l~ccords of the Western Auslralwn Museum Supplement No. 52: 67-71 (1995).

Coxal glands of of the genera Bymainiella, and (, , )

Robert J. Raven Queensland Museum, P.G. Box 3300, South Brisbane, Queensland 4101, Australia

Abstract - Knowledge of coxal glands in mygalomorph and liphistiomorph spiders is reviewed. The hexathelid species Bymainiella terraereginae (Raven) has vesicles and coxal gland outlets associated with coxae I, 11, and III - the most plesiomorphic state in any known . Bymainiella lllgllbris Raven, Atrax (Hexathelidae) and Namea (Dipluridae) have coxal gland outlets on at least coxae I and Ill.

INTRODUCTION terraeregil1ae (Raven) were functional. In fact, those Coxal glands are the prosomal excretory organs book-lungs have as many leaves as the anterior of . Their structure is discernible only pair. Because the sections were of good quality, I through histological sectioning. By the early 20th sought to elucidate other structures of interest. century many studies on coxal glands of arachnids This paper recognises the contributions of Or had been made. However, those studies were to and its direc­ found inconsistent by Buxton (1913, 1917, 1924) tions in Western Australia. who reviewed them and systematically examined coxal glands of representatives of all living arach­ nid orders. In most arachnid groups, one saccule MATERIALS AND METHODS occurs in either coxae I (Solifugae, The results are based upon serial sections of Mygalomorphae, and Amblypygi) Bymail1iella terraeregil1ae (Raven, 1976), B. lugubris or in coxae III (Scorpionida and Opilionida) Raven, 1978, and unnamed species of Atrax and (Buxton 1913). The outlets of coxal glands Namea. All spiders were immature (not embryon­ are of two states: 1, most mygalomorph spiders ic), as were those of Buxton (1913). Specimens of and the plesiomorphic Liphistius have two both Bymail1iella species were pre-penultimate or outlets, one each on coxae I and Ill; 2, most older. Spiders were fixed either in Bouin's fixative, Araneomorphae and a diplurid mygalomorph 10% formalin, or a mixture of ethanol, 2% glacial have an outlet only on coxae 1. acetic acid, water, and glycerol. Specimens were Since Buxton's definitive three works (1913, 1917, impregnated in a methyl-benzoate celloidin solu­ 1924), the gross morphology of coxal glands of oth­ tion and embedded in wax. Sagittal sections were er spiders has almost been ignored. Todd (1942, cut at 8-15m. They were stained with Mann's unpublished MSc. thesis) examined the internal methyl blue-eosin for 1-2 hours; the "blue" was anatomy and described coxal glands of all five then fixed with water or a ni} solution of ammoni­ New Zealand mygalomorph genera. Petrunkevitch um hydroxide. Sections were counterstained by (1933) succeeded only in misreporting Buxton's immersion of ca. 20 seconds in 70'X} ethanol with 10 findings. Millot (1933) also examined coxal glands drops of Orange G per 100ml. The specimen of B. of Liphistius and confirmed Buxton's findings. terraeregil1ae was subadult with carapace length of Marples (1968) examined only hypochiloids. Gabe 3mm; the carapace of adult females were 3.68­ (1968) noted the cytology and histochemistry of 5.63mm long (Raven 1976). coxal glands of four araneid species including the nemesiid, caemel1taria. Platnick and Gertsch (1976) used the number of coxal gland outlets to THE STRUCTURE AND POSITION OF support their hypothesis of the relationships of spi­ COXAL GLANDS der suborders. Also, Lopez (1983) remarked upon Coxal glands consist essentially of three compo­ the extensiveness of what he regarded as modified nents: 1, the labyrinth; 2, the saccule; and 3, the exit coxal glands in Metepeira (Araneidae). tubule. The labyrinth is a highly convoluted tube The initial object of this study was to determine lying beside and above the endosternite (16, Fig. 1). whether the small posterior book-lungs of B. Anterior to and above each exit tubule the laby- 68 R.J. Raven

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..... ' .. ' , / .I maxilla i 6 .'

Coxa 1

24

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.... .I

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...... /' '. . ':~ .,\ " ...... \t.. •...... - 5 ..... ::-:~ . cq.xa 4 1

Figure 1 Bymainiella terraereginae, prosoma: 1-10, Digestive system. 1, anterior pharyngeal horn; 2, pharynx; 3, oesophagus; 4, sucking stomach; 5, midgut; 6, anterior branch of midgut diverticula; 7-10, lateral branches of midgut diverticula to coxae I-IV, respectively. 11-16, coxal glands: 11, 12, saccules; 13-15, vesicle and outlet (arrow) on coxae I-Ill; 16, coxal gland labyrinth. 17-23, endosternite and associated muscles: 17-20, suspensor I-IV respectively; 21, Suspensor centralis; 22, Protractor endosterni(?); 23, Dilator proventriculi lateralis. 24, dorsal ganglionic nerve mass. 25-29, Arterial system; 25-28, latertal aortae to coxae I-IV respectively (maxillary aorta omitted); 29, anterior aorta.

rinth enlarges into a vesicle (V, Fig. 4). From there Fig. 4) are presumably nephrocytes. it narrows and becomes the exit tubule (ET, Figs. 3, B. terraereginae has vesicles and associated gland 4) that opens into the posterior upper corner of outlets in coxae I and Ill, as do most either coxae I, 11 or Ill. Posterior to coxae 11, the mygalomorphs known. However, an additional coxal glands curve entally and thus it is not possi­ outlet and vesicle is associated with coxa 11 (Figs 2, ble to show the three outlets in one section. Large, 3, 4). The thin-walled saccules associated with cox­ thin-walled cells with darkly stained nuclei (Ne, ae I and 11 are evident; however, no saccule was Mygalomorph spider coxal glands 69 observed near coxa Ill. The labyrinth passes poste­ mygalomorphs.] Hence, both by outgroup compar­ rior to ental coxae IV (Fig. 1). Moreover, the ental ison and embryology, the most plesiomorphic con­ limb of the labyrinth lying dorsal to the dition in spiders is that reported here for B. endosternite is not highly convoluted and a much tcrraereginac. longer vesicle extends ectally into coxae n. Platnick and Gertsch (1976) hypothesized that the In sagittal sections of B. lllgllbris, coxal gland out­ were the most plesiomorphic spiders lets and vesicles associated with coxae I and III are and used the one outlet condition (as one of five evident. However, the poor quality of available characters) of araneomorphs to support their sections did not allow either the confirmation or . Clearly, the findings of Buxton and falsification of the presence of outlets and associat­ those presented here support neither araneomorph ed vesicles in coxae n. Also, in good quality sagit­ monophyly nor the plesiomorphic state of the tal sections of Atrax and Namea, coxal gland outlets . Although B. terraereginae has six spin­ and vesicles are associated only with coxae I and nerets, a plesiomorphic number for the Ill. Mygalomorphae, it lacks other unequivocally plesiomorphic characters of the Liphistiidae. There­ fore, unless a reversal is hypothesized several al­ ternatives are possible and few are parsimonious. DISCUSSION A reversal is more parsimonious but only if the Buxton (1913) sectioned the spiders of nine reacquisition of a complex gland and associated mygalomorph genera (as given by Buxton) of four ducts is treated as a single character. There are far families: an unidentified theraphosid genus; two too few data yet to definitively proclaim anything, species of Rlzeclzostica (as Eurypelma rusticum Simon, as Anderson (1973) also concluded. More attention 1890 and Dllgesiella lzentzi (Girard, 1854)), needs to be given to , Atypidae, and Ellrypelma (=Euatlzllls) vagans (Ausserer), Hapaloplls Mecicobothriidae-taxa that are putatively basal on pentaloris (Simon, 1888) and Isclznocolus in the a mygalomorph (Raven 1985; Goloboff Theraphosidae; Neocteniza mexicana F.G.P.-Cam­ 1993). bridge, 1897 (); Isclznotlzele (Dipluridae); The presence of outlets on coxae III and/or on and affinis (Eichwald, 1830) (Atypidae). coxae I in mygalomorphs (as in Isclznotllele) does Later, he (1924) also sectioned Liplzistius batuensis. not falsify Platnick and Gertsch's (1976) hypothe­ Buxton found that all of those genera, save sis. However, the outlet in coxae Il in Bymainiella Isc!motlzele, have coxal gland outlets on each of terraereginae indicates that the hypothesis concern­ coxae I and Ill. Isclznotlzele has coxal gland outlets ing coxal glands must be re-framed. In Atrax only on coxae I (Buxton 1913). Todd (1942) found (Macrothelinae, the putative sister group of the similarly that (=Misgolas, Idiopidae), Hexathelinae: Raven 1980) only two outlets are Hexatlzele and Porrlzotlzele (Hexathelidae), Aparua present. Therefore, unless the hypotheses of Raven (=, ) and () (1980) and of Platnick and Gertsch (1976) are false, have coxal gland outlets also on coxae I and Ill. then the second coxal gland outlet was lost more Totally thus far, 15 mygalomorph genera have been than once - a quite unparsimonious alternative. studied since Buxton (1913), prior to which results Another possibility, if Platnick and Gertsch (1976) were inconsistent. are correct, is that the two-outlet conditions in The occurrence of a third coxal gland outlet in a Mesothelae and most mygalomorphs are not ho­ mygalomorph spider raises a number of questions, mologous. Alternatively, their cladogram may be but the occurrence of three states varying from the incorrect, in which case the Mygalomorphae may most plesiomorphic state known for spiders (as in be polyphyletic - a highly unparsimonious and B. terraereginae) to a third but apomorphic state (as readily falsifiable alternative. in Isclznotlzele) simplifies those questions. The third Because coxal glands of only 15 genera of seven coxal gland outlet must be regarded as the most families (out of 16 families and 263 genera) are plesiomorphic condition in the arachnids by out­ known broad conclusions about the phylogenetic group comparison with the Xiphosura, which have significance of coxal glands in mygalomorph spi­ four outlets. Also, in Heptatlzela, Yoshikura (1955) ders are not warranted. When the coxal glands of reported that mesodermal ducts, ectodermal exit more mygalomorph taxa are known I suggest that ducts and paired coelomic end sacs, the origins of they will be of low informative value to classifica­ coxal glands, arise in the coxae of the palp and legs tions. An alternative IS that the polyphyletic nature I-Ill. The palpal sacs degenerate after hatching. The of a number of mygalomorph families is obscuring sacs in legs I-Ill are associated with ectodermal an otherwise informative pattern. Finally, Buxton ducts but the duct on leg Il later closes leaving the (1913) suggested that the reduced coxal glands in common condition in mygalomorphs. [The puta­ lscllllotlzelc had developed because much of the ex­ tive sister group of spiders, the Amblypygi, are cretory products are utilised in the production of known to have only one outlet or two, as in most silk for the expansive webs. If valid, many 70 R.J. Raven

Figures 2-4 Bymainiella terraereginae, prosoma, sagittal section: 2, Maxillae to coxae Ill, coxal glands discharging onto posterior edge of coxae I and 11 (arrows); 3, 4 Coxal gland outlet and exit tubule on coxae I (3) and coxa 11 (4). Abbreviations: A, artery; CL, coxal labyrinth; ET, exit tubule; M, muscle; MD, midgut diverticula, lateral branch; N, nerve; NC, nephrocytes(?); 0, outlet; S, saccule; V, vesicle. ------

Mygalomorph spider coxal glands 71

Ischnothelinae and the long spinnereted Oiplura­ Buxton, B.l-l. (1917). Notes on the anatomy of arachnids like genera should also have reduced coxal glands. The coxal glands of the arachnids. JOllrllal The extra outlet in Bymainiella terraereginae is not Morphology 29: 1-25. a result of the immaturity of the specimen because Buxton, B.H. (1924). Notes on the internal anatomy of the sectioned individual was subadult (see Materi­ Liphistius batuensis Abr. Journal of the Malayan Branch al and Methods). Juvenile stages are effectively em­ of the Royal Asiatic Society 2: 85. bryological in some characters. However, although Forster, RR (1966). The spiders of New Zealand. Part 1. the specimen here sectioned was within two Otago Museum Bulletin 1: 1-124. moults of maturity, independent evidence suggests Gabe, M. (1968). Caractere cytologiques et that some embryological conditions of the coxal histochimiques de la glande coxal des Araneides. glands are no more plesiomorphic than that of the Compte rendus hebdomadaire des seances de I'Academie mature spider. Schimkevitch and Schimkevitch des sciences, Paris D266: 1142-1144. (1911) were able to discern only one coxal gland Goloboff, P.A. (1993). A reanalysis of mygalomorph outlet in segment III of the embryo of IscJmocolus spider families (Araneae). American Museum Novitates and yet Buxton (1913) found that has 3056: 1-32. outlets on segments III and V (coxae I and III). That Kaestner, A. (1968). Invertebrate zoology. Schimkevitch and Schimkevitch (1911) could not Relatives, Chelicera ta, Myriapoda. Interscience see an outlet on segment V may indicate that their Publishers, New York. entire observation was doubtful. However, I con­ Lopez, A. (1983). Coxal glands of the genus Metepeira sider that if more than two outlets were present, it (Araneae: Araneidae). Journal ofArachnology 11: 97-8. is highly unlikely that they would have seen only Marples, B.J. (1968). The hypochilomorph spiders. one. Proceedings of the Linnaean Society of London 179: 11­ 31. Millot, J. (1933). Vide Bristowe (1933). ACKNOWLEDGEMENTS Petrunkevitch, A. (1933). An inquiry into the natural I am grateful to Or Valerie Todd Davies, classification of spiders, based on a study of their Queensland Museum, for stimulating my interest internal anatomy. Transactions of the Connecticut in this study and for critical comment throughout Academy ofArts and Sciences 31: 299-389. it, to B.J. Marples, England, Professor P. Palmgren, Platnick, N.!. and Gertsch, W.J. (1976). The suborders of Finland, Drs RR Forster, Otago Museum, New spiders: a cladistic analysis (Arachnida: Araneae). Zealand, EA. Coyle, Western Carolina University, American Museum Novitates 2607: 1-15. Cullowhee, Norman I. Platnick, American Muse­ Raven, RJ. (1976). A new spider of the genus Hexathele um of Natural History, New York, and Or B.G.M. Ausserer (Dipluridae: Mygalomorphae) from Jamieson, University of Queensland, for comments Australia. Proceedings of the Royal Society of on this work and previous drafts of this manu­ Queensland 82: 53-61. script. I am most grateful to Mr John Casey, for­ Raven, RJ. (1980). The evolution and biogeography of merly of the Zoology Department, University of the mygalomorph spider family Hexathelidae Queensland, Brisbane, who with the facilities of (Araneae, ). Journal of Aracllllology 8: 251­ 66. that department and the kind co-operation of Or B.G.M. Jamieson prepared and fixed the critical Raven, R.J. (1985). The spider infraorder Mygalomorphae (Araneae): cladistics and sections of Bymainiella terraereginae. Or Lester Can­ systematics. Bulletin of the American Museum of non, Queensland Museum, kindly advised me on Natural History 182: 1-180. sectioning techniques. For all of that I am very Schimkevitch, L. and Schimkevitch, W. (1911). Ein grateful. Beitrag zur Entwicklungsgeschichte der Tetrapneumones. Bulletin of the Academy of Science St. Petersburg (6) 5: 637-654, 685-706, 775-790. REFERENCES Todd, V.E. (1942). The New Zealand Mygalomorphae. Anderson, D.T. (1973). Embryology and Phylogeny in Systematics and Anatomy. M.sc. thesis, University of Annelids and . Pergamon Press, Sydney. Canterbury, Dunedin, New Zealand. Bristowe, W.s. (1933). The liphistiid spiders with an Yoshikura, M. (1955). Embryological studies on the appendix on their internal anatomy by J. Millot. liphistiid spider Heptathela kimllrai. 11. Kumamoto Proceedings of the Zoological Society of London 1932: Journal of SCIence B (2): 1-86. 1015-1057. Buxton, B.H. (1913). Coxal glands of the arachnids. Zoologische Jahrbiicher. l. Abteilwlg fi!r Anatomie lmd Manllscript received 25 February 1994; accepted 2 Allgust Ontologie der Tiere 37: 231-82. 1994.