developed (Fig. 18), covering anterior part of head as a mask; apical lobes divided into 10¯11 long, sharply pointed hooks of different size and robustness (Fig. 19), and one internal rounded lobe, all of which are finely serrulate on margins; dorsal margin of palp with rows of short, stiff setae (Fig. 18), external surface with abundant, small spiniform setae (Fig. 19); movable hook slender, sharply pointed and smooth; 5 palpal setae (Fig. 18). Ventral surface of prementum covered with delicate, long, white setae, a longitudinal, bare, central sulcus on basal 0.40 of ventral surface (Fig. 20).
Thorax. Prothorax with a large, transversal pronotal disc beset with long, stiff, white setae on rounded lateral margins (Fig. 14), anterior margin slightly concave, posterior margin strongly convex at middle. Prothorax and synthorax covered densely by minute reddish setae, lateral surface and inferior margins strongly setose; mes- and metepisterna with a large brown band, remainder of synthorax yellowish. Legs hairy and relatively short (hind legs barely reaching posterior margin of S7 when fully extended); internal (posterior) margin of prothoracic tibiae moderately sinuate; all legs light brown, no dark bands or rings present; pretarsal claws simple with pulvilliform empodium. Wing pads light brown with borders yellow, anterior wing pads moderately divergent, posterior wing pads subparallel; anterior and posterior wing pads reaching basal half and posterior margin of S4, respectively.
Abdomen. Cylindrical, reaching its maximum width on S5, strongly tapering caudally, yellow on S1, and yellow with a complex pattern of dark spots on S2–10 (Fig. 21). All tergites covered with small, yellow brown setae, and long, fine, white setae on sides. Posterior margins of S2–9 with a row of long, white, fine setae, and scattered stout stiff setae; posterior margin of S10 with short spiniform setae intermingled with small delicate setae. Dorsal protuberances and lateral spines lacking. Sterna 1–2 creamy pale, 3¯9 yellowish-brown, 10 reddish-brown with abundant reddish setae on surface, posterior margins of sterna 1–7 and 10 with a row of golden delicate setae conspicuously shorter and stout on 8–9; sterna 2–8 divided into three sternites, sternum of 9 consisting of one sternite, that of 10 forming a continuous ring with respective tergum. Male gonapophyses lacking, female gonapophyses well developed, ventral gonapophyses the largest, roundly pointed, convergent apically, almost reaching posterior margin of sternum 9 (Fig. 22). Epiproct and paraprocts acutely pointed with tips long, reddish, and curved downwards near tip (Fig. 23), yellow to reddish-brown, pyramidal, same length, with abundant long setae on borders, and a row of large stout spiniform setae on lateral surface of paraprocts (Fig. 23). Male epiproct with a large, subquadrate, mound-like tubercle on middle at basal 0.22 (Fig. 21). Cerci conical, strongly tapering at apical 0.30 in male (Fig. 23), tips slightly convergent (Fig. 21), 0.25 as long as paraprocts.
Measurements (in mm): Larvae (in alcohol, N=11) [mean in brackets]: TL, 39–51.5 [44.5]; AL (ventral, incl. app) 27.5–36.5 [31.6]; MWh, 8.6–10.3 [9.3]; HfL (lateral), 6.5–8.1 [7.9]. Exuviae (in alcohol, N=6): TL, 46–49.5 [47.6]; AL, 29–35 [32]; MWh, 8.8–10 [9.4]; HfL, 7–7.7 [7.3].
Remarks. Needham’s (1904) brief description of the supposed larva of C. diadema fits well with the larvae of C. diadema I reared; however, Needham provided only a small drawing of the median process of the ligula. The most frequent morphological variation I found was in the number of premental setae, in both the primary and secondary series. Also, the presence of a spine at the end of the serrulate median process is highly variable. Larvae usually occupy sand and silt banks in slow moving waters, frequently in pools behind large rocks or boulders near the edges of streams in mountainous areas. Larvae of C. diadema are probably partivoltine as has been recorded in other species such as Cordulegaster dorsalis Hagen in Selys, 1858 (Kennedy 1917; Marczak et al. 2006).
description: Published as part of Novelo-Gutiérrez, Rodolfo, 2018, Cordulegaster virginiae sp. nov. from Mexico, including a comparison with C. diadema Selys, 1868, and a redescription of its larva (Odonata: Cordulegastridae), pp. 371-382 in Zootaxa 4394 (3) on pages 378-382, DOI: 10.11646/zootaxa.4394.3.3, http://zenodo.org/record/1199784