Orthemis ferruginea (Fabricius, 1775)

Carrillo-Lara, Diana E. & Novelo-Gutiérrez, Rodolfo, 2018, Description of the larva of Orthemis ferruginea (Fabricius, 1775) (Odonata: Libellulidae), Zootaxa 4455 (3), pp. 547-554 : 548-550

Orthemis ferruginea (Fabricius, 1775)

( Figs. 1–5 )

Material studied: 4 exuviae (1♂, 3♀♀, reared from eggs), 5 F-0 larvae (2♂♂, 3♀♀). MEXICO: Veracruz; Municipality of Paso de Ovejas, El Angostillo (19°12.916 N; 96°32.370 W), elevation 244m, pond at dry forest, 15 February 2016, D. Carrillo, R. Novelo leg.

Description. Larvae and exuviae dark brown dorsally ( Fig. 1a ), pale ventrally ( Fig. 1b ), body robust and hairy, legs hairy, caudal appendages long and sharply pointed.

Head ( Fig. 2a ). Subrectangular, 1.4 times as wide as long, wider than thorax. Labrum brown, 1.0 mm long, moderately granulose, anterior margin setose. Clypeus pale, anteclypeus bare, postclypeus with a transverse row of small setae; anterior surface of frons pale, bare, anterior border with abundant, very long, whitish setae directed forwardly, dorsal surface with short, dark, stiff and erect setae; vertex blackish-brown, with a tuft of long, dark brown setae, ocelli pale. Antenna 7-segmented, scape and pedicel cylindrical, scape mostly brown, pedicel and flagellomeres yellow ( Fig. 2a ), scape and pedicel with short, brown stiff setae, flagellomeres with sparse, short and long delicate setae, third antennomere the longest, scape and 4th antennomere the shortest, size proportions: 0.5, 0.6, 1.0, 0.5, 0.7, 0.7, 0.7. Compound eyes relatively small, protruding dorsally ( Fig. 2b ). Occiput large, with 11 oval, vertical, parallel, glabrous areas bordered and separated from each other by abundant, short, dark brown setae ( Fig. 2a ). Mandibles ( Fig. 2c, d ) without molar crest, with formula: L 1234 0 a b / R 123+ 4 x y a b d, b>d>a. Maxilla: Galeolacinia ( Fig. 2e ) with seven teeth, three dorsal teeth almost straight, of similar length but basal one more slender, four ventral teeth of different size and robustness, basal tooth shortest, apical one largest, maxillary palp a little longer than galeolacinia, ending in a robust blunt spine. Ventral pad of hypopharynx transversally enlarged ( Fig. 2f ), subrectangular, with abundant long setae on anterior margin, a row of stiff setae along posterior margin directed apically. Labium spoon-shaped; prementum-postmentum articulation reaching posterior margin of procoxae. Prementum subrhomboidal ( Figs. 3a, b ), 1.2 times as wide as long, lateral margins widely divergent apically with a subbasal, short row of small setae; large premental setae ( Fig. 3a ) 3–4, usually 4, additional smaller spiniform setae 7¯9 on each side of midline; a row of 13–15 short setae at the base of palp articulation; ligula moderately developed, anterior margin strongly crenate ( Figs. 2b , 3a ), crenations usually 22–23, central crenation largest, extended into the dorsal surface of ligula as a swollen area, a minute spiniform seta between each crenation ( Fig. 3a ). Labial palpi strongly developed, covering inferior part of face as a mask ( Fig. 2b ), each with 8–9 strong crenations on apical margin, internally each crenation with 3 claviform setae; 7–8 (usually 8) palpal setae on dorsal margin ( Fig. 3a ), internal margin almost straight with 7–8 regularly spaced spiniform setae; external surface of palp dotted, internal surface with a group of 12–13 minute spiniform setae close to palp’s base; movable hook short and slender, shorter than most of palpal setae, sharply pointed and smooth. Ventral surface of prementum ( Fig. 3b ) covered with sparse delicate setae, no central sulcus visible on ventral surface.

Thorax. Prothorax with a transversally enlarged, light brown pronotum ( Figs. 1a , 2a ); anterior margin of pronotal disc straight, posterior margin convex, lateral margin rounded, all margins beset with short, dark brown, stout setae; a large, subrectangular bare area on each side of midline ( Fig. 2a ); inferior margin of propleura with tufts of long, white setae. Mesospiracle well exposed ( Figs. 1a , 2a ), with its internal and external ends subequally raised. Side of pterothorax sloping down more or less steeply ( Fig. 1a ), dorsal border and most of lateral surface with abundant, short, stout dark setae; inferior margins of meso- and metathorax with long, white setae. Legs setose ( Figs. 1a , 2a ), coxae, trochanters and tarsi yellow, femora and tibiae dark brown; external (anterior) surface of tibiae with a comb of large, dark, stiff setae ( Fig. 2a ); internal (posterior) surface of protibia ( Fig. 4a ) with an internal row of tridentate setae, and an external row of large, stout, yellow setae, and with large spiniform setae at apex; internal surface of meso- and metatibia only with the row of large, stout, yellow setae ( Fig. 4b ); ventral surface of all tarsi with two rows of setae as follows: protarsomeres ( Fig. 4c ) with an internal row of tridentate setae, the external one with stout spiniform setae on basal and middle tarsomeres, and hair-like setae on distal tarsomere; ventral surface of basal and middle mesotarsomeres with strong spiniform setae in both rows ( Fig. 4d ), distal mesotarsomere with an internal row of tridentate setae and an external row of hair-like setae; all metatarsomeres ( Fig. 4e ) with an internal row of tridentate setae and an external row of stout spiniform setae; pretarsal claws simple with pulvilliform empodium. Anterior and posterior wing pads slightly divergent ( Fig. 1a ), reaching basal half and posterior margin of S5, respectively, both pairs setose mainly on borders.

Abdomen. Enlarged, fusiform ( Figs. 1 , 5a ), reaching its maximum width at S5–6, gradually tapering caudad, with S10 reduced and sunken into S9, S1–5 pale, S6–10 dark brown ( Figs. 1a , 5a ). Tergites 1–4 mostly bare, 5–9 with abundant, short, dark setae ( Fig. 5a ), posterior margins of S6–10 with a row of small spiniform setae; no dorsal protuberances at all, only a subapical, middorsal tuft of long, reddish-brown, bristle-like setae on S2–9 ( Fig. 5a ); lateral margins of S1–9 with abundant, long, delicate white setae, intermingled with a row of small spiniform setae on S2–10; lateral spines on S8–9 short and sharply pointed ( Fig. 5a ), those of S8 more or less parallel, those of S9 moderately incurved and longer, 0.15-0.3 and 0.4-0.5 the middorsal length of their respective segments. Sterna 1–7 creamy pale to grayish yellow, 8 yellowish-brown, 9 reddish-brown, 10 dark brown ( Fig. 1b ); posterior margins of sterna 1–6 with long, delicate setae, 7–10 with a row of spiniform setae which increase in size and robustness caudally; sternum 9 with a subapical tuft of long, white setae on each side of midline; sternum 5 divided into five sternites, sterna 2–4 and 6–9 divided into three sternites, that of 10 forming a continuous ring with respective tergum; sutures parallel on 2–4, slightly convergent caudally on 5–7, slightly divergent on 8–9. Gonapophyses lacking. Caudal appendages ( Figs. 5a, b ) pyramidal, long, sharply pointed, basal half dark brown, apical half yellow. Epiproct and paraprocts of same length, cerci 0.40 the length of epi- and paraprocts; epiproct with a row of spiniform setae intermingled with long, bristle-like setae on ventral border; cercus with a row of small spiniform setae on external surface of apical third; paraproct with a row of stout spiniform setae intermingled with bristle-like setae on dorsal and ventral borders.

Measurements: Larvae (in alcohol, N=5) [mean in brackets]: TL, 22–25 [23.3]; AL (ventral, incl. app) 13.5–

15 [14.4]; MWh, 4.9–5 [4.96]; HfL (lateral), 4.7–5 [4.86]; Ep and Pp, 2.2–2.5 [2.38]; Ce, 0.8–1 [0.94]. Remarks. The most frequent morphological variation we found was in the number of premental setae, in both the primary and secondary series. Also, but in a lesser extent, the number of palpal setae varied, even in the palps of the same specimen, which is common in larvae of Libellulidae (2nd author, pers. obs.). Larvae usually inhabit the muddy bottom of lentic habitats such as ponds and temporary pools. We collected F-0 larvae in a highly eutrophized pond with a water temperature of 40°C close to the surface, and 35°C at 15cm depth in the muddy bottom, around 1400 h in a sunny day.

Figures

FIGURES 1. Details of the morphology of the F-0 larva of Orthemis ferruginea. 1) Habitus dorsal, a; habitus ventral, b.

FIGURES 2. Details of the morphology of the F-0 larva of Orthemis ferruginea. Head and prothorax, dorsal view, a; head and prementum, frontal view, b; right mandible, internal view, c; left mandible, ventrointernal view, d; left galeolacinia, ventral view, e; ventral view of maxilla and hypopharynx, f.

FIGURES 3. Details of the morphology of the F-0 larva of Orthemis ferruginea. 3) Prementum, dorsal view, a, ventral view, b.

FIGURES 4. Details of the morphology of the F-0 larva of Orthemis ferruginea. 4) Protibia, laterointernal view, a; mesotibia, internal view, b; protarsi, ventral view, c; mesotarsi, ventral view, d; metatarsi, lateroventral view, e.

FIGURES 5. Details of the morphology of the F-0 larva of Orthemis ferruginea. 5) Abdominal S5-10 and caudal appendages, dorsal view, a; S7-10 and caudal appendages, left lateral view, b.