GUINEA: ANOPHELES (MYZOMYIA) CRISTATUS?

Transcription

1 A NEW ANOPHELINE LARVA IN NETHERLANDS NEW GUINEA: ANOPHELES (MYZOMYIA) CRISTATUS? by J. C. VAN HELL From the Malaria Laboratory of the Public Health Service of Netherlands New Guinea, Ho!landia) bttroduction (Received for publication May 12th, 1953) A batch of anopheline larvae were caught in January, 1952, near the beach of Base G in the vicinity of Hollandia harbour. Included in the batch were two larvae which differed so greatly from those known in Netherlands New Guinea, that I believed them to belong to a species I had seen in Indonesia, viz., A. (M) leucosphyrus yak. hackeri; this type had never been found in Netherlands New Guinea. What brought this species to mind was a report of the government doctor, v^ q St,oo'rE, that in December, 1951, during an investigation in the settlement region of Ransiki (near Manokwari) he had found some larvae which he identified as A. (M) leucosphyrus vat. hackcri. Unfortunately these larvae were not preserved and I was unable to examine them. At my request both Ransiki and Base G were thoroughly searched for this species of larvae, particularly in the hope of recovering the adult stage of the mosquito, either directly or by isolated breeding of the larvae. However, we failed to secure either; this was a pity as examination of the imago would have thrown light on the presence of one or more types of the Leucosph)v'us species, of which there are at present six or seven known in different countries of South-East Asia (from India in the West to Indonesia and the Philippines in the East). The eastern boundary of the region i.n which the various types of the Leucosphyrus species occur are the islands of Buton, Celebes, Sangihe and Talaud in Indonesia and Mindanao in the Philippines. Immediately east of Celebes the region of the Australasian anopheline fauna begins; however, in the Moluccas (the western part of the Australasian region) several anophelines of the South-East Asiatic fauna have penetrated and some of these have come as far west as Netherlands New Guinea. Still, L} E & Woorm I t, are of the opinion--and I think rightly so--that Sw[[[} aa} [i & Rom w^t,rrr (1932) are mistaken when they say they found A. aitkenii, A. barbirostris, A. karwari, A. philipp# ensis and A. tesselatus in New Guinea. After a two-year stay in Netherlands New Guinea (July 1950 to July 1952) during which time I made a thorough investigation of all species of anophelines, the only representative of the South-East Asian fauna I could identify was A. karwari, in the vicinity of Hollandia. This mosquito was caught for the first time by DE ROOK, in 1931, near Ilar, then a small settlement near the north shore of Lake Sentani, about 30 km. from the present Hollandia. Ki a & Hooas'r ^^I (1945) found A. karwari near Hollandia and later on it was caught in several localities in the neighbourhood (DE Roost, 1950; v^ H I, ). The four other species mentioned by Sw} I I E aa EI & Rot)E w^i m: were never again seen in Netherlands New Guinea, so that these early findings are probably due to mistaking them for species of the Australasian fauna. A. aitkenii and its varieties, as well as A. tesselatus (like several other South-East Asiatic species) have indeed been found in the Moluccas and in some

2 256 J.c. VAN HELL islands near New Guinea, but neither A. barbirostris, nor A. philippinensis were ever observed in the Moluccas or near New Guinea. In Indonesia, A. barbirostris occurs only in the Greater and Lesser Sundas: A. barbumbrosus occurs also in the Moluccas. The latter species has not yet been' found in New Guinea. As far as is known, A. barbirostris subspec. innore. VœSHO S occurs only in Celebes. A. philippinensis was reported from Merauke in the larval stage, but it turned out to be A. meraukensis. In July, 1952,.4. (M) cristatus? a. Larval head; b. clypeal hairs' c. shoulder hairs; d. thoracic palmate hair; e. palm hair tn first abdominal segment; f. leaflets from abdominal palmate (4); g. pecten; h. lateral hair of segment 4.

3 A NEW ANOPHELINE LARVA IN NETHERLANDS NEW GUINEA 257 Rook found A. subpictus near Biak on the Schouten Islands (a group of islands on the North coast of Netherlands New Guinea), which proved that this species had nearly reached Netherlands New Guinea. A. subpictus had already been found in the Australian part of New Guinea (Hints, 1925; LEE & WOODrotate, 1944). The foregoing demonstrates the possibility that more and more Asiatic anophelines may enter New Guinea during their easterly migration. It is therefore not impossible that the larvae we found belong to a South-East Asiatic species arriving from the West. Of course I also investigated whether the larvae belonged to a species of the Australasian fauna which had not hitherto been found in Netherlands New Guinea. Description of the larva, according to two, probably mature larvae. The colour was light brownish-yellow, on the whole well transparent. No visible spots. The length cannot be stated accurately as the live larvae were not measured, but it was similar to that of the maturepunctulatus larvae, with which they were caught. Estimated length about 5 mm. Head: Antennae with a small, unbranched hair laterally, at about one-third of the length of the antenna. There were very fine spines on the inner margins similar to those in other species. Inner anterior clypeal hairs: set wide apart, somewhat shorter than the antennae, carrying small side branches chiefly on the basal portion. Outer anterior clypeal hairs: a little longer than half of the inner anterior clypeal hairs, and with distinct side-branches. Postclypeal hairs: remarkably long, as long as the outer anterior clypeal hairs, with some distinct side-branches. The tops of these hairs reach much beyond the insertion of the inner anterior clypeal hairs. The insertion lies between that of the inner and outer anterior clypeal hairs. The frontal hairs were normal as regards length and branching. The inner sutural hairs were simple or forked; the outer sutural hairs were usually forked. Thorax: the inner shoulder hair had a strong shaft; it had 18 to 20 branches and a firm, pigmented tubercle. The middle shoulder hair was longer than the inner one and had a slender shaft with 9 to 11 branches. There was a large, pigmented tubercle at the base, which was not fused with that of the inner shoulder hair. The outer shoulder hair was simple, without a tubercle. Pleural hairs: all four hairs of the prothorax were simple, the three long ones as well as the shorter one. The long hairs of meso- and metathorax had no branches, like the shorter hair on the mesothorax. The short hair on the metathorax had two or three small branches. Palmate hairs: On the metathorax there was an imperfect palmate hair with 6-7 narrow, lightly pigmented leaves ending in a sharp point or thin filament. On the 1st abdominal segmenthere was an imperfect palmate hair with 5-6 narrow leaves which were less developed than those of the thoracic palmate hair, though they still contained pigment. On the 2rid abdominal segment there was a palmate hair with about 18 leaves, even more narrow than those of the palmate hairs on the following segments, ending in distinct filaments. On the 3rd to 7th segments there were fully developed pahnate hairs with leaves. /he shape of the leaves was slender and long, serrated at about three-quarters from the base, and tapering to a thin point. Lateral hairs (No. 6) on the abdominal segments 4 to 7, with 2 or 3 branches, which branched off on the basal half of the hair, at about one third, as reckoned from the insertion.

4 258 J.c. VAN HELL Pecten: on the 8th segment, with ten teeth, all of about the same length except for the first which was distinctly longer. The teeth had side-teeth on the basal half. The distance of the inner anterior clypeal hairs and the lateral, simple, small antenna hair would indicate the Myzomyia subgenus, whereas the unbranched pleural hairs point to the Neomyzomyia group, of which there are many representatives in New Guinea. Another characteristic of the latter group are the strong inner shoulder hairs with a large number of branches which are found in nearly all species. However, the most striking feature of this new larva was the very long, branched postclypeal hairs reaching beyond the front of the larva. There are only a few larvae in Netherlands New Guinea and in the Australasian fauna which have similar postclypeal hairs, viz., (1) A. (M) amictus amictus EDW^RDS, 1921, (2) A. (M) amictus hilli WOODHILL & LEE, 1944, (3) A. annulata, De ROOK 1930, (4) A. incognitus, BRUG (a) The new larva differs from A. (M) amictus amictus EVW^RDS 1921 in that (1) the postclypeal hairs are even longer and branched; (2) the outer sutural hairs of the new larva are forked, and those ofa. amictus have 2 to 6 branches; (3) the inner shoulder hair of A. amictus ha no tubercle, only a narrow shaft from which spring 6 to 7 branches, close to the base of the hair, whereas the new larva has a distinct tubercle and a firm, broad shaft with 18 to 20 branches; (4) the long pleural hairs of the new larva on the pro-, meso- and metathorax are all simple and unforked, whereas in A. amictus one of the long hairs in pro-, meso- and metathorax is strongly branched. (5) The new larva has a partially developed thoracic palmate hair with 6 to 7 narrow leaves. A. amictus only has a small hair with 3 branches. (b) The new larva differs from A. (M) amictus hilli by the same characteristics as from A. (M) amictus amictus, except that the postclypeal hairs of amictus hilli somewhat resemble those of the new larva because of their tendency to forking at the top; the outer sutural hair of amictus hilli is identical with that of the new larva. (c) The new larva differs from A. annulata r)e ROOK 1930 in that (1) the postclypeal hairs of A. annulata have more branches (7 to 9) than those of the new larva; (2) the inner sutural hairs of A. annulata have 4 to 5 branches, those of the new larva are simple or forked; (3) the pleural hairs of A. annulata are similar to those of A. (M)amictus amictus and are therefore quite different from those of the new larva. The shoulder hairs and thoracic palmate hairs show no distinct differences, though the number of leaves of the thoracic palmate hair in A. annulata is higher (12) than in the new larva (6 to 7). (d) The new larva differs from A. incognitus BP.u which WooDmtsO. 8: LEE consider to be identical with A. (M) amictus hilli--by the same characteristics as.it differed from A. (M) amictus hilli, but particularly by striking differences in shoulder hairs, pleural hairs, and by the absence of a thoracic palmate hair and a palmate hair on the first abdominal segment in A. incognitus. According to BRUG'S description, the frontal hairs of A. incognitus are different and are of different length from those of the new larva; in incognitus the inner frontal hairs are longest and the central ones shortest. The anophelines of the Australasian fauna which were found in 1944 to 1946, I I I!

5 A NEW ANOPHELINE LARVA IN NETHERLANDS NE,V GUINEA 259 riz., A. (M) hmgae BELKIN & SCHLOSSER 1944, A. (M) nataliae BELKIN 1945,,4. (M) koliensis OWEN 1945, A. (M) solomonis BELKIN, KNIGHT & ROZEBOOM 1945, and A. (M) clowi ROZEUOOr! & KNIGUT 1946 bear no resemblance to the new larva, as the postclypeal hairs of these species are much shorter and do not reach beyond the head. There are also other points of difference. After ascertaining all this we searched among other representatives of the Neomyzomyia group of the South-East Asiatic fauna, particularly the different types of A. (M) leucosphyrus. Among these, the larva of A. (M) cristatus KING & BAISAS 1936 resembled the new larva so closely as to be almost identical with it. A. cristatus has also the remarkably long, branched postclypeal hairs, the strong, markedly branched shoulder hairs on heavy not fused tubercles, the unbranched pleural hairs, an incomplete palmate hair on the thorax and on the first abdominal segment, the pecten on the 8th segment with 10 to 11 teeth, all of about the same length, as well as a well developed palmate hair on the 2nd abdominal segment. The larva of A. (M) leucosphyrus hackeri, described by DUNNEWOLD and found in South Sumatra, has very long, but unbranched postclypeal hairs and a palmate hair on the first abdominal segment instead of an incomplete fan. Also the short propleural hair is usually forked in this larva. A. (M) leucosphyrus var. hackeri (SWELLENGREBEL & RODENWALDT) of East Borneo, Celebes, Sangir and the Talaud islands is most probably a type closely related to A. (M) leucosphyrus var. hackeri EDWARDS 1921 of Malacca, A. (M) leucosphyrus var. pujutensis CogLEss 1948 and var. hackeri described by KING & BAISAS (1936). The var. hackeri of Celebes also has long unbranched postclypeal hairs, as well as long outer anterior clypeal hairs, the inner anterior clypeal hairs usually being simple, though sometimes bearing small side-hairs. Our new larva of Netherlands New Guinea bore less resemblance to the types of A. (M) leucosphyrus var. hackeri which occur in Indonesia (South Sumatra, Celebes and East Borneo) than to A. (M) cristatus KING & BAISAS from Mindanao (Philippines); therefore I propose to call it A. (M) cristatus until the breeding of isolated larvae--and the preservation of the larval skins--has shown what kind of adult mosquito emerges from this larva. The importance of A. (M) leucosphyrus as a malaria vector has been recognized for a long time in Borneo and Sumatra (ROPER, 1914; B^IS, 1920; DOORENBOS, 1925; STOKER, 1934 etc.). A. (M) leucosphyrus var. hackeri was found infected (N.I.I. 5 per cent) in Celebes (Malili) by BOUMAN (1941). Moreover our knowledge of A. (M) leucosphyrus as a malaria vector was greatly extended by CHARS: & CH^UrmUR¾ in Assam (1941), MCART}-IUR in British North Borneo (1947), and by the experiences of the armies in Burma (COYELL, 1944; AERIDI & ARTHUR, 1945). Investigations have shown that systematic examination of the different types of this species are necessary, and that as regards Netherlands New Guinea we shall be wise to continue our researches for the presence of this species. Summary Description of a hitherto unknown anopheline larva found in Hollandia (Netherlands New Guinea). The larva was characterized by (1) its very large, strongly branched postclypeal hairs reaching well beyond the front of the clypeus, (2) the inner anterior clypeal hairs widely separated at the base and with distinct side-branches on the basal half, (3) the large strongly branched shoulder hairs (inner and median), the basal tubercles of these hairs not being fused, (4) the pleural hair groups of the pro-, meso- and metathorax all with the

6 260 J.c. VAN HELL long simple hairs, (5) the thoracic palmate hair with 6-7 leaflets, (6) the palmate hair of the first abdominal segment with 5-6 leaflets undeveloped or slightly broadened, (7) the palmate hair of the second abdominal segment with 18 leaflets well developed and with differentiated filaments, and (8) the teeth of the pecten on the 8th segment mostly subequal in length. In every respect the larva resembles A. (M)cristatus KING & BAISAS, Mindanao, Philippines. The author proposes that the new larva be called A. (M) cristatus KiNG & B^ISAS, at least until the imago is known. Doorn (Netherlands) 11, Prins Hendrik weg REFERENCES BELKIN, J. N. (1945), J. Parasitol., 31,315.- BELKIN, J. N., KNIGHT, K. L. & ROZEBOOM, L. E. (1945), J. Parasitol., 31, CHRISTOPHERS, S. R. (1933), The Fauna of British India. Diptera 4 (Culicidae, Anophelini). London.- COLLESS, D. H. (1948), Proc. Linnean Soc. New South Wales, 73, parts DUNNEWOLD, R. (1934), Geneesk. Ttidschr. v. Ned.-Indi& 74, GATER, B. A. R. (1934), Aids to the Identification of Anopheline Larvae in Malaya. Singapore.- GATER, B. A. R. (1935), Aids to the Identification of Anoœheline Imagines in Malaya. Singapore. -- KING, W. V., in M. F. BOYD (1949), Malariology, Philadelphia, S^U'Nr ERS, Vol. 1, p. 506-KING, W. V. & HOOGSTRAAL, H. (1946), J. Nat. Malaria Soc., 5, KING, W. V. & BAISAS, F. E. (1936), Proc. Entom. Soc. Washington, 38, No. 5.- LEE, D. J. & WOODHILt., A. R. (1944), The anoœheline Mosquitoes of the Australasian region. Monograph No. 2, Dept. of Zoology, Public. Univ. of Sydney. - OXVEN, W. B. (1945), J. Parasitol., 31, REID, J. A. (1949), Proc. R. Entom. Soc. London, series B. Taxonomy, 18, pts. 3-4 (April).- Ross, E. S. & RADCLYFFE ROBERTS, H. (1943), Mosquito Atlas, Part 2: Eighteen Old World Anophelines important to Malaria. Philadelphia, American Entomological Society.-ROZE- BOOM, L. E. & KNIGHT, K. L. (1946), J. Parasitol., 32, 95.- STOKER, W. J. (1934), Geneesk. Tt7dschr. v. Ned.-Indig, 74, SWELLENGREBEL, N.H. & RODENWALDT, E. (1932), Die Anophelen yon Niederliindisch Ost-Indien. Jena, FISCHER.