Hexatoma (Eriocera) fuliginosa (Osten Sacken, 1860)

Podeniene, Virginija & Gelhaus, Jon K., 2015, Review of the last instar larvae and pupae of Hexatoma (Eriocera) and Hexatoma (Hexatoma) (Diptera, Limoniidae, Limnophilinae), Zootaxa 4021 (1), pp. 93-118 : 99-101

Hexatoma (Eriocera) fuliginosa (Osten Sacken, 1860)

( Figs. 10–20 )

Diagnosis. Larval and pupal characters as in genus and: larva with maxillary palps 2X as long as mandible; spiracular lobes slender, marginal hair on lateral and ventral spiracular lobes of unequal length, ventral hairs much longer; apex of ventral lobes with a few extended darker setae, length 3– 4 X length of lobe. Ventral spiracular lobes with thin dark median line apically, bifurcating into “Y”-shaped pattern proximally, lines not meeting medially. Mature larva medium sized, length about 20 mm. Pupa yellowish brown with dark wing pads. Pupa with respiratory horns slightly divergent, apex rounded. Cephalic crest with two horns. Antennal sheath short in both sexes.

Description. Length of last instar larvae— 19–21 mm; width—2.5–3.0 mm. Body covered with long brown hairs, giving body golden brownish color. First and anterior part of tenth body segment with longer hairs forming longitudinal rows. Posterior part of tenth segment with shorter hairs forming short irregular transverse rows ( Fig. 10 ). First and second thoracic and 2nd–8th abdominal segments wider than longer. Last thoracic and the first abdominal segments very short. Small structures similar to spiracles on tergum of every segment. Last abdominal segment (anal) constricted, with very long and dense setae, especially on outer surface of spiracular lobes. Penultimate segment distinctly inflated. Four long stout setae on posterior end of sternite of penultimate segment, 1–2 and 3–4 setae very close to each other. Area of longer hairs between second and third setae ( Fig. 11 ).

Head capsule — 2.1–2.3 mm long, 0.9–1.0 mm wide. Overall structure similar to that of H (E.) californica except: one long seta on the anterior part of labrum ( Fig. 12 ); third tooth of mandible blunt and much smaller than the second one ( Fig. 13 ); basal segment of antennae four times as long as wide at base, apically with three long setae ( Fig. 14 ).

Last Segment: Spiracular field surrounded by four flattened elongate lobes ( Fig. 15 ). Dorsal lobe vestigial. Ventral lobe 1.5 times as long as lateral lobe. Lateral lobe almost 2.5 times as long as wide at base. Ventral lobe almost three times as long as wide at the base. Apical part of lateral and ventral lobe fringed with dark brown long hairs, almost as long as lobe itself. Apex of ventral lobe bears few darker and longer setae, 3–4 times as long as lobe ( Fig. 15, 16 ). Outer margin of lateral lobe and vestigial dorsal lobe fringed with short hairs. Lateral lobe with very narrow line (sclerite) on inner margin of lobe, slightly widened at base. Ventral lobe with very narrow line distally (sclerite), bifurcated and distinctly widened at base forming an overall “Y” pattern. Outer margin of ventral sclerite darker than inner. Spiracles small, circular, widely separated by 4X diameters of a spiracle. Inner circle of spiracle dark brown, outer ring light brown.

Anus surrounded by four long, white, fleshy anal papillae ( Fig. 11 ). Papillae lobes almost cone-shaped, equal in size. Three long setae at the base of each ventral pair and tuft of very long setae at the base of lateral pair ( Fig. 16 ).

Pupa. Male pupa 18 mm long, 2.9 mm wide. Female pupa 20 mm long, 3 mm wide. Abdomen yellowish brown. Head, thorax, wings and tergites of abdominal segments second and third dark brown, much darker than the rest of the body. Head: cephalic crest prominent, with wrinkled surface and four unequal lobes ( Figs. 17, 19 ). Posterior (dorsal) lobes large, each trapezoid shaped with four long setae ( Figs. 18, 20 ). Anterior pair of lobes much smaller than posterior pair, horn-shaped with single long seta near base. Antennal sheaths in both sexes short, only slightly extending beyond base of wing ( Figs. 17, 19 ). Tubercle on antennal scape prominent in male, much smaller in female. Two prominent tubercles on posterior part of clypeus. Labrum trapezoidal with bluntly rounded apex. Labial lobe diamond-shaped. Maxillary palp broad, transversal with small tubercles. Thorax: respiratory horns 0.8 mm long and 0.15 mm wide in both sexes, less than half of head width; minute annulations along entire length of horn; apex slightly flattened and rounded; at base light brown, rest dark brown. Dorsum of thorax smooth with short longitudinal rows of spines near base of wing in both sexes ( Fig. 17, 19 ). Apex of wing almost reaching the end of second abdominal segment in both sexes ( Figs. 17, 19 ). Two long setae at base of wing. Legs reaching almost two thirds length of third abdominal segment in male and half length of third abdominal segment in female, hind pair slightly longer than other pairs. Abdomen: segments II–VII with very well defined annuli ( Figs. 18, 20 ), dividing each abdominal segment into two parts; anterior part narrower than posterior (length of both parts is similar), except segment VII. Tergites and sternites on posterior part with transverse rows of small tubercles with spines. Some tubercles with seta instead of spine. Transverse rows of tubercles of second and third tergites interrupted in the middle ( Figs. 18, 20 ). Number of spines on dorsum and venter varies, usually more than 50 on each (except segment VII) segment. Sternites of segments II–III with two additional tubercles with two setae almost in the middle of posterior ring (at the level of spiracles). Sternite of segment VII with two short transverse rows of spines interrupted by broad area ( Figs. 18, 20 ). Prominent spiracles almost in the middle of pleurites of abdominal segments III–VII. Two to three setae near dorsal margin of abdominal spiracles. Small tubercle with single seta in middle of anterior part of segments III–VII. Terminal segment of male blunt, narrow. Ventral lobes (anal spines) well developed, short with rounded tips directed dorsally, reach base of posterotergal spines ( Fig. 17 ). Posterotergal spines sharp pointed, directed upward with two setae in middle of length. Anterodorsal and mediodorsal spines small; similar in shape and size with few setae on tips, situated almost in middle of tergum of terminal segment ( Fig. 18 ). Small tubercle with long seta near anterodorsal spine. Prominent tubercle with two long setae situated on pleurite. Two prominent tubercles with four setae on middle of sternite of terminal segment. Terminal segment of female elongate ( Fig. 19 ). Sheaths of cerci much longer than valves, directed upward with few setae on apex ( Fig. 19 ). Posterotergal spine single, more prominent than paired mediodorsal and anterodorsal spines ( Fig. 20 ). A small tubercle with long seta near anterodorsal spine. Small tubercle with long seta situated on pleurite. Small tubercle with two long setae situated on middle of sternite.

Specimens examined. 4 last instar larvae, 1 female pupa and 2 male pupae from USA: New Jersey: Burlington Co., Mt. Misery Brook, Mt. Misery area 6.5 km E of junction Hwys. 70 & 72; 39°55’11”N, 37°31’24”W, elevation 38 m, 2.VII. 1993, collected by J. K. Gelhaus and M. Livingston.

Habitat. Exposed sand bar at creek edge.

Figures

FIGURES 10 – 16. Hexatoma (Eriocera) fuliginosa. 10. General view of last instar larva, lateral aspect. 11. Posterior end of penultimate segment and terminal segment, ventral aspect. 12. Labrum and clypeus, dorsal view. 13. Right mandible, dorsal view. 14. Right antenna, dorsal view. 15. Spiracular field. 16. Penultimate segment and terminal segment, lateral aspect.

FIGURES 17 – 20. Hexatoma (Eriocera) fuliginosa. 17. General view of male pupa, lateral aspect. 18. General view of male pupa, dorsal aspect. 19. General view of female pupa, lateral aspect. 20. General view of female pupa, dorsal aspect.