Marples, B.J.

Pacific Science

Marples, B J

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Pacific Symphytognathid Spiders

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Pacific Symphytognathid SpidersB.]. MARPLESlTHE FAMILY SYMPHYTOGNATHIDAE was erect-ed by Hickman (1931) for a minute spider,Symphytognatha .globosa, from Tasmania. Themost characteristic feature is the absence oflung-books, the anterior spiracles leadinginto tracheal tubes which supply the cephalo -thorax as well as the abdomen, while theposterior spiracles are absent. In S. globosa thefemale has no palps. Fage (1937) and Gertsch(1941) have transferred several other generainto this family, or described new ones . Insome of these only four eyes are present in-stead of the usual six, and the female palpsmay be merely reduced in size instead of ab-sent.Some of the specimens described in thepresent paper werecollected in 1946 in Upolu,Western Samoa, during a visit devoted tothe collection of arachnids; a few hours ofcollecting in Suva, Fiji, on the return journey,yielded specimens of a closely related butquite distinct species. Because this is a pe-culiar and interesting family which has notpreviously been recorded from the Pacific is-lands, it seemed desirable to deal with bothspecies together. The main Samoan collectionis being dealt with as a whole .In the following descriptions the leg index,given below the leg formula, is the length ofthe leg divided by the length of the carapace.The tibial index is the breadth of the proximalend of the patella expressed as a percentage ofthe combined lengths of the tibia and patella.Patu gen. nov.Six eyes. Chelicerae fused for about half of-Professor of Zoology, University of Otago, Dune-din, New Zealand. Manuscript received, March 28,1950.their length. Ventral end of the retromarginof the cheliceral groove with a large bifurcatedprocess . Palp of female absent. Three claws,ventral one large. Abdomen pear-shaped withventral spinnerets, Close to genus Symphytog-natha, but different in.web and coccoon andin a number of minor structural characters.Genotype: Patu oitiensis.P"tu vitiensis n. sp.Three v, 1cJ'I, 1 immarure o". From treetrunks, Suva, Fiji.FEMALE: Length 1.20 mm. Carapace, ster-num , and mouth parts brown, legs lighter.Abdomen mottled greyish-brown above,darkening towards the posterior end. Ventralsurface behind the spinnerets very muchlighter, almost cream-coloured.Carapace: Length 0.37 mm., breadth 0.32mm. Highest near the eyes, which are near theanterior margin.Eyes: Six, all pale. Posterior row recurved.Lateral eyes touching. PME separated fromone another by one quarter of their diameterand from the PLE by rather more than theirdiameter. Ratio of eyes PLE:ALE:PME =71:68:60. Eye group breadth 0.23 mm .Chelicerae: No boss or stridulating organ.Apparently fused for rather less than half oftheir length. Fang stout with relatively largeserrations, and longer than the groove. Theventral retromargin of the groove with astout process bifurcated into two blunt teeth .Maxillae: Converging but not meetingabove the lip.Lip: Broader than long.Sternum: Length 0.23 mm ., breadth 0.22mm . Convex. .Paip: No vestige visible even in cleared(47)48 PACIFIC SCIENCE, Vol. V, January, 1951seen in a cleared specimen as in the figure .Pair of striated structures on the pedicel as inS. globosa, where they were interpreted byHickman (1931) as lyriform organs and byPetrunkevitch (1933) as stridulating organs.4 232.8 2.6 2.11Legs:--- - - - -2.9specimens, though a stout hair arises in thesame spot.0.35 0.37 0.21Q31 Q35 Q140.28 0.24 0.08Q35 Q35 Q14Tibial Index IV 13.6I. .II. .III. : .IV .Tibial Index I. 13.1FEMURPATELLAAND TIBIA METATARSUS TARSUS0.190.190.170.21TOTAL1.120.990.771.05Three claws, the median one being long,sharp and downcurved, and larger than thepaired ones. The median claw on legs I and IIhas one tooth; all the other claws are withoutpectinations. A few serrated bristles on thefeet. No spines, but a large erect bristletowards the distal end of each patella, twosmaller ones on tibia I, and one on tibia II.One trichobothrium on metatarsi I and II,three on tibiae I and II , two on III, and fouron tibia IV.Abdomen: Length 0.88 mm ., breadth 0.56mm. Pear-shaped with a rounded posteriorend. The six spinnerets are ventrally placed,the anterior being the largest. Anal tuberclewidened transversely. No colulus . Epigyne inthe form of a transverse furrow overhung fromin front by a rounded lip . Internal structureMALE: Length 0.76 mm . Carapace, sternum,and mouth parts brown, legs light brown.Abdomen light yellowish-brown, posteriorend black. Anterior part of the sides slightlydarker ; there being a very faint suggestion ofa dorsal band joining these areas. More wellmarked are two triangular dark areas anteriorto the posterior black cap. Together theyform a procurved crescentic dark marking,interrupted in the mid-dorsal line by theyellowish .brown ground colour of the ab-domen.Carapace: Length 0.30 mm., breadth 0.31mm. Sloping up steeply to the conspicuousrow of eyes. Anterior to the eyes is a sinuousridge, concave above the chelicerae and curv-ing forward in the middle line. This has theappearance of being the anterior edge of theb c~00'b06J ,h,.'e fFIG. 1. Pat« oitiensis: a, female , ventral view; b, male, left side ; c, female chelicera, dorso-retrolateral view;d, female apparatus as seen in a cleared skin; e, male palp, retrol ateral view; f, male palp , ventral view.Symphytognathid Spiders-MARPLEScarapace, but below it is a more or less verti-cal clypeus. The details are very difficult tomake out, owing to the small size.Eyes: Six, all pale. Posterior row slightl yrecurved. The PME are separated from oneanother by about half their diameter and fromthe PLE by almost thei r diameter. The lateraleyes are touching. Ratio of eyes, PLE:PME:ALE= 75:70:51. Breadth of eye group 0.23mm. The PM E are separated from the an-terior ridge by about half their diameter aridfrom the anterior edge of the carapace byabout two and a half times their diameter.Chelicerae: Small.Maxillae and Lip: As in female.Sternum: length 0.24 mm ., breadth 0.19 mm.Palp: Large and rounded palpal organ, de-tails as in figure.1 2 4 3, Legs:--------3.8 3.3 2.7 2.449Patu samoensis n. sp.Eight 9 from minute sheet webs in the ir-regularities of tree trunks in forest , Apia,Upolu, Western Samoa.FEMALE: Lengt h 1.63 mm . Carapace, ster-num, and mouth parts dark brown. Legslighter with dark annulations. Abdomenmottled greyish .Carapace: Length 0.55 mm. , breadth 0.43mm . High and rounded.Eyes: Six, all pale. Large and consp icuous,posteri or row straight. PME separated fromone another by less than a quart er of theirdiameter and from the PLE by less than halftheir diameter. Lateral eyes touching. Ratio ofeyes, PME :PLE:ALE= 78:68:64. Eye groupsbreadth 0.30 mm . PME twice their diameterfrom the carapace edge.Chelicerae: Apparently fused for about halftheir length and rather cylindrical in anteriorview. The fang is longer than the groove andPATELLAFEMU R AND TIBIA MET ATARSUS1.. . . . . .. .. . . . . . . . . . . . . . . .. .. 0.31II.. . . . . . . . . . . . . . . . . . . . . . . . . . . 0.26II I. . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.20IV.. . . . . . . . . . . . . . . . . . . . . . . . . . . 0.27Tibial In dex 1. .. , . . 11.3TARSUS0.36 0.16 0.230.33 0.14 0.190. 23 0. 10 0.150.30 0.11 0.16Tibia l Index IV 12.5TOTAL1.060.920.680.84One stout spine on the ventral surface oftibia II about one third of its length from thedistal end.Abdomen: Length 0.55 mm. , breadth 0.33mm. Pear-shaped with the narrower posterior .end truncated. Spinnerets ventral and close tothe petiolus.Web and Coccoons: The webs were sitiIatedon tree trun ks and consisted of fine horizontalsheets about 4 centimeters long. The silk wastoo fine for the arrangement of threads to bemade out. No oblique thread was noticed asin the Samoan species, though a bunch ofcoccoons was hanging some way from theedge. Spiders were seen sitting in the cent reinstead of with thecoccoons ; possibly thesemay have been males while the females werewith the coccoons.has relatively large serrations. On the ventralretromargin of the groove is a sto ut processbifurcated into two sharp teeth. The cheli-cerae do not bulge forward in front of theedge of the carapace when seen in dorsal view.Maxillae: Converging but not meetin gabove the lip .Lip: Broader than long. Junction with ster-num distinct.Sternum: Lengt h 0.30 mm., breadth 0.29mm. Convex.Palp: No trace of a palp is to be seen evenin a cleared specimen, though three or fourhairs arise from the same spot. No palp wasvisible in the cleared skin of a first instar takenfrom a coccoon .1 2 4 3Legs: - --- - - - -2.6 2.4 2.4 1.950 PACIFIC SCIENCE,Vol. V, January, 19510.46 0.26 0.300.43 0.22 0.300.31 0.16 0.220.42 0.24 0.25Tibial Index IV 14.3FEMURI.. . . . . . . . . . . . . . . . . . . . . . . . . . . 0.43II.. . . . . . . . . . . . . . . . . . . . . . . . . . . 0.38III.. . . . . . . . . . . . . . . . . . . . . . . . . . . 0.31IV. . . . . . . . . . . . . . . . .. . . . . . . . . . . 0.42Tibi al Index I 15.8PATELLAAND TIBIA METATARSUS TARSUS TOTAL1.451.331.001.3 3Three claws, the third as large as the dorsalpair and sharply directed downwards. Clawsslender and not pectinated, and pectinatedbristles not present. No spines, but a largeerect bristle at the distal end of each patella,two smaller ones on tibia I and one on tibiaII. One trichobothrium on metatarsi I and II,three on tibiae I and II, two on tibia III, andfour on tibia IV.Abdomen: Length 1.16 mm ., breadth 0.80mm . Pear-shaped, projecting behind in aknob-ended process and provided with a pairof similar dorso-lateral processes. The sixspinnerets are ventral, the anterior being thelargest. No colulus. Anal tubercle large. Theepigyne is visible only when the abdomen isremoved. There is a transverse fold overhungby a backwardly directed lip whose edge isdark and thickened. The appearance of acleared specimen is shown in the figure.In specimens cleared in potash the spiraclescould be seen leading into an atrium fromwhich numerous tracheal tubes supplied boththe cephalothorax and abdomen. There was atransverse connecting tube between the atria.Sections showed five pairs of tracheal tubes,three large and two small, passing throughthe pedicel into the cephalothorax.Weband Coccoon: The webs were spun in theirregularities of a fallen tree trunk. They con-sisted of a very fine horizontal sheet with veryregular meshes. The sheet was an irregularpolygon some 6 centimeters long, and anoblique thread extended upwards from thesheet between 1 and 2 centimeters from oneend. The threads of the sheet radiated fromeFIG. ·2. Patti samoensis: a , female, dorsal view; b, female, left side ; c, female chelicera, dorso-retrolateral view;d, female, eyes, dorsal view; e, female app aratus as seen in a cleared skin ; f, female, ant erior view of carapace andchelicerae.Symphytognarhid Spiders-MARPLESthe point of attachment of the oblique thread,but it was a sheet and not an orb web. Thespider rested at this point together with acluster of coccoons. The coccoons each con-tained only a single egg about 0.34 mm. indiameter. The coccoon consisted of a sphere 'some 0.66 mm. in diameter, woven loosely offine threads so as to be transparent, the wholesurface being covered with spirals of thickthread with the loops projecting from the sur-face. The whole structure was thus 0.83 mm .in diameter. All the silk was white . This isquite unlike the web and coccoon describedby Hickman for S. globosa. A first instar re-moved from a coccoon had a globular abdo -men with no trace of the projections.SUMMARYA new genus of spiders belonging to thefamily Symphytognathidae is described, witha species from Fiji and another from Samoa.Members of this family have been described51from Tasmania; New Caledonia, East Indies,and Central and South America, but apparent-ly not from the Pacific islands . The new genusseems to be close to Symphytognatha fromTasmania.REFERENCESFAGE,1. 1937. A propos de quelques nouvel-les araignees apneumones. Soc. Zool. France,Bul. 62: 93-106.GERTSCH, W. J. 1941. Report on somearachnids from Barro Colorado Island,Canal Zone. Amer. Mus. Nat. Hist. Novi-tates 1146: 1-8.HICKMAN, V. V. 1931. A new family of spi-ders. Zool. Soc. London, Proc. 1321-1328.PETRUNKEVITCH, A. 1933. An inquiry intothe natural classification of spiders, basedon a study of their internal anatomy. Conn.Acad. Arts and Sci., Trans. 31: 299-389 .

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Pacific Symphytognathid Spiders

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