Morphology, Surface Structure and Sensory Receptors of Larvae of Cueta lineosa (Rambur 1842) (Neuroptera: Myrmeleontidae)

Sadreddin Tusun*

Dicle University, Ziya Gökalp Education Faculty, Biology Department, 21280, Diyarbakır, Turkey.

ABSTRACT

The morphology of larvae of Cueta lineosa (Rambur 1842) is described and figured for the first time by scanning electron microscopy (SEM). The females were collected from Batman, Diyarbakır and Mardin Provinces in South Eastern Anatolian Region of Turkey and maintained in the laboratory. The different parts of the third instar larvae such as antennae, head, mandibles, abdomen and types of sensory receptors are described and illustrated.

Article Information

Received 12 June 2018

Revised 22 August 2018

Accepted 20 April 2019

Available online 06 November 2019

Key words

Neuroptera, Sensory receptors, Larvae, Scanning electron microscope (SEM), Turkey

DOI: https://dx.doi.org/10.17582/journal.pjz/2020.52.1.331.335

* Corresponding author: [email protected]

0030-9923/2020/0001-0331 $ 9.00/0

Copyright 2020 Zoological Society of Pakistan

Abbreviations

An, antenna; cl, ­­claw; dbrst, digging bristle; f, flagellomere; lp, labial palp; md, mandible; p, palpomeres; s, sternite; sbs, sensilla basiconica; sc, sensillum chaeticum; sco, sensilla coeloconica; smt, submedian tooth; sp, spiracle; stm, stemmata; str, sensilla trichodea; ta, tarsus; to1, toot1; to2, tooth2; to3, tooth 3.

Introduction

The order Neuroptera (lacewings) comprises 19 families, and Myrmeleontidae (antlions) are the largest family of the order, with about 2000 species distributed throughout the world. Whilst adult antlions are generally nocturnal, resting on plants during the day, the larvae have adopted a variety of predation strategies (Mansell, 1996, 1999). A few antlion larval species build distinctive cone-shaped pits in sandy soil that are used to trap ground dwelling invertebrates, particularly ants (Mansell, 1996). Larval morphological characters have played an important role in the taxonomy of Myrmeleontidae. There are some studies on larvae morphology of Myrmeleontidae (Devetak et al., 2010a, b; Badano and Pantaleoni, 2014). Up to now, few studies on larval characters and sensory receptors with SEM have been made (Satar et al., 2006, 2014a, b; Nicoli Aldini, 2007; Cesaroni et al., 2010 Devetak et al., 2010a, b, 2013), but the studies of larvae of antlions are still insufficient. The third stage larva of C. lineosa has been described by Mirmoayedi (2002). However, larval features were not described in detail and there were no clear photographs of corresponding larval characters and sensory receptors. Badano and Panteleoni (2014) made a detailed study on the morphology of the C. lineosa with lack of the charecters illustrated by the SEM. Until now, the morphology of larvae of C. lineosa have not been described comprehensively by SEM. In this paper the larvae are described and illustrated in detail by use of light and scanning electron microscopes.

Material and methods

The gravid females of C. lineosa (Fig. 1a) were collected from Batman, Diyarbakır and Mardin Provinces in South Eastern Anatolian Region of Turkey, using nets or light traps between 2014 and 2017. Females were individually isolated in glass boxes of 10x5x5 cm. They laid 3-6 eggs on the bottom of box. Larvae were placed in glass boxes that were filled with soil brought from the localities where the gravid females were collected. The larvae were kept in laboratory at a room temperature. They were fed an assortment of insects such as ants and whitefly (Chrysoperla carnea) (Sattar, 2017).. Observations and study were made with an Olympus SZX7 Stereomicroscope and photographed with an Olympus Digital Camera mounted on it. Third instar larvae were examined and measured with a Quanta 250 FEG scanning electron microscope (SEM).

Results

The larvae of C. lineosa complete their life cycle in one or two years depending on the abundance of food. The duration of each stage for this species is as follows: from egg to newly hatched larva 15-25 days; second-instar larva 25-40 days; third-instar larva 10-12 months; pupa

15-25 days. These numbers are based on a sample of 20 larvae.

Third instar larva of C. lineosa (Figs. 1b and 1c): Body color light brown, covered with long setae and clavate dolichasters. Size (based on 12 specimens): Body length 5.5-6.5 mm (without mandibles), width (widest part) 4.5 mm (3.9-4.6). Head: longer than wide; with v-shaped; length 2.75 mm (2.7-2.86); width at widest part 1.40 mm (1.3-1.6); dark brown, covered with black hairs and clavate dolichasters on dorsal surface (Fig. 1d). Surface of prothorax fine granular and with clavate dolichasters. Eyes black, with seven stemmata. Six of which are close together and at the top while the other is below and slightly further away (Figs. 1d, 1f). Mandibles longer than head capsule width. Mandible 1.9 (1.9-2.1) mm long, Mandibles black-brown with three teeth, the tooth 2 is the longest and in contact with tooth 3. Tooth 3 is the shortest one (Figs. 1f and 1g). Shape of teeth look like in M. trigrammus (Devetak et al., 2013). Surface mandibles and maxillae bear a great number of sensilla coeloconica as Figures 1f, 1g, 1i and Fig 2a; eight long black bristles between base of the mandible and first tooth; three to four black bristles between first and second tooth, only one bristle between second and third tooth or no bristles there, but no bristle between the third tooth and pointed end of mandible (Figs 1f, 1g). Labial palpus with distal four palpomeres. On their distal segment occur sensilla basiconica as in Figures 2b, 2c and 2d. Each antenna with 11 flagellar segments and on the distal part of the last flagellomere a group of three sensilla basiconica are found (Figs. 2e and 2f). Pronotum small, sclerotized, convex, roughly elliptical and nearly as broad as long, bearing tubercules, no scoli. Lateral margins of each thoracic and abdominal segment (except prothorax and terminal segments 9 and 10 of abdomen) prolonged into a pair of scoli, ten pairs in all. Thoracic spiracles very large (Fig. 2f); all other spiracles smaller, ventro-laterally located, one pair for each of the first eight abdominal segments. Abdomen broad, pale brown with white dolichasters and with sensilla (see for an abdominal sensillum trichodeum Figure 2g). Sternite 8 with two small submedian teeth (Fig. 2h). For digging bristles see. Legs: tarsi of fore and mid legs covered with longitudinally grooved bristles. The tip of the tarsus of all legs has two claws. Between the claws, two short sensilla trichodea occur (Fig. 2i).

Discussion

The genus Cueta comprises at least 80 known species distributed in the arid areas of Eurasia and Africa (Stange, 2004). The larvae are known only for a handful of species (Willmann, 1977; Stange et al., 2003; Krivokhatsky, 2011). Larvae form ball-like cocoons, construct pitfall traps, such as species of the genera Myrmecaelurus.

Up to now several larval morphology of the Palearctic antlion taxa has been described by the using of SEM: Myrmeleon formicarius Linnaeus (Eisenbeis and Wichard, 1987), Distoleon tetragrammicus (Fabricius)

(Satar et al. 2006), Myrmeleon inconspicuus Rambur (Nicoli-Aldini, 2007), Myrmeleon bore (Tjeder) (Nicoli-Aldini, 2007), Macronemurus bilineatus and Megistopus flavicornis (Suludere et al., 2009), Myrmeleon mariaemathildae (Pantaleoni et al., 2010), Myrmeleon yemenicus Hölzel (Devetak et al., 2010b), Neuroleon microstenus (McLachlan) (Devetak et al., 2010), Gymnocnemia variegata (Schneider) (Cesaroni et al., 2010), Megistopus flavicornis (Rossi) (Cesaroni et al., 2010), Myrmecaelurus trigrammus (Pallas, 1771) (Devetak et al., 2013), Gepus gibbosus Hölzel, 1968 (Satar et al., 2014a), Solter ledereri Navas, 1912 (Satar et al., 2014b), Tricholeon relictus (Hölzel and Monserrat, 2002) and Nemoleon notatus (Rambur, 1842) (Badano et al., 2017).

Larvae of C. lineosa have non-prominent eye tubercles and numerous bristles on the jaws, which are both characteristic for pit-builders, like Myrmeleon species (Eisenbeis and Wichard, 1987; Nicoli Aldini, 2007; Devetak et al., 2013).

Mandibles of C. lineosa longer than head capsule while in Myrmecaelurus trigrammus (Pallas, 1771) length of mandibles equal to head capsule (Devetak et al., 2013). Labial palps are four-segmented and on their distal segment one on the tip, the other subterminally two groups of sensilla basiconica occur. With these features C. lineosa is same as Myrmecaelurus trigrammus (Pallas, 1771) (Devetak et al., 2013).

Each eye tubercle in C. lineosa larvae bears seven stemmata. In the eyes of all larval antlion species studied so far (Jockusch, 1967; Eisenbeis and Wichard, 1987; Nicoli-Aldini, 2007; Satar et al., 2006; Cesaroni et al., 2010; Pantaleoni et al., 2010; Devetak et al., 2010a,b, 2013; Satar et al., 2014a, b) an eye tubercle bears seven stemmata. Six of them are on the dorsal anterior part of the tubercle, and the seventh one oriented ventrally.

On the abdominal tip of C. lineosa two groups of digging bristles are arranged in the same way as in Distoleon tetragrammicus (Satar et al., 2006) and Myrmecaelurus trigrammus (Pallas, 1771) (Devetak et al., 2013) and in a similar pattern as in Neuroleon species (Steffan, 1975; Devetak et al., 2010a) and Cueta beieri (Hölzel, 1969; Badano and Pantaleoni, 2014).

The number of the teeth (three teeth) on the inside of the jaw is general feature of antlions specimens. Shape of teeth look like in Myrmecaelurus trigrammus (Pallas, 1771) (Devetak et al., 2013) and Cueta beieri U(Hölzel, 1969; Badano and Pantaleoni, 2014). In C. lineosa eight long black bristles between mandibular base and tooth 1, and three to four bristles between tooth 1 and 2 and one or none bristle between tooth 2 and 3 are appear. There are no bristles between the third tooth and pointed end of the mandible. The bristles are respectively eight to nine (rarely seven), two to four, none and none in Myrmecaelurus trigrammus (Pallas, 1771) (Devetak et al., 2013).

conclusion

The larval morphology of C. Lineosa has been described in details using scanning electron microscope (SEM).

Acknowledgements

The author especially thank Prof. Dr. Ali Satar of Dicle University, Diyarbakır, Turkey for providing insightful comments to improve the manuscript.

Statement of conflict of interest

The authors declare no conflict of interest.

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