Larvae of Cueta Sauteri (Esben-Petersen) and Myrmeleon Bore (Tjeder) (Neuroptera, Myrmeleontidae): Description and Behavioral Notes
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Zootaxa 3734 (3): 362–370 ISSN 1175-5326 (print edition) www.mapress.com/zootaxa/ Article ZOOTAXA Copyright © 2013 Magnolia Press ISSN 1175-5334 (online edition) http://dx.doi.org/10.11646/zootaxa.3734.3.5 http://zoobank.org/urn:lsid:zoobank.org:pub:8A03C32B-A799-474C-A97B-69AEFAAC8217 Larvae of Cueta sauteri (Esben-Petersen) and Myrmeleon bore (Tjeder) (Neuroptera, Myrmeleontidae): description and behavioral notes JIE ZHANG1, XUBO ZHANG1 & XINLI WANG1 Department of Entomology, China Agricultural University, Beijing 100193, China. E-mail:[email protected] Abstract Antlion larvae of Cueta sauteri (Esben-Petersen) and Myrmeleon bore (Tjeder) from mainland China were collected in the field and reared to adults in the laboratory. Larval morphology of each species was described and complemented with behavioral observations. Their most important diagnostic characteristics are head capsule markings, mandibular length, mandibular teeth length, distance between mandibular teeth, bristle number between the distal mandibular tooth and apex of the mandible, morphology of labial palpi and antennae, peduncle of mesothoracic spiracle and the arrangement of digging bristles. Larvae of these two species construct similar conical pits and wait for prey at the bottom of the traps. Key words: Larval morphology, antlion, pit building behavior, mainland China Introduction The family Myrmeleontidae (Neuroptera) comprises 1,522 species recorded worldwide (Stange 2004). Larval morphological characters have played an important role in the taxonomy of Myrmeleontidae. Stange (2004) lists ten larval keys for Myrmeleontidae (one key to tribes and nine keys to genera). But the study of larvae of antlions is still insufficient, as most species of antlions lack a detailed description of their larvae. Cueta comprises 77 known species (Stange 2004) distributed in Africa and Eurasia. Three species have been found in China: C. lineosa (Rambur, 1842), C. plexiformia Krivokhatsky, 1996, and C. sauteri (Esben-Petersen, 1913). Previously, the larvae of C. sauteri from Taiwan have been briefly accounted for by Stange et al. (2003). However, larval features were not described in detail and there were no clear photographs of corresponding larval characters. Myrmeleon, as the largest genus of Myrmeleontidae, comprises 177 known species and it is widely distributed in the world. Nineteen species have been recorded from China, including seven species collected from Taiwan. The larvae of six Taiwanese species, M. alticola Miller & Stange, M. heppneri Miller & Stange, M. persimilis Miller & Stange, M. punctinervis Banks, M. taiwanensis Miller & Stange, and M. wangi Miller & Stange, have been briefly described (Stange et al. 2003). Wang and Li (2011) described the larvae of M. ferrugineipennis Bao et Wang, 2009 and M. trivialis Gerstaecker, 1885 collected from Guizhou, China. At present, the larval morphology of M. bore (Tjeder, 1941) from mainland China has not been comprehensively described. Larval morphology of M. bore from Europe and Japan has been described by several authors. The head capsule markings and labial palpi of M. bore from north-Europe and Japan have been depicted (Friheden 1973; Matsura 1987b). Nicoli Aldini (2007) described the larval morphology of M. bore collected in northern Italy. He provided scanned electronic micrographs of several characteristics, but no color photos were available. Krivokhatsky (2011) provided the photos of head and labial palpi. However, details of mandibular teeth, the bristle between distal mandibular tooth and apex of the mandible, the details of antennae, peduncle of mesothoracic spiracle and digging bristles of M. bore larvae were not described. The life cycle, foraging behavior, construction of the pits, oviposition and behavioral response to starvation of M. bore larvae have been reported (Matsura 1987a; Gepp 1989; Matsura et al. 1991; Matsura & Murao 1994; Matsura et al. 2001; Matsura 2003). Because of the limited information on Cueta sauteri and the fact that the morphological characters of 362 Accepted by A. Contreras-Ramos: 14 Oct. 2013; published: 6 Nov. 2013 Myrmeleon bore needed to be complemented, we provide a comparative description of the third instar larvae of these two species. Behavioral habits of both species were recorded, as we attempt to emphasize the relevance between the morphological characters and their function. Examined specimens were collected from Hebei Province and Hainan Province of China. Material and methods Larvae of C. sauteri and M. bore were collected from mainland China and reared in the laboratory. Feeding. Larvae of the various instars were placed in plastic bowls (with a diameter of 115 mm and a height of 75 mm) filled with sand from the collecting places. The larvae were reared in the laboratory at room temperature (16°C – 24°C). Larvae of the first or second instar were fed with fruit flies twice a day. Larvae of the third instar were fed with mealworms once in three days. Some larvae were raised to adults that were later identified. Eight larval specimens in the third instar were deposited in 70% alcohol. Each specimen examined was given a database number corresponding to an ICCAU (Insect Collection of the China Agricultural University, Beijing, China) collection code entry. Larvae were observed under a stereoscopic microscope. Photographs of morphological traits were taken using a digital camera (Canon® EOS 500D) which was connected to a microscope (Olympus® U-CTR30-2) and UV-C (Application Suite) applied software by United Vision Ltd. These original photos were processed using Adobe Photoshop® CS6. Morphological description of third instar larvae Cueta sauteri (Esben-Petersen, 1913) (Figs. 1, 2) Size: body length (including mandibles) 15.0–16.0 mm, body width (widest part) 5.7 –6.0 mm, head length (without mandibles) 1.8–1.9 mm, head width (widest part) 1.9–2.0 mm, length of the mandibles 2.0–2.1 mm. Head: yellowish brown. Head capsule approximately square, posterior margin of the head arc-shaped. The dorsal side of head capsule with numerous bristles, a pair of oblique dark stripes near posterior margin, another pair of oblique dark stripes in anterior part (Fig. 5). Ventral side of head bare, with a pair of oblique convergent dark brown stripes near anterior margin, close to each other posteriorly and far separated anteriorly (Fig. 6). Mandible yellowish brown and dark brown at the apex. Mandibular teeth yellowish brown with dark brown apex. Mandibular length almost equal to the length of head capsule, with three teeth; distal tooth shorter than middle tooth; distance between tooth 1 and 2 longer than distance between tooth 2 and 3; mandible without bristles between the third tooth and apex of the mandible, 1 bristle between tooth 3 and 2, 2–3 bristles between tooth 2 and 1; setae on external margin of mandible shorter than mandibular greatest width (Fig. 7). Antennae filiform, long and slender (Fig. 15). Ocular tubercles prominent, dark brown, consists of seven dark brown or black stemmata, six stemmata on the dorsal side of ocellar tubercle and one on the ventral side (Figs. 15, 16). No bristle is among stemmata. Labial palpi pale, longer than basal width of mandible, four segmented, the third article slightly longer than the second (Fig. 11). Thorax: trapezoid, prothorax is the narrowest segment. Tergites yellowish brown with scarce dark spots and sparse bristles, sternites yellowish white (Fig. 19). Dorsal side of thorax without punctum; lateral scoli no distinctly prominent, with tufts of bristles; mesothoracic spiracle with elongated peduncles (Figs. 17, 19). Abdomen: 10-segmented, the 10th segment invaginated. Tergites yellowish brown and sternum yellow white. No evident lateral scoli; each segment with a dorsal pair of dark brown to black spots, ventral side yellow to white with some black spots (Figs. 1, 2); sternite VIII with a pair of conspicuous brown teeth and some stout setae at posterior margin (Fig. 20); sternite IX with two rows of lateral long bristles (anterior row 6 bristles, posterior row 6 bristles), coniform digging bristles in 4 rows (2, 2, 2, 8) (Figs. 20, 21). Examined material. 3 larvae, Ledong, Hainan Province, China (18° 45’ N, 109° 10’ E), XI. 2007, Zhi-Liang Wang (CAU0015–CAU0017). All the specimens were deposited in ICCAU. STUDY ON LARVAE OF TWO ANTLION SPECIES Zootaxa 3734 (3) © 2013 Magnolia Press · 363 FIGURES 1–2, 5–7. Third instar larva of Cueta sauteri. 1. Dorsal view. 2. Ventral view. 5. Head, dorsal view. 6. Head, ventral view. 7. Mandible, dorsal view. FIGURES 3–4, 8–10. Third instar larva of Myrmeleon bore. 3. Dorsal view. 4. Ventral view. 8. Head, dorsal view. 9. Head, ventral view. 10. Mandible, dorsal view. 364 · Zootaxa 3734 (3) © 2013 Magnolia Press ZHANG ET AL. Myrmeleon bore (Tjeder, 1941) (Figs. 3, 4) Size: body length (including mandibles) 14.5–15.0 mm, body width (widest part) 4.8–5.0 mm, head length (without mandibles) 2.0–2.1 mm, head width (widest part) 1.8–1.9 mm, length of the mandibles 2.5–2.6 mm. Head: dark brown from dorsal view and yellow brown from ventral view. Head capsule is approximately oval with numerous bristles. Two pairs of oblique dark stripes on posterior part and 3 black spots near anterior margin from dorsal view (Fig. 8); ventral side of head capsule with two dark brown stripes near each other anteriorly and far separated posteriorly (Fig. 9). Mandible yellowish brown and dark brown at apex. Mandibular teeth yellowish brown with dark brown apex. Mandibular length longer than head capsule length, with three teeth; tooth 3 longer than 2; all teeth usually equidistant; 1–2 bristles between the third tooth and apex of mandible, 2–3 bristles between tooth 2 and 3; the longest setae on exterior margin of mandible longer than mandibular greatest width (Fig. 10). Antennae filiform, long and slender (Fig. 13). Ocular tubercle black, consisiting of 7 dark stemmata (Figs. 13, 14). Some bristles are among stemmata. Labial palpi shorter than basal width of mandible, three segments, the third segment darker (Fig.