Lagideus podocarpus Smith, 2016

Boeve, Jean-Luc, Marin-Armijos, Diego S., Dominguez, Diego F. & Smith, David R., 2016, Sawflies (Hymenoptera: Argidae, Pergidae, Tenthredinidae) from southern Ecuador, with a new record for the country and some ecological data, Journal of Hymenoptera Research 51, pp. 55-89 : 59-63

Lagideus podocarpus Smith sp. n.

Figs 9 , 10 , 11

Description.

Female. Unknown.

Male. Length 7.0 mm. Antenna and head black; labrum and mouthparts white; mandible dark red brown. Thorax black with posterior corners of pronotum orange. Fore and midlegs light orange; fore coxa black with white stripe on outer surface and extreme apex white; mid coxa black with extreme apex white. Hind legs black with extreme apex of coxa, trochanters, and extreme base of femur white and about basal half of tibia light orange. Wings hyaline; veins and stigma black.

Head with vertex and frons shiny, very few widely scattered punctures; area adjacent to inner orbits slightly dull, micropunctured; with long golden hairs, as long as or longer than second antennomere. Antenna 1.5 × head width; antennomeres 4-8 bipectinate, antennomere 3 unipectinate with inner ramus absent to very slightly indicated ( Smith 2012: fig. 25); apical antennomere with rami less than half length of stem. Malar space linear. Thorax shiny; mesonotum with distinct punctures, separated by flat shiny interspaces more than puncture diameters; with long golden hair on dorsum and grey to white hair on pleurae and sterna. Hindbasitarsomere slightly longer than length of remaining tarsomeres combined; inner hind tibial spur about 0.6 × length of basitarsomere. Genitalia in Fig. 10 ; parapenis uniformly broad, not distinctly indented on posterior margin; valviceps of penis valve with dorsal margin concave.

Type material.

Holotype labelled "Ad.M, ex-larva," "ECUADOR: Cajanuma, Podocarpus NP, 04°07'S, 079°10'W, 2810 m, X.2014, on Fuchsia vulcanica , JLBoevé leg. RBINS, EtOH100%, P3898.etc>10" (RBINS). Paratypes: Same data as for holotype except P3898.etc>01 (1 ♂), P3898.etc>02 (1 ♂), P3898.etc>03 (1 ♂), P3898.etc>04 (1 ♂), P3898.etc>05 (1 ♂), P3898.etc>06 (1 ♂), P3898.etc>07 (1 ♂), P3898.etc>08 (1 ♂), P3898.etc>09 (1 ♂), P3898.etc>11 (1 ♂), P3898.etc>12 (1 ♂), P3898.etc>14 (1 ♂); these specimens are in RBINS, USNM and MUTPL.

Other material.

Cajanuma, Podocarpus NP, 04°07'S, 079°10'W, 2810m, 11.10.2014, on Fuchsia vulcanica ( Onagraceae ), P3898 (6 larvae), 14.10.2014, on F. vulcanica , P3917 (4 larvae), P3919 (20- 30 larvae), 23.10.2014, on F. vulcanica , P3968 (> 30 larvae), P3969 (6 larvae), P3970 (6 larvae), P3976 (4 larvae), leg. J.-L. Boevé.

Etymology.

Named for Podocarpus National Park, Ecuador, where the collections were made; a noun in apposition.

Comments.

Although only the male is known, it differs from described species, and we prefer to have a name since it was reared and the life history and host plant are known. Only females are known for most species of Lagideus , and this could be the opposite sex of one of those. However, this won’t be known until the sexes are associated.

The bipectinate antennomeres 4-8 and unipectinate antennomere 3 will take this species to couplet 17c in Smith (2012) which includes L. longicus Smith and L. tapanti Smith, both known from Costa Rica. The black antenna and similarity of genitalia will put it closest to L. longicus .

Lagideus tapanti has white hairs on the head and body, antennomeres 1-3 or 4 yellowish, thorax black, and legs black with the base of the femora white; the antenna ( Smith 2012: fig. 25) has the rami of the apical antennomere much longer than the stem; and the parapenis of the male genitalia are lobed posteriorly with a central, shallow posterior emargination ( Smith 2012: fig. 28). Lagideus longicus is entirely black and the apical antennomere has long rami as in L. tapanti ; the parapenis of the genitalia is distinctly indented posteriorly for at least a third of its medial length ( Smith 2012: fig. 29); and the valviceps of the penis valve have a straight dorsal margin ( Smith 2012: fig. 33).

Lagideus podocarpus can be distinguished from both these species by light orange posterior corners of the pronotum; the light orange fore and mid legs (except the partly black coxae); basal half of the hind tibia light orange; the antennae, similar to L. longicus ( Smith 2012: fig. 25) except the rami of the apical antennomere are short, less than half the length of the stem; and the male genitalia (Fig. 10 ) which has the parapenis nearly uniformly broad, without a central posterior emargination and the valviceps of the penis valve distinctly concave dorsally.

The length varies slightly 6.0-7.5 mm. The tegulae may be black to brown or partly light orange as are posterior corners of the pronotum.

Life history.

The population of L. podocarpus at Cajanuma (Fig. 11 ) consisted of larvae found within a circumference of ca. 100 m, on several patches of the host plant, F. vulcanica L. ( Onagraceae ). The larvae were attached to the underside of a leaf and they were generally aggregated in that one or a few individuals occurred per leaf. Younger larvae skeletonised the leaves and made holes in the leaf, whereas larvae of later instars attacked the leaf up to its edge. Larvae fed on both younger and older leaves. One large patch of flowering plants clearly harboured fewer larvae than the smaller and more numerous spots of non-flowering plants. The larvae being kept in rearing still appeared as healthy, despite the fact that the offered leaves (during November 2014) were less fresh and rather decaying. A couple of plant species and varieties were also offered to them to roughly establish their diet breadth. Fuchsia ‘Koralle’ was rather accepted, whereas only very few small holes were made on leaves of Fuchsia 'Gartenmeister Bonstedt’. These two varieties are cultivars of Fuchsia triphylla that is related to F. vulcanica (Marc Reynders, personal communication). A leaf of Oenothera sp. ( Onagraceae ) was also tested, but not accepted.

Larvae of nearly all instars were found in the field, but no adults were collected by sweeping. Among the larvae kept in rearing, several individuals reached the eonymph stage (Fig. 11g-h ), during the first ten days of October 2014. They formed a cocoon between fresh or rather decaying leaves (Fig. 11i ), or in an offered layer of moistened sand. At the end of October, prepupae and cocoons occurred in the rearing. A total of 14 adults, all males, emerged from 20.11 to 12.12.2014.

Once disturbed, a larva of L. podocarpus reacted immediately by raising its abdomen (Fig. 11j ), then slowly lowering it. This reaction could be repeated several times, under successive disturbances. After several such behaviours, the larva tended to slightly walk backwards. The prepupa reacted under disturbance by curling its body and making some slow movements. To further investigate the larval defensive behaviour, a dozen workers of the ant species Eciton burchellii Westwood ( Formicidae ) were collected in the field (Pueblo Viela, 15.10.2016), held without feeding, and used ca. 36 h later. The bioassay consisted of placing seven ant workers and one larva settled on a host plant leaf in an open box, the interactions being then filmed. As far as no ant contacted the larva, the latter remained merely immobile. But once contacted, the larva instantly raised its abdomen and directed the apical filaments towards the aggressor (Fig. 11k-l ). Thus, these filaments seem to play a major role in defence. Their size is impressive, with a length of 13 mm for a remaining body size of 16 mm. The filaments resemble those of the larvae of Philomastix ; the two genera are sister-groups ( Schmidt and Walter 2014). However, the filaments protrude from the apical segment in Lagideus and the ninth one in Philomastix ( Smith and Bado 2004). Moreover, it seems that they are clearly covered with spines in Lagideus only (Fig. 11 ; Smith and Bado 2004). It is unclear whether the defence is only physical, or includes chemical compounds. Larvae of Pergidae contain toxic peptides which are active against vertebrates and invertebrates ( Boevé et al. 2014), but whether Lagideus sp. contains such compounds remains unknown.

Note that another sawfly species ( Tenthredinidae ) was found among the collected leaves (and stems) of F. vulcanica , but in much lower numbers (2 individuals: 11.10.2014, P3899, and 14.10.2014, P3919.C1) than Lagideus sp. (>90 in total). This plant constitutes a host plant, since a larva of the tenthredinid was placed on an intact leaf and the larva ingested significant parts of it.

Figures

Figure 9. Lagideus podocarpus, male (P 3898. etc> 13), body length 6.0 mm. a Dorsal view b ventral view.

Figure 10. Male genitalia of Lagideus podocarpus. At left, genital capsule, ventral view; at right, penis valve, lateral view with dorsal margin to right.

Figure 11. Life history traits of Lagideus podocarpus. a A patch of the host plant Fuchsia vulcanica b a plant with feeding damage, seen from above c-e larvae attached to the underside of leaves, seen from below f a larva that just moulted with exuvia visible g, h prepupal stage i cocoon j screenshot of a video clip, the thorax of the larva was touched with flexible forceps a second before k, l two screenshots of a video clip performed during a bioassay, both being spaced by 1 sec: an ant is approaching the larva (first screenshot), then touching it, which immediately provokes the defensive behaviour of the larva that directs its caudal filaments towards its aggressor (second screenshot).