Australiatelura eugenanae, Smith, 2016

Smith, Graeme B., 2016, On some Silverfish Taxa from Tasmania (Zygentoma: Lepismatidae and Nicoletiidae), Records of the Australian Museum 68 (2), pp. 45-80 : 53-57

Australiatelura eugenanae n.sp.

Figs 42–78

Type material. Holotype: ♂ ( HW 0.93) ( ANIC 5-000047 on two slides) TAS: Eugenana Arboretum, 41.23°S 146.30°E, 29.iv.1987, L. Hill, under several stones, pasture edge by Eucalypt forest with Amblyopone australis Erichson, 1842 and Pheidole sp. [ FORMICIDAE ]. Paratypes (3♂♂, 2♀♀): ♂ ( HW 0.78) ( ANIC 5-000048 in alcohol) same data as holotype; ♀ ( HW 0.83) ( ANIC 5-000049 on two slides) same data as holotype; ♂ ( HW 0.83) ( ANIC 5-000050 on two slides) same data as holotype; ♀ ( HW 0.78) ( TMAG F 14808 in alcohol) Eugenana Arboretum, 41.22556°S 146.30208°E, 17.xii.2012, S. Bunton, beside “White Gum Grove”, under stones; ♂ ( HW 0.63) ( TMAG F 14809 in alcohol), same data as previous.

Other Tasmanian material examined (2♂♂, 5♀♀): ♀ ( HW 0.90) (K 377679 in alcohol) TAS: Friendly Beaches , 24.i.1987, G. Smith and L. Wheeler, edge of beach with Rhytidoponera tasmaniensis Emery, 1911 and Pheidole sp .; ♀ ( HW 0.70) ( AMS K 377704 in alcohol) same data as previous ; ♀ ( HW 0.83) (K 377688 in alcohol) TAS: Friendly Beaches , 41°59'20.8"S 148°17'14.8"E, 31.v.2011, S. Bunton ; ♂ ( HW 0.73) (K260972 K260973 on two slides) TAS: Bicheno lookout, 41.87757°S 148.30612°E, 64 m asl, 19.xii.2011, G. Smith and S. Bunton, under granite stones with ants ; ♀ ( HW 0.73) (K 377693 in alcohol) same data as previous ; ♀ ( HW 0.68) (K 377695 in alcohol) same data as previous ; ♂ ( HW 0.55) (K 377698 in alcohol) same data as previous .

Non-Tasmanian material examined (1♂, 2♀♀): ♀ ( HW 0.90) (K 377677 in alcohol) VIC: Wilson’s Promontory, Telegraph Saddle, 23–24. iv.2013, G. Smith, under stones with ants in dense scrub ; ♂ ( HW 0.75) (K261118 K261119 on two slides) same data as previous ; ♀ ( HW 0.80) (K261120 K261121 on two slides) same data as previous .

Diagnosis. This species is distinguished from other species in the genus by a combination of characters including its short terminal filaments, the length and number of abiesiform notal macrochaetae, the shape and chaetotaxy of the notch of urotergite X and the absence of obvious laminar pulvillae on the pretarsus. In the male it is further distinguished by its wide parameres and more numerous modified pegs at the base of the cerci.

Description. Appearance. In life uniform golden colour ( Fig. 42 ), alcohol preserved specimens off-white. Small to medium size, typical ateluriform shape (tear-drop shape tapering strongly posteriorly) ( Fig. 43 ).

Body length. About 2.8 times longer than wide (range 2.4–3.2); small to medium size, H+B 4.85 mm in largest specimen examined), range of HW 0.63–0.93 mm; head hypognathous ( Fig. 44 ), antennae incomplete in most specimens, but when complete about 0.32–0.38 H+B; cerci mostly incomplete but quite short although possibly relatively longer on smaller specimens, longest measured cercus 0.15 H+B, surpassing apex of urotergite X by less than the length of the tergite; median dorsal appendage damaged in all specimens, longest surviving section 0.21 H+B.

Scales. Of variable shape but mostly rounded or pointed apically, multi-radiate with about 12–22 rays, the rays of the dorsal scales ( Figs 45, 46 ) not or only slightly extending beyond the margins but rays on the ventral scales distally free for about one tenth their length ( Fig. 47 ); scales lacking from head and its appendages, from the legs (although present on coxae), paramera, cerci and median dorsal appendage and ovipositor (present on subgenital plate).

Macrochaetae. Simple or apically bifurcated, some on median dorsal appendage with very strong apical bifurcations, those on posterior margin of tergites abiesiform about 90–120µ in length in larger specimens ( Fig. 48 ) or on average 1.37 times the length of adjacent scales (range 1.00–1.65).

Head. More or less free, only just covered by prothorax at hind margin (possible preservation effect), vertex with scattered small, fine setae as well as distinctly stronger macrochaetae in about four transverse rows, the rows becoming less distinct anteriorly where the setae become smaller and more numerous ( Fig. 49 ). —Labrum with a few fine setae. —Antennae incomplete in all type specimens, longest surviving paratype with antenna 0.22 times H+B (ANIC 5-000049 ♀) ( Fig. 50 ) with at least 11 flagellar intervals. Antennae of specimens from Wilsons Promontory with 12 or more flagellar intervals and up to 0.38 H+B. Pedicel of adult male ( Fig. 51 ), with a shallow fovea in the proximal half on ventral face with several short setae within or on the margins of the depression. Intervals beyond 6th to 7th divided into two annuli, with further subdivisions becoming apparent beyond the 9th to 11th intervals; scape with rosette of macrochaetae apically and several along ventral face, pedicel with a delicately bifurcate macrochaeta longer and stronger than others in the subapical rosette and several shorter setae along ventral face, first annulus of flagellum with eight trichobothria, subsequent annuli/intervals up to 9th to 11th with two trichobothria located on the most distal annulus of each interval, more distal intervals with just one trichobothrium; last interval lost in all type material but specimen from Wilsons Promontory has the typical apical papilla. —Mandibles ( Figs 52, 53 ) with well- developed incisor and molar regions. —Maxilla ( Fig. 54 ) with lacinia just slightly shorter than the galea; lacinia with simple pointed apex, pectinate prostheca just extending beyond tip of lacinia; galea single low broad apical conule ( Fig. 55 ). Maxillary palp stout, with three feathered papilla distally ( Fig. 56 ); apical article of palp 3.6–3.7 times longer than wide with sub-parallel sides, almost 1.5–1.7 times longer than penultimate article and slightly thinner. —Labium with widely rounded posterolateral margins ( Fig. 57 ); ultimate article of palp truncated ovate about 1.11–1.33 times as long as wide with usual six sensory papillae distally; all articles including base with many smaller and a few somewhat stronger setae.

Thorax. Large, about 0.36–0.42 H+B, nota strongly arched forming cavity within which the legs may be held; all nota ( Figs 58–60 ) with submarginal posterior row of 21–28 subequally spaced abiesiform setae with somewhat acute apices ( Fig. 48 ) with about ⅓–½ their length surpassing the posterior margin of the nota; lateral margins of nota with curved setae (about 1¼–1½ times the length of the abiesiform setae) as well as smaller straight setae, the most posterior seta on each side much larger than others being about twice the length of the abiesiform setae; disc of nota with scattered short, delicate setulae among the scales. Prothoracic nota longer than each of meso- and metanota but not as long as both together.

Legs typical ( Fig. 61 ) for genus, tibia L/W ratio of legs PI 3.3 (range 2.9–4.0), PII 3.2 (2.8–3.6), PIII 3.1 (2.5–3.5); tarsi L/W ratio PI 6.4 (5.1–7.3), PII 6.4 (5.6–7.1), PIII 7.9 (7.0–9.5). coxa large and flat with some scales and long setae along the lateral margins; femur with one strong, fairly robust deeply bifurcated sub-lyriform macrochaeta sub-distally on anterior edge and two (or three) longer macrochaetae (the more proximad one thicker and slightly spindle-shaped, the other (two) almost twice as long and tapering) on raised angle of ventral posterior margin; tibia with three robust subdistal lyriform macrochaetae, ventral posterior margin with two stronger stout macrochaetae about ¼ the distance back along the tibia from the distal end and some smaller but still robust setae more distally as well as two strong macrochaetae a bit more than ⅓ the length of the tibia from its proximal end, one almost on the posterior/ventral margin, the other submarginally above, and at the same level, one stout macrochaeta on the ventral face near the anterior-dorsal margin plus the usual apical spine; tarsi of four distinct articles; pretarsus with two quite long and slender, simple, curved, smooth lateral claws and a shorter, sharp erect medial empodial claw, apparently lacking pulvillae ( Fig. 62 ).

Abdomen. All urotergites wrap around the sides of the body with a distinct fold or carina at the most lateral part, making specimens difficult to dissect without tearing the paratergites at this fold and even more difficult to lay out flat ( Fig. 63 ). The consistency of tearing suggests that there is a suture at this point however it is not visible through the scales, the fold is quite severe on all anterior segments forming longitudinal hollows on the anterior segments below each side of the abdomen where they overlap the urosternites; these hollows presumably offer some protection to the legs when required; the margin of each paratergite with several setae between the outer-most macrochaeta and the edge of the urotergite ( Fig. 64 ), however because of the fold these setae are actually located medial and ventral to the largest lateral macrochaeta of each segment ( Fig. 65 ); urotergites I–IX with submarginal rows of 5–25 abiesiform setae similar to the thorax, progressively decreasing in number posteriorly, posterolateral corners of urotergite IX produced into subtriangular posterolateral lobes that also wrap around tightly and are prone to tearing at a predetermined line, but in contrast to the more anterior urotergites this line is mediad to the largest lateral seta ( Fig. 66 ), five to six submarginal abiesiform setae along the medial posterior margin as well as one abiesiform seta mediad but adjacent to the large posterolateral macrochaeta. Urotergite X ( Figs 67, 68 ) with 1+1 strong macrochaetae on the acute posterior corners with a deep V-shaped insertion between the apical macrochaetae which generally, in older specimens of both sexes, does not have a very rounded medial “corner; the notch is less noticeably deep and acute in younger specimens and not very different to that of Au. tasmanica ; the inner margin of the notch has one to three short apically cleft setae and the outer margins have one to three setae near the apex. Underside of urotergite X in mature males with 1+1 elongated fields of about 20–30 modified sclerotised setae or pegs ( Fig. 69 ).

Urosternites ( Fig. 70 ) much less wide than urotergites; urosternite I glabrous or with a single very small medial seta; II with two very small submarginal setae medially on a slightly convex margin as well as 2–4 setae on the posterolateral margins; III with small medial styli and small 1+1 submarginal setae between the stylus and small sensory setae adjacent to the base of the styli, 4–6 setae on each posterolateral corner; IV–VII with small lateral styli and 1+1 submedial erect macrochaetae and 1+1 smaller setae lateral to these as well as three to seven setae on posterolateral corners; VI also with large eversible vesicles with five or six simple setae on face of vesicle ( Fig. 71 ), VII with pseudovesicles, urosternite VIII in male entire ( Figs 72, 73 ) with posterior margin between the styli protruding slightly and about ten setae along its posterior margin; urosternite IX in male divided into separate coxites with broad apically rounded parameres reaching to about half the length of the styli, 1.72–2.15 times longer than wide ( Figs 73, 74 ). Penis small, largely hidden by parameres, with narrow opening surrounded by small setae on tubercules ( Fig. 74 ). Urosternites VIII in female divided into separate coxites with subtriangular subgenital plate also with styli and lateral macrochaetae ( Fig. 75 ); urosternite IX in female also divided into separate coxites with larger styli (almost twice as long as those on other segments); ovipositor ( Fig. 75 ) moderately bulbous with ten divsisions, apices of all gonapophyses produced into small triangular processes, ultimate divisions of posterior gonapophyses with two long setae, penultimate division with field of small hooked setae.

Cerci incomplete in most specimens but fairly short (extending beyond the apex of urotergite X, excluding the macrochaetae, by no more than the length of urotergite X), with eight or nine divisions, divisions from fourth divided into annuli, basal division longer than second division, setae and trichobothria as in Figs 68 and 76 ; cerci in mature males with sensory pegs on inner ventral surface ( Figs 68, 69 ); one or two large and one small peg on the basal division, two to five large and zero to two smaller ancillary pegs on the second division, third division usually without pegs although one specimen (K260973 from Bicheno) has a single large peg on division three on just one of its cerci; median filament incomplete in all type specimens ( Figs 77, 78 ), specimens from Bicheno and Wilsons Promontory with eight or nine divisions, the basal three or four entire, and further pseudo-subdivided into annuli from the seventh or eighth division; similar in males and females, i.e. lacking modified spines.

Juvenile stages: one ♂ (HW 0.55) (K377698) already had pegs developed on its cerci.

Biology. Panmyrmecophilic, collected under stones with ants in forest or on the edge of pasture. Host ant species include Amblyopone australis Erichson, 1842 , Myrmecia esuriens Fabricius, 1804 , Pheidole sp. and Rhytidoponera tasmaniensis Emery, 1898 . Not all host ants have yet been identified.

At several locations both Au. eugenanae and Au. tasmanica were collected in the same collection tube. Because specimens found under several stones within a few metres of each other were bulked into the same collection tube, it is not known whether these two species were in the same or separate ant nests.

Etymology. The species is named for the type locality of Eugenana.

Remarks. While determination of mature males is fairly straight forward due to the wide parameres, short cerci and the more complex arrangement of pegs on the cerci, determination of the juveniles and females is more uncertain. Both Tasmanian Australiatelura species have been found under the same or adjacent stones possibly within the same ant colony. Some doubt exists regarding the determination of female specimens in the material examined, especially when smaller and if they have not been mounted on slides. Females identified as Au. eugenanae were found together with males of Au. eugenanae and have a body size greater than the normal range of Au. tasmanica or were large, with distinctly shorter terminal filaments and/or with the medial angle of the notch fairly acute, not distinctly rounded. The allocation of the very small juvenile Australiatelura specimens to species is even more suspect.

Australiatelura eugenanae appears to be closer to Au. michaelseni (Silvestri, 1908) or Au. kraepelini (Silvestri, 1908) , both of which were described from Western Australia. Australiatelura michaelseni is only known from female specimens which appear to have similarly short terminal filaments, long slender lateral claws of the pretarsus, a reasonably acute notch on urotergite X and quite long abiesiform macrochaetae but from Silvestri’s illustrations it has a larger rounder subgenital plate, the valves of the ovipositor do not appear to have the pointed apices, there are strong setae along the whole length of the inner margin of the notch of urotergite X and the base of the lateral claws of the pretarsus is surrounded by a short obtuse laminar process. Silvestri’s original description and illustrations are by no means adequate, especially due to the lack of a male specimen. Womersley (1939) illustrated the male genitalia of a specimen which has short terminal filaments and broad parameres similar to Au. eugenanae . This illustration is labelled “16. J. Male genitalia” without explicitly nominating the species but this is almost certainly a typographical error and the illustration refers to male specimens from Mallacoota in southern NSW which he believed represented Au. michaelseni illustrated in his Figs 16 G–I . Reference to Silvestri’s type specimen of Au. michaelseni could give supporting evidence that the abiesiform macrochaetae are long but cannot answer the question regarding the shape of the parameres. New topotypical material from WA which included a male could be useful in resolving this question.

Australiatelura kraepelini was described using both male and female specimens. It appears to have quite long abiesiform macrochaetae, the paramera of the males are wider than those of Au. tasmanica but not quite as wide as those of Au. eugenanae . The subgenital plate is about the same size as that of Au. eugenanae but more rounded than sub triangular, however this can be an artefact of the way the specimen is observed. Australiatelura kraepelini differs from Au. eugenanae in that it, like Au. michaelseni , is reported to have laminar processes at the base of the lateral claws and a long series of strong setae on the inner margin of the notch of urotergite X. Silvestri made no mention of conical processes at the base of the cerci however he also overlooked these with Au. tasmanica so the types of Au. kraepelini should be checked. Australiatelura kraepelini also seems to have much longer antennae but as mentioned under the remarks for Au. tasmanica , antennal length can be quite variable.

The finding of Au. eugenanae on both the Australian mainland and in Tasmania is not unexpected as the two have been connected many times over the last 2 million years, most recently only 20, 000–10, 000 years ago.

Figures

Figure 42. Australiatelura eugenanae n.sp. Wilsons Promontory.

Figures 43–62. Australiatelura eugenanae n.sp. (43) habitus, dorsal; (44) habitus ♀, lateral; (45) dorsal scale; (46) dorsal scale; (47) ventral scale; (48) scale and abiesiform macrochaeta of metanotum; (49) head; (50) left antenna; (51) idem, ♂ pedicel; (52) mandible, (53) idem, molar and incisor regions; (54) maxilla (larger setae only); (55) idem, lacinia and galea; (56) idem, apex of maxillary palp; (57) labium; (58) pronotum; (59) mesonotum; (60) metanotum; (61) PIII (larger setae only); (62) idem, pretarsus. Scale bars = 0.1 mm.

Figures 63–74.Australiatelura eugenanae n.sp. (63) urotergite II, with paratergite partially detached at presumed suture; (64) urosternites IV and V, showing overlap of paratergites; (65) anterior urotergite, lateral chaetotaxy, smaller setae on paratergite lying below; (66) urotergite IX, with detached paratergite; (67) urotergite X of female; (68) urotergite X of male and base of cerci; (69) pegs on cerci and pegs beneath urotergite X (latter drawn through the tergite); (70) urosternites I–VII; (71) vesicles and stylus of urosterniteVI; (72) posterior margin of urosternites VII and VIII of male; (73) urosternites VI–IX with parameres, styli and base of median dorsal appendage (drawn in alcohol before mounting); (74) coxites IX and parameres after slide mounting. Scale bars 0.1 mm.

Figures 75–78.Australiatelura eugenanae n.sp. (75) ♀ ovipositor,coxites VIII and subgenital plate;(76) cercus of ♀ (ANIC 5-000049); (77) median dorsalappendage ♀ (ANIC 5-000049); (78) base of median dorsal appendage of ♂ (ANIC 5-000050). Scale bars 0.1 mm.

Figures 2–18. [see caption on facing page, p. 49]