Myrmeleon bimaculatus Yang, 1999

Lin, Yu-Hsiu, Liao, Jhih-Rong & Ko, Chiun-Cheng, 2021, Fig. 5 in Periclimenaeus karantina Park & De Grave 2021, sp. nov., Zoological Studies 60 (39), pp. 1-24 : 7-9

Myrmeleon bimaculatus Yang, 1999 ( Figs. 3C , 4C , 7 , 8)

The larvae of M. bimaculatus are described here for the first time, and the species is reported in Taiwan for the first time. An image of the adult is also provided ( Fig. 8).

Description of 3rd instar larva: Size: Average body length 8.06 mm (6.71–9.13); head length 1.78 mm (1.72–1.84), head width 1.49 mm (1.40–1.59), mandible length 1.85 mm (1.73–1.99), ratio head width/length 0.84, ratio mandible length/head length 1.04.

General coloring: Pale ochre, with dark brown body markings.

Head: Sub-rectangular, longer than wide. Covered with short, black setae, ventral side with a setae-less medial line. Ocular tubercle sessile. Mandibles pale brown with apex reddish, slightly longer than the head capsule, provided with 3 equidistant teeth with the apical tooth slightly stronger. Interdental mandibular setae: (5–6)(2–3)(2–3)(1). Clypeo-labrum with pointed setae. External margin of the mandible with a fringe of long setae, dorsal side of the mandible with a sparse covering of short setae, ventral side of the mandible with a few setae at base. Labial palpus 4-articulated, with fringe of black setae underneath, not extending over labial palpus. Dorsal side of the head capsule with a dark brown spot on the clypeo-labrum, a pair of brown stripes on the anterior side, followed by a pair of dark brown spots, a pair of pale brown markings near the middle of the head, and a pair of small black markings on the posterior side. Lateral side of the head with a dark brown spot near the middle and a dark brown spot on the posterior side. Ventral side of the head with a pair of brown outwardly curved markings in the middle, occasionally broken into separated spots.

Thorax: Pronotum with a pair of brown stripes, covered with short setae. Body setae black.

Legs: Pale brown, unspotted.

Abdomen. Setae black, with pale brown setae on the ventral side. VIII abdominal sternite with a pair of dark brown spots, odontoid processes distinct, posterior margin with hair-like setae. IX abdominal sternite with a median row of 4 peg-like digging setae divided into 2 groups. Rastra sessile, each bearing 3 peg-like digging setae similar in size, 1 seta on the external side.

Materials examined: Taiwan. Hsinchu County. Hengshan St. Wood Factory, Hengshan Township / 26. XI. 2019 / J. W. Chuang leg., 1 L3, 2 L3 laboratory reared to adult. Kinmen County. Qilinshan Forest Park, Lieyu Township / 03. IX. 2020 / Y. H. Lin leg., 1 L3, 2 L3 laboratory reared to adult. Zhaishan, Jinchen Township / 03. IX. 2020 / Y. H. Lin leg., 1 L3 laboratory reared to adult. Miaoli County. Shangrila Paradise Amusement Park, Zaoqiao Township / 06. VIII. 2017 / Y. J. Tsao leg., 1 L3 laboratory reared to adult; same locality / 23. IX. 2017 / Y. J. Tsao leg., 2 L3 laboratory reared to adult; same locality / 01. IV. 2018 / Y. J. Tsao leg., 2 L3 laboratory reared to adult; same locality / 05. V. 2018 / Y. J. Tsao leg., 2 L3 laboratory reared to adult; same locality / 07. VII. 2018 / Y. J. Tsao leg., 5 L3 laboratory reared to adult; same locality / 04. VIII. 2018 / Y. J. Tsao leg., 5 L3 laboratory reared to adult; same locality / 01. IX. 2018 / Y. J. Tsao leg., 3 L3 laboratory reared to adult; same locality / 06. X. 2018 / Y. J. Tsao leg., 5 L3 laboratory reared to adult; same locality / 04. XI. 2018 / Y. J. Tsao leg., 1 L3, 10 L3 laboratory reared to adult; same locality / 01. XII. 2018 / Y. J. Tsao and Y. H. Lin leg., 13 L3 laboratory reared to adult; same locality / 12. I. 2019 / Y. J. Tsao leg., 4 L3 laboratory reared to adult; same locality / 17. III. 2019 / Y. H. Lin leg., 1 L3 laboratory reared to adult; same locality / 06. VII. 2019 / Y. J. Tsao leg., 2 L3, 6 L3 laboratory reared to adult. Tongxiao, Tongxiao Township / 21. XII. 2019 / Y. J. Tsao leg., 1 L3 laboratory reared to adult. New Taipei City. Bali District 3rd Cemetery, Bali District / 30. X. 2018 / C. Y. Chiang leg., 4 L3 laboratory reared to adult; same locality / 06. XI. 2018 / C. Y. Chiang leg., 1 L3 laboratory reared to adult; same locality / 29. VIII. 2019 / Y. H. Lin leg., 1 L3, 4 L3 laboratory reared to adult; same locality / 04. IX. 2019 / Y. H. Lin leg., 4 L3 laboratory reared to adult; same locality / 24. II. 2020 / Y. H. Lin leg., 2 L3, 4 L3 laboratory reared to adult. Taichung City. Dakeng Trail No. 4, Beitun District / 24. VI. 2020 / Y. H. Lin leg., 1 L3 laboratory reared to adult.

Bio-ecology: M. bimaculatus is an inland species, and it is usually found at low elevations at about 100 m a.s.l.. The larvae build pitfalls in protected areas, such as under rock overhangs or under artificial buildings, and it was even found in a wood factory, where the larvae build pitfalls in sawdust. The behavior of curling up their bodies when disturbed, like B. asakurae and M. alticolus , was also observed in this species. The larvae may co-habitat with those of M. littoralis .

Distribution: Previously recorded in the southeast provinces of China. This is the first record of M. bimaculatus in Taiwan, also in the surrounding islands— Kinmen.

Remarks: The larvae of M. bimaculatus have their ventral head markings similar to M. punctinervis , though broader and longer. The larvae are also distinct from the Myrmeleon species of Taiwan in the shorter setae underneath labial palpus and the behavior of curling up when disturbed.

Variations exist on ventral head markings of M. bimaculatus , as the stripes may be broken into 2 spots, these variations may cause misidentification with the larvae of M. punctinervis or M. heppneri .

Figures

Fig. 3. Head of 3rd instar larvae of Myrmeleontini of Taiwan, ventral view; A, Baliga asakurae; B, Myrmeleon alticolus; C, Myrmeleon bimaculatus; D, Myrmeleon heppneri; E, Myrmeleon littoralis; F, Myrmeleon persimilis; G, Myrmeleon punctinervis; H, Myrmeleon taiwanensis; I, Myrmeleon wangi. Scale bar = 1 mm.

Fig. 4. IX abdominal sternite of 3rd instar larvae of Myrmeleontini of Taiwan, ventral view; A, Baliga asakurae; B, Myrmeleon alticolus; C, Myrmeleon bimaculatus; D, Myrmeleon heppneri; E, Myrmeleon littoralis; F, Myrmeleon persimilis; G, Myrmeleon punctinervis; H, Myrmeleon taiwanensis; I, Myrmeleon wangi. Scale bar = 1 mm.

Fig. 7. Myrmeleon bimaculatus Yang, 1999, 3rd instar larva. A, dorsal view; B, ventral view; C, lateral view.