Sericinus montela, Gray, 1852, Gray, 1852
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publication ID |
https://doi.org/10.1080/00222933.2023.2167620 |
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DOI |
https://doi.org/10.5281/zenodo.17552428 |
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persistent identifier |
https://treatment.plazi.org/id/03D987B4-E809-160C-FF13-83E2B8BFB8FB |
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treatment provided by |
Plazi |
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scientific name |
Sericinus montela |
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General larval morphology
The final-instar larvae of Sericinus montela are of typical eruciform. The cylindrical trunk bears three pairs of thoracic legs, four pairs of abdominal prolegs and a pair of anal prolegs ( Figure 1 View Figure 1 ). The head is orthognathus, with the mouthparts directed ventrally. The larval trunk is furnished with a pair of prominent filaments (PF) and a Y-shaped eversible osmeterium (Os) on the prothorax, and three rows of verrucae (Vr) arranged on the dorsal, lateral and subventral surface, respectively ( Figure 1 View Figure 1 (b)).
Head
The head capsule is sclerotised, bearing a pair of antennae, six pairs of stemmata and a group of chewing mouthparts directed ventrally. The head capsule is black and hirsute ( Figure 1 View Figure 1 (b)). The number and position of cranial secondary setae vary greatly among specimens and may even be asymmetrical between sides on a single individual ( Figure 2 View Figure 2 (a,b)).The frontoclypeus is approximately triangular, bearing numerous secondary setae. The anteclypeus is subtrapezoidal and membranous, and bears six pairs of asymmetrical setae.
The larvae have six pairs of stemmata ( Figure 2 View Figure 2 (c)), which are generally equal in size. Stemmata 1–4 and 6 are protuberant and arranged in a semicircle. Stemma 5 is widely separated from the semicircle and located anteriorly near the antennal base.
Each antenna is located between stemma 5 and the mandible ( Figure 2 View Figure 2 (d)). The antenna is cylindrical and three-segmented, with the second segment being the longest ( Figure 3 View Figure 3 (a)). The second segment bears distally two sensilla chaetica (SC1 and SC2) and two sensilla basiconica (SB1 and SB2). The sensilla chaetica varied significantly in length, with SC1 being much longer than SC2. The third segment of the antenna is very short, bearing a sensillum basiconicum distally (SB3).
Larval mouthparts
The mouthparts are mandibulate, comprising a labrum, a pair of mandibles, a pair of maxillae and labia, and a tubular spinneret.
The labrum is trapezoidal profiling a V-shape notch, and equipped with 10 pairs of setae ( Figure 2 View Figure 2 (d)). The epipharynx has a pair of flattened sensilla digitiformia located on the lateral side, three pairs of sensilla chaetica at the anterior margin, and two pairs of sensilla campaniformia on the central area. In addition, the epipharynx is furnished with inconspicuous microtrichia on the proximal region ( Figure 3 View Figure 3 (b)).
The mandible is flattened and heavily sclerotised, forming 15 cusps (distal teeth) on the apical margin ( Figure 3 View Figure 3 (c,d)). The cusps are more prominent in the middle and gradually diminish to each side. The mandible bears two setae on the external surface ( Figures 2 View Figure 2 (d) and 3(d)).
The maxilla possesses two sensilla styloconica and three sensilla chaetica on the mesal lobe ( Figure 3 View Figure 3 (e)). The maxillary palp is two-segmented, and furnished with a sensillum digitiformium, two sensilla campaniformia (inset of Figure 3 View Figure 3 (e)), and 10 sensilla basiconica surrounding a styloconic sensilla basiconica at the apex ( Figure 3 View Figure 3 (e)).
The labium has a pair of labial palps and an elongated tubular spinneret ( Figure 3 View Figure 3 (f)). Each labial palp is furnished with a campaniform sensillum (SCf) basally, and a sensillum basiconicum (SB) and a sensillum styloconicum (SS) distally. The spinneret is tubular and protrudes ventrally.
Thoracic legs
The thoracic legs are five-segmented: each consists of a coxa, a femur, a tibia, a tarsus and a single claw on the apex ( Figure 4 View Figure 4 (a)). The coxa is furnished with plentiful microtrichia on the lateral and mesal surfaces. The femur, tibia and tarsus are sclerotised and bear dense setae on the mesal surface and sparse setae laterally. The claw is heavily sclerotised, with a sharp apex ( Figure 4 View Figure 4 (b)).
Abdominal and anal prolegs
The unsegmented proleg consists of a proximal base and a distal planta where the crochets arise ( Figure 4 View Figure 4 (c)). The proximal base bears abundant setae on the lateral and mesal surface. The planta is furnished with numerous microtrichia mesally ( Figure 4 View Figure 4 (c)). The crochets of the abdominal prolegs are triordinal mesopenellipse arranged in an incomplete circle ( Figure 4 View Figure 4 (d)). The crochets of the anal prolegs are remarkable for possessing combined mesal triordinal penellipse and lateral uniordinal series ( Figure 4 View Figure 4 (e)).
Osmeterium
The osmeterium is normally contracted into the prothorax ( Figure 1 View Figure 1 (a)), and stretches out as a yellowish Y-shaped gland if the larva is disturbed ( Figures 1 View Figure 1 (b) and 5(a)). When fully stretched, the osmeterium can be further subdivided into a glabrous basal stem and paired distal arms ( Figure 5 View Figure 5 (a)). The tubular arms of the osmeterium are hirsute distally ( Figure 5 View Figure 5 (b)), and furnished with numerous minor openings surrounded by clusters of microtrichia ( Figure 5 View Figure 5 (c)).
Epidermal derivates on the trunk
The paired protuberant filaments arise from the prothorax ( Figure 1 View Figure 1 (b)), and are externally wrinkled and black ( Figures 1 View Figure 1 (a) and 6(a)). The filaments are equipped with numerous spinous setae ( Figure 6 View Figure 6 (a)), which are internally hollow and furnished with acanthae on the surface ( Figure 6 View Figure 6 (b)).
The verrucae are arranged on the dorsal, lateral and subventral surfaces of the larval trunk ( Figure 1 View Figure 1 (b)). The verrucae are generally yellow, except for those on the dorsum of the metathorax ( Figure 1 View Figure 1 (b)), which are blackish terminally and yellowish proximally ( Figure 1 View Figure 1 (a)). The verrucae on dorsal and lateral surfaces are comparatively more prominent ( Figure 6 View Figure 6 (c)) than those on the subventral surface ( Figure 6 View Figure 6 (d)). All the verrucae are covered with luxuriant secondary setae ( Figure 6 View Figure 6 (c,d)), which are also furnished with numerous acanthae.
Spiracles
The respiratory system is of the peripneustic type; the larvae bear a pair of prothoracic spiracles and eight pairs of spiracles on the first eight abdominal segments ( Figure 1 View Figure 1 (b)). The spiracles are elliptical and generally similar in size ( Figure 6 View Figure 6 (e)). The spiracle is equipped with longer branched trichomes covering the whole orifice and shorter microtrichia arranged on the exterior ring ( Figure 6e View Figure 6 ).
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