Tetragonoderus variegatus Dejean, 1829

Santos, Guilherme Ide Marques Dos, 2015, Description of the larva of Tetragonoderus (Crossonychus) variegatus Dejean, 1829 (Coleoptera: Carabidae: Cyclosomini) with notes on biology, Zootaxa 3973 (1), pp. 102-118 : 104-105

Tetragonoderus variegatus Dejean, 1829

Late instar larva ( Figs 10, 11 , 18–23 ).

Description. Body length (from mandible to urogomphi apex, macrosetae excluded): 9.8mm.

Body form ( Figs 10–11 , 18–20 ): very slender, subparallel-sided.

Color: whitish yellow with testaceous head and prothorax.

Vestiture ( Figs 10, 11 , 16–18 ): slightly sclerotized.

Cephalic capsule ( Figs 21–23 ): as long as wide (length / width ratio = 0.91); rounded sides; wider in the posterior third, slightly narrower at the base; flattened; more depressed in the frons area towards nasale; nasale suture (fontoclypeal) present. Adnasale slightly pointed toward sides with two setae; nasale subtriangular, bilobed at the apex, each lobe pointed bearing a very short seta, one seta on each side of the nasale area, two pores between the lobes and the suture, ventrally with short setae and two tufts of long pectinate setae reaching the apex of prementum; frons with four setae close to the nasale suture (two in the middle and two setae and one pore on the sides); small round depression next to the frontal sutures intersection and two larger L-shaped depressions in the middle with setae 2 and 3 at the anterior margin, one pore posteriorly. Stemmata composed of two pairs of three oblong convex lenses on each side; dark pigment spread throughout the stemmata area. Ocular groove present, but not clearly visible in alcohol ( Figs 21, 23 ). Cervical groove absent. Epicranial suture length / head length (base to nasale apex) ratio = 0.17. Frontal sutures clearly visible, deeply curved and sinuous. Lateral carina from the base of mandible to the third basal, with five long aristate setae dorsally.

Antenna (like Figs 26, 27 ): four articles; first article with two ventral pores close to the apex, and three ventrally: one close to the apex, one central and one close to the inner margin, apically with a small concentration of ventral microtrichae close to the external margin; second article shorter, as long as wide, without seta and pores; third article with three long setae (two in the middle, more proximal than the sensorium and one very long, longer than the article, at the apex), two small sensilla and one small pore around the sensorium, one short dorsal seta close to the apex and the external margin, and one dorsal pore on the proximal third in the middle; fourth article narrower with three long and two short setae, and one pore near the apex.

Mandible: falciform; broad base, moderately curved; with two setae on the proximal third of the external margin, most proximal seta shorter [one specimen with two setae in the proximal socket in the left mandible]; 2 pores on the middle (one anterior and one posterior to the retinaculum); penicillus well developed, reaching the curved retinaculum; terebra smooth.

Maxilla: lacinia indistinct. Cardo with one ventral seta. Stipes with 7 setae: one spiniform on the external margin close to the apex, two thick setae proximally to the spiniform, one very long and thin between them (almost as long as stipes), one long and one shorter more distally than the gMX on the inner margin and one very small and thin close to the apex; gMx with variable number of dense thin setae; and three pores ventrally. Galea with two articles (half as long as maxillary palps), both almost same length; first article of galea with one ventral seta on the proximal third, and one pore apically; second article glabrous with two apical membranous sensilla. Maxillary palps with four articles; first article is the shortest, with 1 spiniform seta on the external margin; second article is the longest with 2 pores on the apical third; third article with one pore on the apical third and fourth article with two pores and two apical membranous sensilla.

Labium (like Figs 31, 32 ): labial palps with two articles, each bearing one pore, second article with a group of sensilla at the apex. Prementum subquadrate, as long as wide, dorsally with a longitudinal broad line of microtrichae and four setae, the proximal seta much shorter, four setae dorsally, the proximal pair in the middle near the lateral margins and the distal pair near the apex; ligula short but distinct, with one long apical seta; each side of the base of hypopharynx with a long tuft of long setae reaching the half of the first palpomere.

Legs: increasing in length from the front to the hind legs. Segments flattened. Coxa globose, more robust than the other segments, bearing three long setae along the outer line, the most distal thicker; a spiniform seta located ventrally on the inner surface in the middle and a short next to the apex with a pore anteriorly; one short seta near the base dorsally and one short near midline. Dorsally with three short setae near to the base and two long ones (one on the middle and one on the distal third) followed by a row of microtrichiae to the apex. Trochanter transverse, subtriangular, with two pairs of spiniform setae longitudinally arranged ventrally near the apex, one very long and one short setae next to the posterior pair; one short and one thin seta at the second half ventrally and one dorsally next to the base; five pores on the inner and two in the outer surface. Femur transversally connected to trochanter with a short seta next to the base, dorsally; ventrally with four to six setae with variable thickness and size and five spiniform setae around the apex (sometimes also with one small short seta). One pore on the inner surface at middle of the first third and one at midline of outer surface. Tibia shorter and narrower than femur, longer than half femur length, one thin long seta next to the base dorsally and six spiniform setae around the apex. Tarsus longer and thinner than tibia, with six thick setae around the apex, one broader than the others. Tarsal claws straight, almost the same length as the tarsus, thinner toward the slightly curved apex.

Thorax: pronotum subrectangular, longer than wide, anterior (anterodiscal area) and posterior (posterodiscal area) margins with narrow membranous band patterned with rugose longitudinal lines composed of small pores, anterior margin expanded on the fore angles; parallel sides; six setae on the lateral margins, the most anterior and most posterior shorter; each half bearing an oblique longitudinal line of three setae on the lateral third, and one posterior and one anterior seta on the central half; proepipleurite with two setae; one seta on each side of the procoxa condile. Mesonotum subquadrate, wider than longer, anteriorly with a dark line and a membranous narrow band patterned with a rugose longitudinal lines; each half with seven setae on the lateral half (six on the anterior half and one on the posterior half), and two on the central half (one anterior near the center and one next to the midline); mesoepipleurite shorter than half of mesonotum length, bearing three setae; rounded spiracle on the sides, between epipleurite and tergite, anteriorly, bigger than abdominal spiracles; one seta on each side of the mesocoxa condile. Metathorax similar to mesothorax, but with a small epipleurite bearing a single seta replaces the spiracle.

Abdomen: segments I–VII subrectangular, wider than long, getting slightly longer from I to VII; segment VIII subtrapezoidal; dorsal side of I–VIII bearing four setae anteriorly and four setae posteriorly each; center glabrous; segment VIII with one additional seta on each side posteriorly near the midline; epipleurites with four setae; hypopleurite with six setae (two anterior and four posterior); ventral sclerites not clearly evident, with five setae on each side, round spiracle on the sides between epipleurite and tergite, anteriorly; segment IX subtrapezoidal, very narrow posteriorly, dorsally with about 16 setae, epipleurite with five setae, sternite with six setae; urogomphus with two extensions, slightly longer than the pygidium, unarticulated, with superficial appearance of having four segments, but the cuticle is continuous throughout, each extension with about 10–14 setae, three of them at the apex. Pygidium cylindrical, each half with five setae laterally, four setae ventrally, and two dorsally.

First instar larva ( Figs 9 , 24–38 )

Description. Characters as in later instar except for the following:

Body length (from mandible to urogomphi apex, macrosetae excluded) ( Fig. 9 ): about 4.0mm.

Color ( Fig. 9 ): lighter colored.

Vestiture ( Fig. 9 ): less sclerotized.

Cephalic capsule ( Figs 24, 25 ): two small digitiform egg-buster on each side of the frons, close to the frontal suture, obliquely positioned; only three setae along the lateral line, dorsal depressions of the head less pronounced.

Mandible ( Figs 28, 29 ): just one seta on the external margin, between the base and the retinaculum line; terebra with a short serrate area next to the retinaculum.

Maxilla ( Fig. 30 ): external margin of the stipes with just the apical spiniform and the very long setae.

Legs ( Figs 33, 34 ): coxa with just one dorsal long seta without the row of microtrichia anteriorly; femur without the ventral seta and only four spiniform setae around the apex (sometimes with an extra short one); tibia with only five spiniform setae around the apex.

Thorax ( Figs 35, 36 ): lateral margins of the pronotum without the two median setae

Abdomen ( Figs 37, 38 ): less setae on the segment IX, only 6 long setae on each urogomphus extension (three at the apex, two lateral and one dorsal close to extension base) and less setae on pygidium.

Examined material. BRAZIL, Santa Catarina: Florianópolis, Caieira da Barra do Sul beach, adults collected from 28.XII.2013 – 04.I.2014, larvae obtained in the laboratory on II–III. 2014, 7 ex. All material is currently housed in the MZSP.

Figures

FIGURES 4 – 11. Collection localities: 4 View of Caieira da Barra do Sul Beach (collection locality) 5 View of Caieira da Barra do Sul Beach 6 Dunes of Santinho Beach (collection locality); Rearing box: 7 Lateral view 8 Interior view; Tetragonoderus

FIGURES 18 – 19. Tetragonoderus variegatus larva, later instar. 18 Dorsal view 19 Ventral view.

FIGURES 20 – 23. Tetragonoderus variegatus, later instar larva. 20 Lateral view; Head: 21 Dorsal view 22 Ventral view 23 Lateral view.

FIGURES 12 – 16. Molting Tetragonoderus variegatus larva: 12 Dorsal view 13 Ventral view 14 Lateral view 15 Head, lateral view 16 Head, dorsal view.

FIGURE 17. Lighting system used for photography of dead specimens, dome diameter = 12 cm.

FIGURES 26 – 32. Tetragonoderus variegatus, first instar, chaetotaxy 26 Left antenna, first segment, ventral view 27 Left antenna, dorsal view 28 Right mandible, dorsal view 29 Left mandible, ventral view 30 Left maxilla, ventral view 31 Labium, ventral view 32 Labium, dorsal view.

FIGURES 24 – 25. Tetragonoderus variegatus, first instar, cephalic capsule, chaetotaxy. 24 Dorsal view 25 Ventral view.

FIGURES 33 – 38. Tetragonoderus variegatus, first instar, chaetotaxy. 33 Midleg, inner view 34 Midleg, outer view 35 Pronotum 36 Mesonotum 37 Segment IX, dorsal view 38 Segment IX (part) and X, lateral view.