Key to Larvae of Species Treated in this Paper
|Antennae 2-jointed; eusternum not defined anteriorly from presternum; pigmented spinules absent||Paroplites australis Er.|
|Antennae 3-jointed; eusternum distinct from presternum anteriorly; pigmented spinules present on body segments||Prionoplus reticularis White.|
Genus Paroplites Lameere
Paroplites australis (Erichson) (Figs. 1–3).
Mature Larva. Form robust, cylindrical, tapering slightly posteriorly. Colour -white. Length, 55–70 mm.
Head (Fig. 1) widest posteriorly. Posterior margin of epicranium not as deeply emarginate as in Prionoplus. Anterior foramen subtriangular. Dorsal plate of mandible (Figs. 2 and 3) with a longitudinal groove. Labrum transverse, suborbicular. Clypeus membranous, unpigmented. Epistoma produced on each side into a wide, blunt process. Front produced over epistoma in a non-dentate carina which is not continuous across the median line. Setae absent behind frontal carina. Post-condylar carina curved, no setae arising from it. Two setae anterior to the carina. Front behind carina with sparse short setae. Median impressed line distinct, frontal sutures not distinct. Antennae 2-jointed, with basal membrane. Joints subequal in length, 1st cylindrical, slightly longer than wide, 2nd tapering to apex which is obliquely truncate and bears on the top the supplementary joint. Ocelli three, indistinctly visible. Subfossal process obtuse. Genae with sparse setae. Maxillary sclerite with a number of short setae. Maxillary palpi 3-jointed, 1st transverse, 2nd subglobose, 3rd elongate slightly longer than last joint of labial palp. Mala with dense stout setae. Mentum produced at anterior angles which bear setae and with a single seta on each side posteriorly. Submentum with a single seta on each side at mid-length. Ligula with dense stout setae. Labial stipes pigmented posteriorly on each side and bearing a few setae anteriorly on each side. Gula not distinct. Hypostoma without setae.
Thorax. Eusternum not distinct from presternum anteriorly. Legs well developed, 4-jointed, 2nd and 3rd joints sclerotized and pigmented. Setae stronger and denser than in Prionoplus. No spinules anteriorly on epipleurum.
Abdominal segments with sparse moderately fine setae but without pigmented spinules. Ampullae unarmed. Pleural discs on segments 1–6 indistinct. Spiracles large, oval, with pecten occupying part of posterior margin of mesothoracic and abdominal spiracles. No sclerotized thickening of hind intestine.
Specimens of larvae and adults of this Australian beetle were sent by the Public Works Department, from imported power poles in the Manawatu and Waikato districts. It is likely that these poles were infested prior to their arrival in New Zealand as the larval period of the Prioninae may be as much as four years. The species is recorded from Banksia, elm, and willow in Australia, and it is probable that this beetle could easily become established in New Zealand.
Genus Prionoplus White
Prionoplus reticularis White (Figs. 4–7)
Egg. Fusiform, 3.0 mm long and 1.2 mm wide, colour white, chorion not sculptured.
First Stage Larva. Resembles the mature larva in form but differs in that the triangular processes of the epistoma, the frontal carina and the post condylar carina are absent.
Mature Larva. Form robust, cylindrical, slightly tapering posteriorly. Colour creamy-white. Length, 50–70 mm.
Head (Fig. 4) widest behind mid-length, posterior margin of epicranium deeply emarginate. Anterior foramen subtriangular. Mandible (Figs. 5 and 6) triangular, black and shining, basal half rugose and bearing a number of setae on the outer face, ventral apex produced acute, dorsal plate finely striate. Labrum subcordate, castaneous, slightly longer than wide, anterior margin densely setose and with several setae on each side of the disc. Clypeus membranous and unpigmented. Epistoma produced on each side into a small triangular lobe projecting over the posterior angle of the clypeus. Front produced over the epistoma in an obscurely dentate carina which is not continuous across the median line. Post-condylar carina with three or four setae arising from it near the inner end and with two setae anterior to the curve at the lateral extremity behind and between the antenna and the dorsal condyle of the mandible. Front behind carina with short sparse setae. Median impressed line and frontal sutures distinct. Antennae 3-jointed with a basal membrane, 1st joint transverse, 2nd joint subglobose bearing supplementary joint on apex, third joint minute subcylindrical less than half as long as 2nd and much narrower. Ocelli absent, no corneal lens but three pigmented spots may be indistinctly
Text-fig. 1.—Paroplites australis. Fig. 1—Larva, head. Fig. 2—Larva, mandible, external face. Fig. 3—Larva, mandible, buccal face. Prionoplus reticularis. Fig. 4—Larva, head. Fig. 5—mandible, buccal face. Fig. 6—Larva, mandible, external face. Fig. 7—Larva, prosternum.
visible beneath the gena. Sub-fossal process obtuse. Genae with sparse moderately stout setae and a number of shorter setae. A number of setae along anterior margin of epicranium behind frontal suture. Maxillary sclerite with a number of short setae. Maxillary palpi 3-jointed conical, 1st joint slightly transverse, 2nd slightly quadrate, 3rd subconical shorter than 2nd and subequal to last joint of labial palp. Mala with dense stout setae. Mentum bearing a number of setae. Submentum not sharply defined from mentum, somewhat pigmented anteriorly. Ligula twice as wide as long with moderately dense stout setae, pigmented posteriorly on each side. Labial stipes bearing about six setae on each side. Gula not distinct. Hypostoma without setae.
Thorax. The thoracic segments bear sparse short setae, the meso- and meta-thorax and the eusternum, sternellum, coxal lobes and hypopleura of the prothorax bear short pigmented spinules. The presternum (Fig. 7) of the prothorax bears no pigmented spinules except in the posterior angles and is distinctly separated from the eusternum. The epipleurum bears a few spinules in the posterior ventral angle. The legs are well developd and 5-jointd. The coxal lobe is bounded anteriorly by the eusternum and the epipleurum and posteriorly by the sternellum; trochanter annular, mesally with 2 long and one short setae; femur subglobose with about 12 setae on apical half; tibia subcylindrical with about 10 setae on distal half; tarsus subconical. Femur and tibia unpigmented. The mesothoracic spiracle is large and oval with the pecten consisting of about 40 teeth occupying the dorsal half of the posterior margin.
The abdominal segments, including the ampullae, bear sparse short setae and short pigmented spinules. The pleural discs are present on segments 1–6 but are most prominent on the first three segments. Spiracles large, oval, with the pecten occupying the whole posterior margin. Sclerotized and pigmented thickening of the intima of the hind intestine absent.
Pupa. Form as in adult. Length, 35–40 mm. Head with sparse short setae. Pronotum with short setae and a blunt tubercle at midlength on lateral margin. Mesonotum with sparse pigmented setigerous spinules and a posterior median tubercle. Metanotum with sparse pigmented setigerous spinules and a small rounded tubercle on each side close to the anterior margin. Triangular processes are present on the trochanters, small on the anterior, larger on the middle and largest on the hind trochanters.
Abdominal segments 1–8 dorsally beset with short pigmented setigerous spinules and short hairs, smaller and sparser on the 8th than on preceding segments. The dorsal tubercles are indistinct on the 1st segment, more strongly developed on 2nd and 3rd, prominent and bituberculate on segments 4–6, and poorly developed on the 7th. Posteriorly the abdomen ends in two conical horns which are slightly pigmented at the apices.
The larvae of this beetle infest the dead trunks and stumps of native podocarps and exotic conifers such as Pinus radiata. It is occasionally recorded as damaging structural timber, but this seems to occur only when the timber is in a damp situation. The female has been observed (by J. G. Myers) to lay as many as 570 eggs. These are deposited in large numbers in cracks and crevices. The larval period is not definitely known but is probably in excess of two years. This species is the only native representative of the subfamily Prioninae.