Enochrus (Methydrus) vulgaris Steinheil 1869
Creators: name: Byttebier, Barbara
name: Torres, Patricia L. M.
Publisher: name: Zenodo
Year: 2009
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Hydrophilidae
Enochrus
Enochrus vulgaris

description: Enochrus (Methydrus) vulgaris (Steinheil, 1869)
(Figs. 2, 7–10, 18–21, 24–25, 28–29, 31)
Material examined. ARGENTINA: Buenos Aires City: “Golf Club Lagos de Palermo”, 3 breeding adults collected on 02.xi.2006 by B. Byttebier. Buenos Aires City: Ecological Reserve “Costanera Sur”; 6 breeding adults collected on 02.xi.2006 by B. Byttebier (10 egg cases, 17 instar I, 5 instar II and 7 instar III larvae, 3 pupae, 5 emerged adults).
Diagnosis. Larvae. Coronal sulcus short (instar I) or very short (instar III); left mandible with one inner tooth; AN10 and AN11 subapically on the second antennomere; stipes with MX 4–6 distally on outer margin, located on a longitudinal row; PA26 closer to PA27 than to PA17; sterna III–VII with a pair of prolegs, each one bearing a group of cuticular spine strongly curved as hooks.
Egg case (Fig. 2). Total length = 4.34–6.75 mm, width = 1.91–2.36 mm; length without mast = 2.48–3.47; mast length = 1.86–4.09 mm.
Eggs, laid out without specific order pattern inside the egg case. (length = 0.52–0.67 mm, width = 0.27–0.35 mm). Number of eggs variable in each egg case, between 14 and 17 (N = 6).
First-instar larva (Figs. 7–10, 18). Morphometric measures detailed in Table 2.
Color. Head capsule dark brown. Antenna, mandible and labium light brown. Maxilla light brown with maxillary palpomere darker in some specimens. Thoracic tergites dark brown, thoracic appendages light brown; membranous areas of the thorax grayish brown. Abdominal sclerites, urogomphi and lateral appendages of abdominal segment VIII dark brown; membranous areas of the abdomen grayish brown.
Head capsule (Figs. 7–10). Coronal sulcus short. Mandible. Left mandible with one inner tooth.
Thorax. Prosternum composed by one undivided plate with a basal notch.
Abdomen. Sterna III–VII with a pair of prolegs, each proleg bearing a group of cuticular spine strongly curved as hooks (Fig. 31).
Chaetotaxy (Figs. 7–10, 18). Head capsule (Figs. 7–10). Ventral surface (Fig. 10) of each parietale, with sensilla PA26–PA28 located on a longitudinal row, very close to each other (PA26 closer to PA27 than to PA17). Antenna (Fig. 18). AN10 and AN11 situated subapically on outer margin of second antennomere.
Maxilla. Stipes with MX 4–6 located distally on outer margin, on a longitudinal row. Labium. LA2 located on the membranous area between submentum and mentum (Fig. 10); LA6 very long (1/3 longer than in E. variegatus). Legs. Ligula without apical processes. Chaetotaxy of legs summarized in Table 3.
Second-instar larva. Similar to first-instar larva except for the following features.
Morphometric measures detailed in Table 2.
Chaetotaxy. Head capsule. Parietale with 10–12 secondary sensilla: 3 setae and 1 pore close to PA8–PA9; 4–5 setae on the lateral margin; a row of 2–3 setae between PA6 and PA7. Mandible. With 5–7 secondary sensilla. Labium. Ligula without minute process apically (Fig. 24). Legs. Chaetotaxy summarized in Table 3.
Third-instar larva (Figs. 19–21, 24–25, 28–29, 31)
Similar to second-instar larva except for the following features.
Morphometric measures detailed in Table 2.
Head capsule (Fig. 21). Coronal sulcus short or very short, in general difficult to distinguish.
Thorax. Prosternum composed by one subdivided plate with an incomplete sagittal line on more than the basal third.
Chaetotaxy (Figs. 19–21, 24–25, 28–29). Head capsule. Each parietale with 9–11 secondary sensilla: 3 setae and 1 pore close to PA8–PA9; 4–5 setae on the lateral margin; a row of 1–3 setae between PA6 and PA7. Mandible (Figs. 19–20). With 7–8 secondary sensilla. Labium (Figs. 24–25). Each lateral margin of mentum with 4 stout secondary setae. Legs (Figs. 28–29). Chaetotaxy summarized in Table 3.
Pupa. Body. TL (excluding pronotal styli and cerci) = 3.25–4.40 mm; MW = 1.14–1.59 mm.
Head. Maxillary palpi extending to first abdominal segment.
Abdomen. Segment I with 2 pairs of styli situated on a transversal row.
description: Published as part of Byttebier, Barbara & Torres, Patricia L. M., 2009, Description of the preimaginal stages of Enochrus (Hugoscottia) variegatus (Steinheil, 1869) and E. (Methydrus) vulgaris (Steinheil, 1869) (Coleoptera: Hydrophilidae), with emphasis on larval morphometry and chaetotaxy, pp. 1-22 in Zootaxa 2139 on pages 13-16, DOI: 10.5281/zenodo.188528