Nilio (Linio) lanatus Germar, 1824

Simões, Marianna V. P., Quintino, Hingrid Y. S. & Monné, Marcela L., 2009, Larva and pupa of Nilio (Linio) lanatus Germar, 1824 (Coleoptera: Tenebrionidae), Zootaxa 2175, pp. 51-56 : 52-56

Nilio (Linio) lanatus Germar, 1824

( Figs. 1–19 )

Nilio lanatus Germar, 1824: 161 ; Guérin-Méneville 1844: 122; Thomson 1860: 12; Ihering 1914: 299; Blackwelder 1945: 503; Watt 1974: 426, fig. 78; Gil-Santana & Marques 2008: 272. Nilio (Linio) lanatus: Mader 1936: 95 .

Nilio paralanatum Ihering, 1914: 290 ; Mader 1936: 95.

Diagnostic characters of larva. Body elongate. Head and prothorax orangish; mesonotum, metanotum, and tergites dark brown to black; mesosternum, metasternum, legs, and abdominal sterna whitish to brown. Dorsal region with very dense, erect, long (white) and short (black) setae. Head with four stemmata. Mesothorax with one pair of ventral annular spiracles.

Description of larva (last instar). Length 7.4 mm, maximum width 3.6 mm.

Body elongate, moderately convex. Integument slightly sclerotized; head and prothorax orangish; mesonotum, metanotum, and tergites dark brown to black; mesosternum, metasternum, legs, and abdominal sterna whitish to brown. Dorsal region with very dense, erect, long (white) and short (black) setae.

Head ( Figs. 1–2 ) hypognathous, half width of prothorax, rounded laterally and with short, black, dense setae. Epicranial stem long, frontal arms U-shaped. Four small stemmata present, three arranged in a semicircular row near antennal insertion, and one widely separated stemmatum, near ventral region.

Antennae 3-segmented, short, almost lateral and dorsally directed; antennomeres I and III annular, short and transverse; II cylindrical, 6 times longer than I.

Clypeus trapezoidal with distal area membranous; two setae near each lateral margin. Labrum ( Fig. 5 ) transverse, with sparse, moderately long setae, two long setae near each lateral margin and a row of short setae on the apical margin. Epipharynx ( Fig. 6 ) with short dense setae directed medially. Gular sutures short. Gula transverse. Mandibles ( Figs. 7–10 ) robust, asymmetrical, with three teeth; lateral margin with setae near base; mola well developed, rounded, and more elongate on left mandible. Maxilla ( Fig. 3 ) elongate; cardo transverse; stipes elongate and with three long setae near palpifer and smaller, sparse setae near lateral margin; mala elongate with rounded apices and with dense short setae on the outer margin. Palpifer visible. Maxillary palpi with three palpomeres, gradually shorter and narrower toward apices, last palpomere rounded. Labium ( Fig. 4 ) elongate; labial palpi with two palpomeres; proximal palpomere robust, distal palpomere smaller and narrower; prementum elongate, rounded at sides and with sparse setae; postmentum elongate, rectangular with dense, long and short setae. Ligula membranous, elongated, with rounded apices and short setae.

Prothorax slightly shorter than following thoracic segments combined; anterior margin rounded. Mesothorax with one pair of ventral annular spiracles ( Fig. 14 ). Legs well separated, 5-segmented, slender, subequal in length and with sparse, long and short setae; coxa elongate; trochanter subtriangular; femur slightly longer than tibia; tarsungulus without setae.

Abdomen 10-segmented. Segments 1–8 transverse, similar, gradually narrowing to the apices and with one pair of dorsolateral annular spiracles on each segment. Segment 9 very short, without urogomphi; segment 10 reduced, distal, and bilobate at apex.

Description of pupa ( Figs. 15–18 ). Length 6.2 mm, maximum width 5.5 mm.

Ventral region brownish, dorsal region orangish to dark brown; thorax with yellowish dorsomedian line; elytra with irregular orangish spots. Dorsal region with dense short dark-brown setae and long whitish hairs. Head invisible from above; pronotum transverse, projected at sides. Abdominal segments 1–5 with one pair of halteriform projections at sides.

The pupa remains inside the last larval cuticle ( Figs. 17–18 ), covering the last abdominal segments.

Remarks. The larvae of the described species of Nilioninae are very similar in general aspect, and differ mainly by the pattern of coloration of the body and pilosity. Costa et al. (1988) redescribed the larva and pupa of Nilio (L.) varius , and in this species the larval body is distinctly large and the mesothoracic spiracles are elliptical. In Nilio (L.) lanatus the larval body is elongate and the mesothoracic spiracles are annular ( Fig. 14 ). According to Gil-Santana & Marques (2008), Nilio (Micronilio) barthi has only three stemmata arranged in a semicircular row near antennal insertion; Nilio (L.) lanatus has three, corresponding stemmata arranged in a semicircular row, but a fourth small stemmatum is present, widely separated, near the ventral region.

Specimens examined. BRAZIL. Rio de Janeiro: Itatiaia (Parque Nacional do Itatiaia) 1100 m, 16.XI.2007, 2 mature larvae, 3 pupae, 4 adults, Miguel A. Monné & Marcela L. Monné leg. (MNRJ).

Biological notes. The observations were made in Atlantic Forest, in the Parque Nacional do Itatiaia, Rio de Janeiro ( Brasil). Five larvae and 15 pupae of Nilio (Linio) lanatus were observed ( Fig. 19 ) on a tree trunk, possibly indicating a gregarious habit. Two larvae and three pupae were collected and fixed in 70% ethanol. One larva and three pupae were collected and kept alive in the laboratory; the larva was observed to scrape the surface of the branch and fix itself in the rugosities of the bark, by means of the tarsungulus of the three pairs of legs. After the ecdysis, part of the pupa remains inside the last larval exuvium ( Fig. 17–18 ), and this explains how the pupae can remain fixed on a vertical trunk ( Fig. 19 ). The duration of the pupal stage was nine days.

Similar biological observations were made by Ihering (1914) with Nilio (Nilio) brunneus, Jorge (1974) with Nilio (Linio) varius , and Gil-Santana & Marques (2008) with Nilio (Micronilio) barthi . All these species are gregarious and feed on fungi on the surface of branches, and part of the pupa remains inside the last larval exuvium. The pupal stage of N. (L.) varius lasted 7 days.

Figures

FIGURES 1 – 10. Larva of Nilio (Linio) lanatus Germar, 1824. 1, head, dorsal view; 2, head, ventral view; 3, maxilla; 4, labium; 5, labrum; 6, epipharynx; 7 – 10, mandibles, 7 – 8 left, dorsal and ventral view; 9 – 10 right, dorsal and ventral view. Scale bars, 1 mm.

FIGURES 11 – 14. Larva of Nilio (Linio) lanatus Germar, 1824. 11, dorsal view; 12, ventral view; 13, lateral view; 14, enlarged view of the mesothorax spiracle.

FIGURES 15 – 19. Nilio (Linio) lanatus Germar, 1824. 15, pupa, dorsal view; 16, pupa, ventral view; 17, pupa with the last larval exuvium, lateral view; 18, last larval exuvium and pupa exuvium; 19, larvae and pupae alive on a tree trunk.