Article

Spiders

From Munshipedia, the MBRAS digital historical encyclopedia

Spiders

Spiders

The study of spiders in the Malay Peninsula and Borneo, as documented in the Society’s journal literature, reveals a body of work that, while modest in volume, addresses questions of considerable taxonomic and anatomical significance. Two principal threads emerge from the archival record: the internal morphology of mygalomorph spiders, particularly the genus Liphistius, and the ethological study of the bird-dropping spider Ornithoscatoides in the Johor region. Together, these contributions illuminate both the structural relationships among spider families and the remarkable adaptive strategies employed by certain species in the region’s tropical habitats.

Taxonomic and Anatomical Significance

The most substantial contribution to the Society’s literature on spiders is B. H. Buxton’s 1924 note on the internal anatomy of Liphistius batuensis, a mygalomorph spider. Buxton’s work was motivated by a specific comparative question: whether Liphistius, long regarded as a primitive or transitional form within the order Araneae, possessed anatomical features that would clarify its phylogenetic position relative to the Theraphosidae (the tarantula family) and the Araneae Verae (the true spiders). His examination of two adult and two immature specimens yielded results that, in his assessment, resolved the question decisively in favour of a close alliance with the Theraphosids [1, p. 86].

The most detailed findings concern the coxal glands. Buxton reports that Liphistius possesses two coxal glands, located in segments III and V of the abdomen, each bearing labyrinth tubes that interlace and coil over one another to such an extent that it is impossible to distinguish the two systems in section [1, p. 86]. He notes that in the Araneae Verae the segment V gland has been lost entirely, a point of comparative importance. The coxal glands of Liphistius, he concludes, resemble those of Theraphosid spiders in every particular and are “not in any respect more primitive” [1, p. 86]. This finding carries direct taxonomic weight: if the glandular anatomy of Liphistius is indistinguishable from that of the Theraphosids, the genus cannot be regarded as a more basal or ancestral form relative to them.

Buxton also investigated the nervous system, specifically the five transient abdominal ganglia that had been observed in larval Theraphosids. He had hoped that these ganglia, if present in Liphistius, would be more permanent and thus provide evidence of a more primitive nervous plan [1, p. 86]. None of the four specimens examined showed any trace of such ganglia. The absence of these structures, combined with the coxal gland evidence, led Buxton to his overall conclusion that Liphistius is anatomically much more closely allied to the Theraphosids than the latter are to the Araneae Verae [1, p. 86]. This finding, though presented in a brief two-page note, represents a significant contribution to the understanding of mygalomorph phylogeny and challenges any interpretation of Liphistius as a living fossil occupying a position between the two major spider lineages.

Ethology and Distribution

The second thread in the Society’s spider literature concerns the bird-dropping spider, a genus whose name itself—Ornithoscatoides—encodes its most striking adaptive strategy. H. N. Ridley’s 1894 note reports the discovery of a specimen on Gunong Panti in Johor, which he considers probably distinct from O. decipiens, the species previously described by H. O. Forbes from Java and Sumatra [2, p. 173]. Ridley’s account, though brief, provides a clear description of the spider’s hunting behaviour, which had been previously documented by Forbes and the Rev. O. Pickard Cambridge in Wanderings of a Naturalist [2, p. 173].

The mechanism of deception is precise. The spider spins a thin web on a leaf to represent the watery portion of bird excreta, then lies on its back on the web, held in position by strong spines on the legs, to ambush butterflies that alight on the supposed dropping [2, p. 173]. Ridley’s own specimen had left its web—a thin circular white film on a wild plantain leaf—to feed on a captured red bug, a detail that confirms the predatory function of the mimicry [2, p. 173]. On comparison with Forbes’ description of O. decipiens, Ridley notes differences in body colouring and several structural points, leading him to conclude that the Johor specimen is likely a new species [2, p. 173].

The record thus establishes the presence of the genus in the Johor region of the Malay Peninsula, extending its known distribution beyond the Javanese and Sumatran localities previously reported. The identification of a probable new species on Gunong Panti also suggests that the genus may be more diverse in the region than earlier accounts indicated, though Ridley’s note does not proceed to formal description.

Research and Documentation

The Society’s literature on spiders, as preserved in the archival record, is characterised by brevity and specificity rather than comprehensive survey. Both contributions are short notes—two pages in the case of Buxton, two pages in the case of Ridley—yet each addresses a discrete and well-defined question. Buxton’s work is comparative-anatomical in method, employing dissection and histological observation to resolve a phylogenetic question of long standing in arachnology. Ridley’s note is field-observational, recording a new locality and a probable new species on the basis of morphological comparison with a previously described taxon.

The temporal span between the two contributions—Ridley’s note appearing in 1894 in the JSBRAS, Buxton’s in 1924 in the JMBRAS—reflects a shift in the Society’s entomological and arachnological priorities. The earlier period, represented by Ridley, was dominated by collection-based taxonomy and the documentation of new species from the region’s forests. The later period, represented by Buxton, reflects the maturation of comparative anatomy as a tool for resolving systematic questions that could not be answered by external morphology alone. Buxton’s explicit engagement with larval developmental stages and internal organ systems marks a methodological advance over the purely descriptive approach of the earlier work.

No broader survey of spider fauna in the Malay Peninsula or Borneo appears in the records examined. The two notes, taken together, represent the full extent of the Society’s published contribution to the subject as preserved in the archival evidence. They do not address ecological roles, economic significance, or the wider diversity of the order in the region. The record is limited to these two specific contributions, and no further generalisations about the study of spiders in the region can be drawn from it.

MBRAS Sources

References

  1. B.H. Buxton (1924). Notes on the internal anatomy of Liphistius batuensis, Abr JMBRAS 2(1): 85–86.
  2. H.N. Ridley (1894). The bird-dropping spider (Ornithos catoides) in Johor JSBRAS 25: 172–173.