Qantelsella louisae, Smith, 2015

Smith, Graeme B., 2015, New Silverfish Taxa from Queensland (Zygentoma: Lepismatidae), Records of the Australian Museum 67 (3), pp. 67-81 : 68-74

Qantelsella louisae n.sp.

Figs 2–46

Type material. Holotype ♂. ( HW 1.10 ) ( QM T228755 on two slides) Queensland: Bladensburg National Park, Skull Hole, 22.55789°S 143.00044°E 204 m asl, 8.viii.2013, Graeme Smith , in dry leaf litter.

Description

Appearance in life mottled grey with distinct lighter, almost white, scales on sides of head and along both sides of abdomen and margins of urotergite X, legs above darkish grey on tibia and femur with lighter brown tarsi, antennae with darker brown pedicel, flagellum distinctly banded brown and white with the browner bands becoming longer distally, terminal filaments evenly brown ( Fig. 2 ).

Body shape as in Figs 2 and 3 , neither elongate nor broad. Body length 7.3 mm (♂); HW: 1.23 mm; thorax: length 2.4 mm (or 0.33 times H+B); width 1.75 mm widest at the mesothorax; antennae length 6.5 mm (or 0.9 H+B); cerci damaged, maximum preserved length 3.75 mm (or 0.51 H+B); median dorsal appendage broken, maximum preserved length 5.05 mm (or 0.69 H+B). Thorax only slightly wider than abdominal segment I, the following abdominal segments about the same width until the fifth or sixth and only narrowing moderately towards the posterior end.

Base colour white to light brown. Pigment brown and quite dark in places. Antennae annulated with darker brown bands getting proportionately longer distally, scape and pedicel darkly pigmented, caudal filaments more or less evenly brown, although with the hint of lighter area at the distal end of some subarticles. Head with pigment around the eyes and especially across the clypeus and labrum, mouthparts also with pigment especially laterally and palps with pigment on each article, especially distally. Coxae with dark pigment on anterior “shoulders” and along outer margin, trochanter with pigment along posterior margin, femur with pigment darker along margins especially distally and on distal end of dorsal surface, tibia more darkly pigmented with very dark patch at distal end, first article of tarsi pigmented distally, PII and PIII with some light pigment also on other tarsal articles. Urosternites VIII and especially IX, quite pigmented or more heavily sclerotized.

Body well covered with scales which are dark in colour (in alcohol), unevenly rounded, ovoid, distally truncate or even somewhat irregular with notches in the distal margin, with numerous brown subparallel ribs that do not extend beyond the margin ( Fig. 4 ); scales lighter or hyaline along outer margin of urotergites, especially anteriorly. Ventral scales hyaline medially but brown laterad of the combs of macrochaetae. Dark scales also present on pedicel and scape and second and third articles of maxillary palp but not labial palp. Present on top of head and on labium, on all thoracic sterna and all articles of the legs except the last three tarsal articles; also present on more basal articles of cerci.

Macrochaetae quite variable, mostly pectinate, often very dark, almost black but others brown and many hyaline. The degree of pectination varies enormously, from almost smooth with a few small, hardly visible, delicate sharp pectinations to very plumose with long sharp pectinations which give an almost feathery appearance ( Fig. 5 ) which are mostly found on posterior segments and basal articles of terminal filaments. Other macrochaetae are shorter, often thicker and quite stout, almost carrot-shaped, with small pectinations ( Fig. 6 ); these are found mostly associated with the lateral combs, along the margin of the nota and on the legs. Other pectinate macrochaetae are darker with much more rounded apical pectinations ( Fig. 7 ), such as the longer macrochaetae of the combs and lateral margins of the nota and legs. Some macrochaetae look slightly misshapen in their basal half and it is unknown if this is the natural state or related to the mounting medium as noted occurring with some nicoletiid silverfish mounted in the same way ( Smith et al., 2012).

Head ( Fig. 8 ) wider than long, with macrochaetae along the anterior and lateral margins of the head and over the anterior margin of the eyes, generally this marginal row is only one to two macrochaetae wide although there are areas three to four macrochaetae wide on the anterolateral corners of the head; with 1+1 long, thin setae sublaterally on each side just posterior to the antennae and two strong macrochaetae behind the eyes on each side. Clypeus with 1+1 macrochaetae immediately anterior to the frons suture and 1+1 fields of about 14 macrochaetae more anteriorly. Labrum with a band of strong macrochaetae across the proximal quarter and additional small setulae distally. Eyes dark brown. —Antennae: scape ( Fig. 9 ) quite long with short, robust, weakly pectinate setae subapically, pedicel shorter (0.42 length of scape) with subapical rosette of short, strong, weakly pectinate setae and several cilia, third article shorter with a few short setae and two trichobothria, fourth article shorter with some setae and three trichobothria, articles five to seven progressively a little longer with setae, three trichobothria and one to three cilia, article eight weakly subdivided into two subarticles, the basal portion without chaetotaxy, the distal portion with setae, two trichobothria and four quite long cilia (almost as long as the short trichobothria), first pigment band on article nine, subsequent articles with similar chaetotaxy, subarticles further dividing from article 11 with trichobothria only present on the ultimate subarticle. Small circular sensillae appear from about one quarter of the length of the flagellum, becoming larger and easier to see in the more distal articles ( Fig. 10 ), although much harder to locate on the heavily pigmented articles. They appear to be present on most subarticles although not on all. These sensillae, difficult to observe under an optical microscope, are almost circular with a raised perimeter ridge without any obvious structure emerging from within the ridge. They are probably poculiform sensillae (see electron micrograph in Irish & Mendes, 1988 p. 281 fig. 1), however, in several examples, the lip appears to be extended distally so that they resemble scutelliform sensillae (see Irish & Mendes, 1988, p. 281, fig. 5). New material and electron microscopy is required to clarify the nature of these sensillae. Rod-like basiconic sensillae also appear on the most distal subarticles in the distal half of the antennae but only in small numbers (two?). Trichobothria absent from all articles in last third of flagellum. —Mandibles ( Figs 11, 12 ) typical for Ctenolepismatinae with well-developed molar and incisor regions; a group of eight or nine strong, apically bifurcated but simple, setae distally adjacent to the molar area and a bush of about 40 strongly pectinate macrochaetae and setae externally. —Maxilla ( Figs 13–15 ) with four pectinate macrochaetae externally proximal to the palp, the lacinia with three teeth, one shorter than the rest, followed by about nine lamellate processes and a row of four apically bifurcate setae; ultimate article of maxillary palp 2.9 times longer than wide and 1.2 times longer than penultimate article, without any obvious papillae or specialized sensillae. Remaining articles with many moderately strong setae and no obviously stronger setae. Last three articles of palp with fine setae and cilia, basal and second articles with subapical coronae of slightly thicker setae. —Labium ( Fig. 16 ) short and broad with rows of short, strong, apically bifurcate setae on the prementum; postmentum with a transverse row of apically bifurcate setae; glossae and paraglossae quite broad with short curved setulae. Labial palp short, ultimate article hatchet-shaped, expanded medially ( Fig. 17 ), ⅓ to ½ wider than long (L/ W 0.66 –0.81) with a long, almost straight row of papillae of the “aufgelöst type ” (11 on one palp, 13 on the other), apparently without other specialized sensillae; covered with numerous fine short stout setae and long fine cilia.

Pronotum ( Fig. 18 ) with setal collar of pectinate macrochaetae in single row. Lateral margins with pectinate macrochaetae as well as three small combs anterior to the first trichobothrial area (respectively with two, three and two macrochaetae of different lengths) and some strong submarginal macrochaetae posterior to this trichobothrial area but not forming obvious combs. Anterior trichobothrial area ( Fig. 19 ) about one third along the margin and the posterior area ( Fig. 20 ) a little further than two thirds along the margin. Posterior margin with 1+1 single pectinate macrochaetae, each associated with two cilia and a marginal setula ( Fig. 21 ). —Mesonotum ( Fig. 22 ) lacking anterior notal collar, lateral chaetotaxy similar to pronotum with five combs each of two macrochaetae anterior to the first trichobothrial area which is located about half way along the lateral margin ( Fig. 23 ); posterior trichobothrial area ( Fig. 24 ) slightly further back than three quarters of the way along the margin; posterior margin with 1+1 single macrochaetae as in the pronotum. —Metanotum ( Figs 25–27 ) similar to mesonotum.

Presternum narrow, with transverse row of very small simple setae ( Fig. 28 ). All thoracic sterna trapezoidal with 1+1 combs of pectinate and smooth setae in the posterolateral corners. —Prothoracic sternum ( Fig. 28 ) large, about as long as wide at its base, anterolateral corners each with a single seta; posterolateral combs of 10–11 marginal or submarginal setae, some strongly pectinate, others almost smooth ( Fig. 29 ), the distance between the combs four to five times the length of each comb. —Mesosternum not well mounted (folded over and pushed against air bubble), similar to other thoracic sterna with 1+1 combs of five or six marginal or submarginal smooth or pectinate setae ( Figs 30, 31 ). —Metasternum ( Fig. 32 ) about 1.2 times wider than long, the posterolateral combs of four to six setae ( Figs 33, 34 ) with the distance between the combs about eight times the length of each comb.

Legs robust and not particularly long, not lengthening strongly posteriorly with tibia III only 1.5 times longer than tibia I. Tibia L/W ratio PI 2.1, PII 2.4, PIII 2.4; tarsi L/W ratio PI 4.4, PII 6.0, PIII 6.6. Leg PI ( Fig. 28 ) with single pectinate macrochaeta laterally on small article between prothoracic presternum and coxa. —Outer margin of coxa with numerous pectinate macrochaetae, forming a comb of five macrochaetae proximally, inner margin with three robust pectinate macrochaetae spaced in the distal half and several simple macrochaetae over the articulation. —Trochanter with some simple and some small pectinate setae. —Femur short and very broad, with one robust pectinate macrochaeta midway along the outer margin and a group of three (?) stout pectinate macrochaetae over the distal articulation; posterior margin with some long pectinate setae and simple setae adjacent to the tibia below and above a row of five or six stout pectinate macrochaetae. —Tibia short and wide with two robust macrochaetae midway along outer margin and some smaller simple setae over the articulation distally; posterior margin with at least two stout macrochaetae in distal half as well as other simple setae; apical spine with several fine setae. —Articles of tarsus with many simple setae and some more robust setae below. —Pretarsus with two strong but simple outer claws and a strong medial empodial claw. —PII and PIII with similar chaetotaxy ( Figs 32, 35 ) but the basal tarsal article is comparatively longer and about equal in length to the other three combined tarsal articles on both PII and PII.

Abdominal chaetotaxy summarized in Table 1. Urotergite 1 with 1+1 lateral combs each consisting of two long submarginal pectinate macrochaetae and two marginal short, stout pectinate macrochaetae with two cilia, one at each end of the submarginal comb. Urotergites II–VIII each with 2+2 combs ( Fig. 36 ), the lateral combs ( Fig. 37 ) similar to those on urotergite I, the sublateral combs ( Fig. 38 ) consisting of just a single, long, pectinate macrochaeta with a cilium on each side and in most cases a small, thickish setula. Urotergite IX glabrous. Urotergite X ( Fig. 39 ) short, subtriangular (L/ W 0.37), without bristlecombs, with a very dense fringe of pectinate macrochaetae, those above more robust with delicate pectinations, those below hyaline with very long pectinations.

Urosternites I–II glabrous and III–VII ( Fig. 40 ) each with 1+1 bristlecombs, composed of two to three long submarginal pectinate macrochaetae with a cilium external to the comb and a small but stout marginal seta with indistinct pectinations ( Fig. 41 ). Urosternite VIII in ♂ entire ( Fig. 42 ), with well-developed stylets, each armed apically with four or five stout but apparently smooth macrochaetae, as well as similar but smaller setae along the ventral face in the distal half. Lateral combs of urosternite VIII composed of four or five, long, pectinate macrochaetae mediad to the stylets and five to six short, stout pectinate macrochaetae on the dorsal surface of the margin either side of the insertion of the stylets.

Genital region of ♂ as in figure 43, the internal process of coxite IX not very long, about 1.2 times longer than wide at its base and about four times longer than the external process. Apex of internal process acute, with numerous strong macrochaetae along both the inner and outer margins; those macrochaetae inserted on the ventral side of the margin smooth or with very inconspicuous pectinations, those inserted dorsally more delicate with very obvious and long, almost feathery, pectinations. Inner and outer margins of outer process with several short, stout macrochaetae with the pectinations more pronounced on those inserted on the dorsal side of the margin. —Penis with numerous short glandular setae apically, each set on a protuberance. Parameres absent. —Stylets IX about 1½ times longer than those on urosternite VIII (excluding the apical macrochaetae), surpassing the apex of the inner process by a little less than the length of the inner process. Stylets armed apically with four or five stout but apparently smooth macrochaetae, as well as similar but smaller setae along the ventral face of the stylet ( Figs 42, 43 ).

Terminal filaments probably incomplete. Basal articles of cerci and median dorsal appendages ( Fig. 44 ) with hyaline feathered pectinate macrochaetae below becoming progressively less pectinate distally until completely smooth in the most distal surviving articles ( Figs 45, 46 ).

Female unknown.

Habitat. In very dry shallow leaf litter on banks of ephemeral creek.

Etymology. The species is named for my wife Louise in appreciation of the many years of support and encouragement to follow my interest in silverfish.

Remarks

The thoracic and abdominal chaetotaxy of Qantelsella resembles that of the Namibian genus Ornatilepisma Irish but its morphology differs in several other characters usually also considered relevant at the genus level (cf. Irish, 1988). These include the cephalic chaetotaxy, especially that of the labrum (row of macrochaetae lacking in Ornatilepisma ), the shape of the thoracic sternites (cordiform or parabolic in Ornatilepisma ), the shape and chaetotaxy of urotergite X (short, rounded trapezoidal with 1+1 posterior combs in Ornatilepisma ), the abdominal stylets (reduced or lacking in Ornatilepisma ) and the number of papillae on the labial palp (only two in Ornatilepisma ). Qantelsella may be derived from an Acrotelsella -like ancestor with a triangular urotergite X and two pairs of abdominal stylets but in many other ways is quite different. The genus Acrotelsella is quite diverse in Australia and much more work is required before its diversity is well enough understood to elaborate any relationship with Qantelsella .

Figures

Figure 2. Qantelsella louisae n.sp.

Figures 3–15. Qantelsella louisae n.sp. holotype ♂ (3) habitus; (4) notal scale; (5) feathery macrochaeta with very long pectinations; (6) stout macrochaeta with fine pectinations; (7) long macrochaeta with rounded pectinations;(8) head;(9) basal articles of antenna;(10) distal articles of antenna showing a circular sensilla (cs) and rod-like basiconic sensilla(rs); (11) mandible;(12) idem, detail of incisor and molar regions; (13) maxilla; (14) idem, lacinia and galea; (15) idem, ultimate article of palp. Scale bar = 0.1 mm unless otherwise indicated.

Figures 16–27. Qantelsella louisae n.sp. holotype ♂ (16) labium; (17) ultimate articles of labial palp; (18) pronotum, right half; (19) idem, anterior trichobothrial area; (20) idem, posterior trichobothrial area; (21) idem, macrochaeta of posterior margin; (22) mesonotum, right half; (23) idem, anterior trichobothrial area; (24) idem, posterior trichobothrial area; (25) metanotum, left half; (26) idem, anterior trichobothrial area; (27) idem, posterior trichobothrial area. Scale bar = 0.1 mm.

Figures 28–35.Qantelsella louisae n.sp. holotype ♂ (28) prothoracic presternum, sternum and PI; (29) idem, enlargement of left comb of sternum; (30) comb of mesothoracic sternum; (31) other comb of mesothoracic sternum; (32) metathoracic sternum and PIII; (33) idem, right sternal comb; (34) idem, left sternal comb; (35) PII. Scale bar = 0.1 mm.

Figures 36–46. Qantelsella louisae n.sp. holotype ♂ (36) urotergite II; (37) left lateral comb of urotergite IV; (38) sublateral comb of urotergite V; (39) urotergite X; (40) urosternite VI; (41) left comb of urosternite VII; (42) urosternite VIII; (43) coxites IX with penis and stylets; (44) base of cerci (on left) and median filament (on right); (45) cerci, most apical surviving articles;(46) median filament, most apical surviving articles. Scale bar = 0.1 mm.