Neoelmis argentinensis, Manzo & Archangelsky, 2012

Manzo, V. & Archangelsky, M., 2012, Two new species of Elmidae (Coleoptera) from Argentina, Zootaxa 3478, pp. 267-281 : 275

Neoelmis argentinensis sp. nov., mature larva

( Figs 7–25)

Length: last instar length 6.1 to 6.9 mm; maximum width 0.6 to 0.7 mm. Body elongate ( Figs 7–8), parallel sided, subcylindrical in cross-section; color brown to reddish brown.

Head capsule: Subquadrate, prognathous, not concealed by pronotum; surface covered by granules, smaller on basal 1/5 ( Fig. 9). Ocular areas light brown, stemmata closely aggregated forming an ocular-spot. Coronal suture short, frontal sutures long, extending to base of antennae on anterolateral corners of head capsule; frontoclypeal suture weakly insinuate. Anterior margin of clypeus serrate, with small tooth on each lateral margin close to antennal base ( Fig. 10). Gula well demarcated, subtrapezoidal, basal margin wider than distal ( Fig. 16).

Labrum: Subrectangular, with anterolateral corners rounded ( Figs. 11–12); midline with transverse row of setae, anterolateral corners with four strong setae each. Ventral surface of labrum (epipharynx) pubescent ( Fig. 12).

Antenna: Short, as long as mandible, with 3 antennomeres ( Fig. 13). Basal antennomere stout, with several distal setae and pores, inner margin with short cuticular spines; second antennomere longest, bearing a slender apical sensorium on outer margin; third antennomere shortest, slightly shorter than sensorium, bearing short distal seta.

Mandibles: Symmetrical, grooved, apex tridentate ( Figs 14–15), with one distal tooth and two subapical teeth, one dorsal and one ventral; an additional small inner retinaculum on dorsal margin. Inner margin of groove with comb of setae projecting medially. Dorsal inner margin with long setose articulated process projecting medially (prostheca); outer margin of mandible with two stout, hyaline ramose setae.

Maxilla: Cardo short, subtriangular ( Fig. 16), bearing one fringed seta. Stipes long, subrectangular ( Fig. 16), bearing several small fringed setae on basal third and outer margin; one long and stout subapical seta on outer margin and one large pore mediad of that seta. Lacinia and galea well developed ( Fig. 17); lacinia with a strong lobe with five strong setae on mesal margin, projecting dorsally; galea one-segmented, with serrated distal margin and 4 apical setae. Palp with 4 palpomeres ( Fig. 17), first palpomere shortest, with one outer branched seta; remaining palpomeres subequal in length, second palpomere with two ventral pores, third palpomere with two ventral pores and two short dorsal apical setae; fourth palpomere the narrowest, with several distal sensilla.

Labium: Large, formed by prementum and postmentum ( Fig. 17). Postmentum large, subrectangular, longer than wide, basal third with several short fringed setae; distal third with one stout long seta on each outer margin and one pair of large pores close to midline; lateroapical margins each with a long, blunt, articulated porose sensillum. Prementum short, subtrapezoidal, less sclerotized, each anterolateral corner with a fringed seta. Palpi with two palpomeres ( Fig. 17), palpomeres subequal in length, basal one stouter, with one ventral apical pore and several cuticular spines on outer and distal margins; second palpomere with several short sensilla. Ligula as a short lobe, bearing a transverse row of short setae and covered by numerous short, cuticular spines.

Thorax: Strongly sclerotized, all sclerites covered by setiferous tubercles densely distributed, those on dorsal and lateral areas conical ( Fig. 18), those on ventral areas shorter and distally concave ( Fig. 19); tergal plates with sagittal lines. Prothorax as long as meso- and metathorax combined (ca. 0.65 mm, Figs. 7–8), subquadrate in dorsal view; anterior margin of pronotum with row of tubercles bearing long feather-like setae; venter of prothorax with five sclerites ( Fig. 20): two anterior, subrectangular, two lateral and one posteromedial, subpentagonal; procoxal cavities closed. Meso- and metathorax shorter, subequal in length, wider than long, subrectangular in dorsal view. Venter of meso- and metathorax each with five sclerites ( Fig. 21), one large, subpentagonal, anterior to coxae, two small ones on each lateral margin; coxal cavities open; mesothorax with one pair of lateroventral spiracles. Legs similar in shape ( Fig. 22), those of prothorax shortest. Coxa large, subtriangular; trochanter small, subtriangular; femur long, wider distally; tibia long, narrower than femur, bearing hooked tarsungulus.

Abdomen: Long, tapering towards distal end, nine-segmented; segments I-VIII subequal in length, slightly wider basally than distally. Terga I-VIII with sagittal line ( Fig. 7). Pleural sclerites present on segments I-VII ( Fig. 24); sternal sclerites of these segments subquadrate ( Fig. 24); sternum of segment I with a short carina on anterior third ( Fig. 23). Segment VIII entire, ring-like. Segment IX elongate, 2.5 times longer than previous segment, bearing a feeble dorsal keel ( Fig. 7); sternal area with apical gill chamber, operculum subpentagonal, covering a pair of strong distal hooks ( Fig. 25). Spiracles present laterally on segments I-VIII.