WISE, K. J., 1952: A recent occurrence of the Cinnabar moth. (Tyria jacobaeae L.). The N.Z. Entomologist 1 (2) : 10. THE LARVA OF ANACAENA TEPIDA ( ...
REFERENCES CAMERON, E., 1935: A study of the natural control of ragwort (Senecio jacobaea L.) Journal of Ecology 23 ( 2 ) : 265322. MILLER, D., 1970: Biological control of weeds in New Zealand. Department of Scientific and Industrial Research Information Series No. 74. WISE, K. J., 1952: A recent occurrence of the Cinnabar moth (Tyria jacobaeae L . ) . The N.Z. Entomologist 1 ( 2 ) : 10.
THE LARVA OF ANACAENA TEPIDA (COLEOPTERA : HYDROPHILIDAE) FROM A ROTORUA HOT SPRING M. J. WINTERBOURN Department of Zoology, University of Canterbury, Christchurch.
SUMMARY The larva of Anacaena tepida Winterbourn is described and figured and criteria f o r distinguishing it from Laccobius mineralis Winterbourn a r e given. Updated information on the distribution of the 'thermal' Hydrophilidae a r e provided. INTRODUCTION F o u r species of Hydrophilidae (Coleoptera) a r e known to inhabit thermal waters in New Zealand (Winterbourn, 1970). The larvae of two of these, Enochrus tritus Broun and Laccobius mineralis Winterbourn, have been described and the larva of a third species Anacaena tepida Winterbourn is described below. I n J a n u a r y 1971, a single larval hydrophilid was found in association with adults of A . tepida in the effluent channel of a hot spring a t Ohinemutu on t h e shore of Lake Rotorua. The larva clearly belongs to the genus Anacaena Thomson a s outlined by Richmond (1920) and Balfour-Browne (1958) and a s A. tepida is t h e only representative of this cosmopolitan genus know f r o m New Zealand, the larval and adult stages can be associated with confidence.
Figs. 1-8: Anacaena tepida larva. 1, Labro-clypeus; 2, Left mandible; 3, Left maxilla; 4, Larva dorsal view; 5, Labium; 6, Left antenna; 7, Abdominal segment 2, dorsal; 8, Pronotal spines. Fig. 9 : Laccobius mineralis, labro-clypeus and left lateral expansion of epistoma of larva. Scale lines, Fig. 4 = 1 mm; Figs. 3, 6 = 0.05 mm; Fig. 7 = 0.2 mm.
DESCRIPTION OF LARVA Head elevated, golden-brown. Ocular areas in groups of 6 , indistinct, round-oval. Antennae (Fig. 6) 3-segmented; antenna1 appendage a s long a s apical segment. Frons rounded behind. Labroclypeus (Fig. 1) with a quadridentate median lobe bearing 4 short, stout setae. Lateral expansions of epistoma n o t identical, not pronounced and bearing f e w stout setae. Mandibles (Fig. 2 ) sharply pointed, symmetrical, with 3 inner teeth. Maxillae (Fig. 3 ) palpiform, basal segment with prominent stout setae on the inner margin. Ligula of labium (Fig. 5) 1-segmented, almost a s long a s the palpi. Pronotum 2.15 times a s broad a s long, sclerotized, golden, covered in minute multiple-spines (Fig. 8 ) , and occasional long setae. I t s anterior margin beasing a fringe of about 40 forwardprojecting setae. Mesonotum with 2 large and 2 smaller, more anterior sclerotized plates of irregular outline bearing sparsely distributed spines. Metanotum also with 4 sclerites, the posterior pair smaller and more coarsely spinose. Legs just visible from above; tarsus a little shorter than tibia. Abdomen somewhat truncate posteriorly with 8 visible segments plus stigmatic atrium. Pleural lobes prominent. Tergum of abdominal segment 1 with 1 pair of sclerites and 4 circular-oval patches of coarse spines. Segments 2-6 with narrow anterior and median plates and 1 0 small patches of spines (Fig. 7). Segment 8 with a rectangular-ovoid tergite. Cerci heavily sclerotized apically, each bearing a long, terminal seta. Length of larva 4 mm. Habitat: The larva was found in water beneath averhanging grasses n e a r the edge of a hot spring outflow channel. Water temperature a t the collection site was 3 8 ° C and the pH was 9.2. Adult beetles were common here as were adults and larvae of E. tritus and larvae of the ephydrid fly Ephydrella thermarum Dumbleton. COMPARISON W I T H LACCOBIUS MINERALIS Of the Hydrophilidae inhabiting thermal waters the larva of A. tepida most closely resembles t h a t of L. mineralis, b u t i t can be distinguished from the latter using a number of structural criteria. The abdomen of A. tepida i s broader and more truncate posteriorly and the plates and spines on the dorsal surface a r e arranged differently. The legs of A. tepida a r e shorter, and L. mineralis lacks the row of conspicuous stout setae on the anterior margin of the pronotum which a r e present, in A. tepida. In both species the mesoand nietathoracic sclerites a r e reduced b u t in L. mineralis they a r e more widely separated. Several differences a r e shown by the mouth parts. The labium of L. mineralis lacks a ligula which is present in A. tepida, the mandibles of t h e f o r m e r a r e asymmetrical whereas those of the l a t t e r a r e symmetrical and t h e labro-clypei
and epistomial expansions a r e quite different in form (Figs. 1, 9 ) . More detailed examination of further material of L. mineralis since the original description was made has shown that most of the spines on the left lateral expansion of the epistoma possess short, accessory spines on their inner sides. This is a feature not noted by Richmond (1920) in his description of the larva of Lac cobius agilis Randall. DISTRIBUTION O F HYDROPHILIDAE I N THERMAL WATERS Further collecting in warm springs throughout New Zealand over the last two years has extended knowledge of the geographic distribution, temperature and pH ranges occupied by the Hydrophilidae. This information is summarized in Table 1. TABLE 1 Distribution of Hydrophilidae in warm springs in New Zealand. Species Temperature pH Locality range ( " C ) range Enochrus tritus
28-45
3.2-8.0
Anacaena t e ~ i d a
33-44
6.0-9.2
Laccobius mineralis
27-38
3.7-8.0
Paracymus sp.
34
3.2
Waipahihi Stm. (Taupo), Ohinemutu, L. Rotowhero, Waiotapu, Waimangu. Waiaahihi Stm.. ~hinemutu, Waiotapu, Wainiangu. Waiaahihi Stm.. ~aiotapu, Waipuwerawera Stm. (Taupe ) , Copland R. (S. Westland). L. Rotowhero.
The three main species are widely distributed in the RotoruaTaupo region although none have been found in the Tokaanu thermal area despite searching on three occasions. They occur over wide temperature and pH ranges and in similar habitats, notably along the margins of warm lakes, ~ t r e a m s and spring effluent channels. The most interesting distributional record obtained is that lo^ L. mineralis in the hot springs a t Welcome Flat on the Copland Rives, South Westland. This considerably extends the range of this species which has not been found, however, in other South Island warm springs a t Hanmer, Maruia, Fox Glacier and Franz Joseph. REFERENCES BALFOUR-BROWNE, W. A. F., 1958: British Water Beetles, 3. Ray Society, London. RICHMOND, A., 1920: Studies on the biology of the aquatic Hydrophilidae. Bull. Amer. Mus. Nat. Hist. 42: 1-94. WINTERBOURN, M. J., 1970: The Hydrophilidae (Coleoptera) of New Zealand's thermal waters. Trans. R. Soc. N.Z., Biol. Sci., 12 (4) : 21-28. 174
