L i t e r a t u r e      R e v i e w

The history on proper classification of Cerambycidae or Longicornia as a whole dated back to the middle and late nineteenth century by Leconte, A. White, J. Thomson, T. Lacordaire and F. P. Pascoe. Leconte was the first person to put forward the philosophical arrangement of longicorn beetles but his knowledge was restricted to the North American taxa (Pascoe, 1869; Fragoso, 1987). Thomson (1860) later treated all the longicorn genera of the then accepted families, namely Prionidae, Cerambycidae and Lamiidae in the "Essai d'une Classification de la Famille de Cerambycides". At present, these are accepted as the subfamily Prioninae, Cerambycinae and Lamiinae respectively.

The most comprehensive and fundamental taxonomic work on the Cerambycidae was first published in the eighth volume of Lacordaire's Genera des Coleopteres. In treating this group, the most important character used by Lacordaire was the appearance of faceted eyes, producing dichotomous keys comprising strongly or finely faceted eyes as priority (Pascoe, 1869). The consequence was the general division of the diurnally or nocturnally active cerambycid.

Owing to the difficulties of predetermining relative omatidia size, Fragoso et. al. (1987) proposed another approach based on genitalia structure. Their most convincing argument was the occurrence of different terminalia patterns among taxa traditionally grouped under the same tribe. The other argument was the differentiation of terminalia occured before the transformation of omatidia. Six distinctive terminalia patterns were characterised in their study and hence, two new categories were proposed, the supertribes Cerambycoinia and Trachyderoinia. Unfortunately, all taxa elucidated were of North American origin and lacked representative from Asia, Africa or Australian region. Despite this new concept, entomologists who work on this group of beetles in South-east Asia still adhere to the old but most practised concept (i.e. non-genitalia description) to maintain nomenclature stability.

The most well represented cerambycid collection from Borneo were the private collection of A. R. Wallace which later came into the possession of F. R. Pascoe. In his Longicornia Malayana, 72 holotypes of Cerambycinae collected from Sarawak were described as new (Pascoe, 1869). Although most of the descriptions were brief, they serve as a guideline and primary reference at present.

At the beginning of this century, taxonomic studies of the Cerambycidae in the Oriental regions were carried out by C. J. Gahan, C. Aurivillius and W. S. Fisher. Gahan (1906a, 1906b) gave a comprehensive coverage of most genera represented in the Indian Region and part of the Malaysian Subregion. On the other hand, Aurivillius (1910, 1912) and Fisher (1934; 1935) focused more specificly on the Cerambycidae from Java, Sarawak and Sabah.

In the past 50 years, work on cerambycids in this region owed much to the contributions by the late Judson Linsley Gressitt. His numerous papers (Gressitt, 1935a, 1935b, 1936, 1938, 1940, 1951a, 1951b, 1959) and monographs (Gressitt, 1951c, 1956; Gressitt & Rondon, 1970) which dealt chiefly with Prioninae and Cerambycinae, thoroughly documented the diversity of Oriental and Australian (Papuan Subregion) cerambycids, many of which are of direct concern to this study. For example, 29 species of Laos cerambycine are also recorded in Borneo.

In recent years, Masao Hayashi and Karl-Ernst Hudepohl are the only two entomologists actively doing taxonomic work on cerambycids in Borneo or nearby regions. Hayashi (1977, 1978, 1979, 1982, 1985, 1987) concentrated much of his work in Peninsular Malaysia and Sabah but also described several new species from Sarawak (Hayashi, 1969, 1975, 1976a). Concurrently, Hudepohl attended generally to the cerambycid fauna of the Philippines but also described several species from Peninsular Malaysia and Sabah (Hudepohl, 1987, 1983, 1988, 1989a, 1989b, 1990b, 1992b). At present, 189 species from 74 genera are known to occur in Sarawak as listed in Table 1.

Table 1. Present classification of the subfamily Cerambycinae of Sarawak.

                                                                                                                              Comparing to nearby regions, Gressitt (1951c) listed 572 species of Cerambycinae from China, 399 species from Laos which include 190 new species (Gressitt & Rondon, 1970), 61 species from Hainan Island (Gressitt, 1940), 186 species from Papua New Guinea including 57 new species (Gressitt, 1951a; 1951b; 1959) and 39 species from Micronesia (Gressitt, 1956). Hudepohl (1990a; 1992b) listed 61 species from the Philippines. Gahan (1906b) listed 310 species from India, Sri Lanka and Myanmar. Related to this are specimens collected from Sabah and Peninsular Malaysia. Relative geographical position and proximity of these areas are reasonable justification for the likeliness that these species might be found in Sarawak as well. This is summarised as shown in Table 2.

Table 2. Diversity of the subfamily Cerambycinae of Sarawak and comparison with the surrounding regions.

There is a big difference in species composition between Peninsular Malaysia and Sarawak where only 35 % or 51 out of 147 species recorded in the former are also found in Sarawak. Contrary, 52 % of the total species recorded in Sabah can also be found in Sarawak. This common similarity could be justified by the close proximity of these two areas and the fact that both are not isolated by any major natural barriers such as the South China Sea in the former case. The only possible geographical barriers is the mountainous areas at Malingan Range and Apo Duat Range, north-eastern tip of Sarawak adjacent to Sabah. The highest peak in the state, Gunung Murud, standing at 7946 m above sea level is situated in these ranges. Unfortunately, no data are available from Kalimantan, the Indonesian counterpart in the central and southern part of Borneo.

The Cerambycinae of Singapore has higher similarity to Sarawak than to Peninsular Malaysia. 58 % or 25 out of 43 species in Singapore are found in Sarawak as compared to only 16 species in Peninsular Malaysia. It is more logical to anticipate more similarity between Singapore and Peninsular Malaysia than otherwise since it is separated by a narrow Tebrau Strait to the peninsula. Any colonisation or immigration from the peninsula is no doubt easily than from Borneo.

The number of communal species of one particular region with Sarawak is correlated to its distant from Sarawak. The further a region is from Sarawak, the less number of communal species is recorded as indicated in Table 2. This figure dropped to 28 or 7 % of all known species in Laos and 15 species or 5 % in the Indian and Myanmar regions. To the north, it dropped to 4 species (6 %) in Hainan Island and 10 species (2 %) in China. For the Philippines in the north­eastern of Sarawak, this number stands at 18 species (30 %) while 5 species (5 %) in Micronesia, a group of South Pacific Islands further eastward from the Philippines. Similarity of the cerambycine fauna of Sunda Islands is represented by 26 species or 21 %. Papuan New Guinea which is nearer to Australian Regions exhibits only 8 communal species with Sarawak or 4 % of the island's total species.

All localities within the Malaysian and Philippines Subregions listed in Table 2 share some common genera with Sarawak. This figure ranges between 48 % to 84 % of each places which is equivalent to roughly 19 - 57 genera. Forty three out of a total of 115 genera present in China can be found in Sarawak as well. The interesting fact is that Papuan New Guinea in the New Guinea Subregions only shows 17 common genera with Sarawak from a total of 60 genera recorded in that region. Papuan New Guinea also exhibits many tribe that are not of Oriental origin. For example, the tribe Phlyctaenodini, Tessarommatini, Aphneopini, Piesarthrini, Uracanthini, Calliprasonini, Distichocerini and Tragocerini (Gressitt, 1959).