Visma stilivarians (Silvestri) Smith & Mitchell & Molero-Baltanás, 2021

Smith, Graeme B., Mitchell, Andrew & Molero-Baltanás, Rafael, 2021, Molecular and morphological studies identify a new genus within the Heterolepismatinae (Zygentoma: Lepismatidae), Zootaxa 5030 (1), pp. 1-118 : 100-107

Visma stilivarians (Silvestri) new combination

Table 12; Figs. 366–399

Heterolepisma stilivarians Silvestri, 1908: 47

Silvestri’s original illustrations of this species suggested that it should also be placed in the new genus Visma as it has the typical trapezoidal thoracic sterna and three, four or five pairs of styli. The shape of the ultimate article of the labial palp and the arrangement of its papillae and the shape of the parameres suggest that it may be most closely related to Visma xanthorrhoea n. sp. described below. However, with the current improved understanding of the characters in the Heterolepismatinae , there was some doubt whether all the material Silvestri included in this species was justified, especially when he himself noted the great variability in the number of pairs of styli. He dissected very little of the material he described, in most cases just removing and mounting a palp and a couple of abdominal sclerites. It is unlikely that he would have been able to observe the types of scales, a character that has emerged as quite important. The types of this species were obtained from the Zoological Museums in Berlin and in Hamburg along with permission to dissect and mount some specimens.

The ♀ holotype (gbs006060) from Donnybrook was found to conform with Visma according to its current definition and is redescribed below. All other specimens in the type series, including Silvestri’s allotype are either juveniles and therefore difficult to place or clearly belong to a different species or even genus. The species is described below based on Silvestri’s holotype alone. All other material is removed from the type series (see comments after description of V. stilivarians ).

Type material. Holotype WA: Donnybrook, S33.58 E115.83 1905 Hamburg Museum Expedition 145, 28./ 29. vii.1905, ♀ ( HW 1.56 ) on two slides (Berlin Museum) (gbs006060). Urotergite VI and urosternite VI, one maxil- lary palp, one labial palp, one antenna, the metathoracic sternum, one PI, one PII and both PIII are missing from this specimen. As most of these were illustrated by Silvestri in his original description, it is presumed that they were removed by him and mounted onto a slide, whose whereabouts is currently unknown.

Diagnosis. This species can most readily be distinguished from the other species of Visma in the group with 3+3 combs on urotergite I, by the presence of five pairs of styli, versus four pairs in V. xanthorrhoea n. sp. and three pairs in V. powellheueri n. sp. It is also distinguished from the closely related V. xanthorrhoea n. sp. by the slightly protruding and convex shape of the posterior margin of urosternite VII (versus straight) and the greater number of macrochaetae on the inner margin of the coxae of PI (four versus 1–2) (see remarks).

Redescription. Medium sized Heterolepismatinae , appearance when live unknown. Pigment faded in holotype after 124 years in alcohol. H+B length up to 10.4 mm; thorax length 3.4 mm or 0.33 H+B; width up to 2.1 mm with mesonotum being slightly wider than the pronotum and much wider than the mesonotum; antennae incomplete, length>0.57 H+B but probably almost equal to H+B; terminal filaments long,>0.8 H+B.

Macrochaetae smooth, hyaline to brown, apically bifurcate with truncated tips to each bifurcation. Some macrochaetae on tibia carrot-shaped.

Major scales quite broad, hyaline, with numerous subparallel ribs that do not surpass the margin of the scale ( Figs. 366 ). These round scales found on top of head, all nota, all thoracic sterna, and coxae, present on all urotergites and urosternites. Modified scales difficult to discern on femora, tibia and sub-basal divisions of terminal filaments but a few seen on femora appear to be of narrow, apically tapered, triangular form; scales on clypeus all appear to be lost. Scales not seen on styli, trochanter and tarsi. Most scales lost from nota but those few still present with ribs quite close together, similar to the description and illustrations by Silvestri.

Head: Wider than long ( Fig. 367 ), without distinct bushes. Frons projected strongly forward over the clypeus; anterior margin glabrous in the medial region although there are a couple of large macrochaetae (one each side) on the clypeus that give the appearance of being on the anterior margin of the frons. Lateral rows of macrochaetae extend along each side of head but there is a small but distinct gap between these rows and the macrochaetae surrounding the eyes; peri-antennal groups small (all setae or trichobothria-like hairs lost), the peri-antennal groups only tenuously connected with the marginal macrochaetae. Clypeus with 1+1 rows of macrochaetae near the frons as well as two on each side in the mid-region, otherwise with scattered thin setae and lanceolate or narrow triangular scales. Labrum with several macrochaetae scattered across the proximal third. Scape and pedicel of antenna ( Fig. 368 ) each with a subapical ring of small macrochaetae and setae on their face, scape with at least some lanceolate scales and possibly also narrow triangular scales on anterior and outer face, there appears to be a few scales on the anterior face of the pedicel. Sutures between the annuli of the basal articles of the flagellum very difficult to discern; each annulus appearing to have one or perhaps two rings of setae, trichobothria and some cilia. Each interval split into two annuli by about the tenth interval, with a trichobothrium in the most distal annulus only. The intervals further subdivided by about the 14th interval into four. Most distal surviving intervals ( Fig. 369 ) (probably about half full length) divided into repeated intervals of about eight annuli, with some annuli having two rings of setae or cilia; rod-like basiconic sensilla not seen with any confidence.

Mandibles typical for Heterolepismatinae , not strongly curved ( Figs. 370, 371 ), with well-developed molar and incisor areas; a group of about sixteen strong and short or thin and longer, apically bifurcated setae distally adjacent to the pectinate molar area and a bush of about 80 macrochaetae externally. Maxilla ( Figs. 372–374 ) with four thick apically bifurcate macrochaetae externally proximal to the palp; lacinia not particularly short and wide, with three strong teeth, one set only slightly further back than the other two, followed by about seven lamellate processes and a row of ten setae; galea with one stronger seta proximally but otherwise with only short fine cilia or setulae; apical article of maxillary palp 4.5 times longer than wide and about the same length as the penultimate article (0.97), the ultimate article with three slender simple papillae of the thin type in the apical third, the arms of the most distal hard to observe because of material adhering to its apex, basiconic sensilla (type C) not seen (unless the obscured branched papilla is actually a basiconic sensillum); last two articles of palp without thicker setae, third article with stronger setae forming an incomplete subdistal ring as well as two conspicuously stronger and apically bifurcate setae subdistally, two basal articles with incomplete subapical rings of thicker setae. Labium ( Fig. 375 ) much wider than long, postmentum with macrochaetae setae in an irregular scattered line across the anterior third, prementum with transverse and oblique groups of stronger setae and with short cilia and setulae distally; apical article of labial palp longer than wide (L/ W 1.16), with five subequal papillae of the compact type arranged in two rows, no basiconic sensilla observed; covered with numerous fine short setae, those proximal and laterally longer than those distal; penultimate article with only slightly stronger setae medially.

Pronotum ( Fig. 376 ) with setal collar of short to medium length macrochaetae and some small setulae and cilia; entire lateral margins with medium to short setae and some cilia as well as several longer marginal and submarginal macrochaetae. The anterior trichobothrial area ( Fig. 377 ) located 0.46 the distance along the lateral margin, the trichobothrium not associated with a macrochaeta but with 1–2 setulae. The posterior trichobothrium ( Fig. 378 ) mediad of a submarginal macrochaeta with a couple of setulae posterior to this group. Posterior margin with 1+1 single insertion points each associated with two cilia and a setula ( Fig. 379 ). Mesonotum ( Fig. 380 ) with similar lateral chaetotaxy to pronotum; none of the submarginal macrochaetae arranged in combs of two macrochaetae; the anterior trichobothrial areas ( Fig. 381 ) located about 0.69 along the margin with a macrochaeta located mediad of the short trichobothrium as well as a few setulae; the posterior trichobothrial area located about 0.82 the distance along the margin, with a very strong macrochaeta between the trichobothrium and the margin as well as a cilium and a few setulae; 1+1 posterior comb insertion points as in pronotum. Metanotum ( Fig. 382 ) similar to mesonotum with the trichobothrial areas ( Fig. 383 ) 0.73 and 0.82 along the margin, no macrochaeta associated with the anterior trichobothrial area; lateral margins also without combs of two macrochaetae; 1+1 posterior comb insertion points as in pronotum.

Presternum with an irregular transverse band of macrochaetae as well as smaller setae and cilia ( Fig. 384 ). All thoracic sterna with hyaline scales. Prothoracic sternum trapezoidal, about as long as wide at base (L/ W 0.98), entire lateral margins with fine setae, postero-lateral corners with 1+1 combs of 1–2 macrochaetae and 1–2 somewhat stronger simple marginal setae distally; posterior margin between the combs glabrous. Mesosternum ( Figs. 385 ) trapezoidal, about as long as wide at base (L/ W 0.98) with fine setae along posterior two-thirds of each lateral margin, 1+1 postero-lateral combs each of two long thick marginal seta and two macrochaetae, posterior margin between combs slightly concave and glabrous. Metasternum in Silvestri’s illustration much wider than long (L/ W 0.76), distal two-thirds of lateral margins with fine setae, each postero-lateral corner with a comb of two submarginal macrochaetae and 1–2 strong marginal seta as well as some cilia, posterior margin between the combs concave and glabrous.

Legs ( Figs. 384, 385 ) long; tibia L/W ratio of legs PI 2.5, PII 3.6; tarsi L/W ratio PI 6.3, PII 9.8. Precoxa of PI only ( Fig. 384 ) with comb of three strong macrochaetae and two setae near the anterolateral corner. Coxae with many strong macrochaetae along the external margin, inner margin with four macrochaetae in the distal half as well as a group of about six setae distally over the articulation as well as some fine setae distally on the dorsal face. Trochanter with one macrochaeta and one strong seta as well as several other setae. Femur ventrally with some macrochaetae along the posterior margin; anterior margin with a strong pointed seta about ⅔ along the margin and another close to the cluster of three or four smaller setae close to the distal end. Ventral face of femur with long thin triangular scales (some possibly approaching lanceolate) in the anterior half and long thin setae in the posterior half. Tibia with two macrochaetae along the dorsal margin and two narrow and one thicker carrot-shaped macrochaetae on the ventral margin as well as some longer setae along the face adjacent to the posterior margin; apical spur distinctly hooked and bearing several small setae; face of tibia also with setae and long thin triangular scales. Tarsi of four articles, the basal tarsal article of PI only slightly less than the length of the remaining articles together; second and third articles of PI short with two long setae and several smaller setae; second article of tarsi PII at least with trichobothrium-like seta. Pretarsus with two long curved lateral claws and a much shorter straight medial claw. PII ( Fig. 385 ) and PIII similar to PI except tibia of PIII probably with trichobothrium-like seta even though not illustrated by Silvestri, the basal tarsal article of PII about equal in length to the last three articles together, and of PIII just a little shorter than the distal three combined in Silvestri’s illustration.

Urotergites I – VII with 3+3 combs as shown in Table 12, each lateral comb associated with 1–3 marginal setae, 2–5 cilia and 2–6 setulae, each sublateral comb associated with 2–4 cilia, 0–2 marginal setae and 0–3 setulae and each submedial comb with 1–2 cilia and 0–1 setulae ( Figs. 386–389 ); urotergite VIII with 2+2 combs, lacking the sublateral comb, each lateral comb associated with three cilia, 1–2 marginal setae and 0–2 setulae; urotergite IX without combs but with a cilium and two small marginal setae or setulae in each infralateral corner ( Fig. 390 ). Urotergite X ( Fig. 391 ) round (L/ W 0.35, range 0.30–0.34) with numerous macrochaetae, setae and cilia along the lateral and slightly away from the margins, posterior margin damaged in holotype but probably with a few small setae .

Urosternite I glabrous, urosternites II–IV with 1+1 lateral macrochaetae each associated with 1–2 cilia, 0–1 marginal seta and 0–1 setula, urosternites V – VII similar but each bearing a pair of styli, with 1+1 lateral single macrochaeta mediad to each stylus ( Figs. 392, 393 ), each macrochaeta associated with a cilium, a marginal seta and several fine setulae, the corner laterad of each stylus with a cilium and 12 setulae. Coxites VIII of ♀ ( Figs. 394 ) with rounded, almost semi-circular inner process, each coxite VIII bearing a single macrochaeta mediad of the base of the stylus and several small setae or setulae and sometimes a cilium, outer process with a cilium and a few setulae. Five pairs of styli present (on urosternites V – IX) but those on V – VIII all lost from specimen .

On coxite IX of ♀ ( Figs. 394, 395 ) the internal process acute apically, about four times longer than the external process (range 3.9–4.1) and 2.5 times longer than wide at its base (range 2.44–2.52), external process with about six robust setae near the apex, internal and external margins of inner process with many strong setae or macrochaetae, inner process without a macrochaeta mediad of the base of the stylus insertion. Ovipositor ( Fig. 394 ) long, about 2.1 times as long as HW surpassing the end of the inner process of coxite IX by about four times the length of the inner process, composed of about 42 divisions (range 41–43). Distal divisions of gonapophyses ( Figs. 396 ) with numerous short fine setae and setulae .

Cerci ( Figs. 397, 398 ) with basal divisions much shorter than wide, each bearing 1–2 rings of fine setae, cilia and trichobothria as well as scales laterally, fifth division with two rings of setae, scales, cilia and trichobothria; ninth division much longer than wide with four rings with larger macrochaetae restricted to the most distal ring. It is not possible to determine the nature of the scales from the slide material, all scales appear long and thin, some appear to have lanceolate tips while other are truncate apically like triangular scales. Subsequent divisions with the number of rings gradually increasing. The most distal surviving divisions with about eleven annuli with macrochaetae present on the sixth and the most distal, trichobothria seen on second, seventh and eighth annuli but these difficult to observe when broken off. Median dorsal appendage ( Figs. 397, 399 ) with basal two divisions partially covered by the small rounded, apically indented epiproct, the next three divisions also short with only a single ring of long setae, next four divisions increasingly longer with two rings, following divisions with three then four rings with possible lanceolate scales present in the penultimate rings. Most distal surviving divisions similar to those of cerci with ten annuli separated into two chains, trichobothria present on the basal annulus of the second chain (or the sixth annulus).

Male unknown.

Remarks. Based on the chaetotaxy of the nota and abdominal tergite I this species is close to both V. xanthorrhoea n.sp. and V. powellheueri from South Australia, differing most obviously in the number of styli. Unfortunately we only have very limited molecular data for V. xanthorrhoea and none for either of the other two species.

Most other material listed by Silvestri as H. stilivarians was examined and is here removed from the type series. As each sample usually consisted of just a single specimen from which good quality molecular data is unlikely to be obtained, no attempt is made here to formally describe these species, although some comments on various characters are included below. It is hoped that additional material can eventually be obtained from the named collection localities to permit a thorough description linked to molecular data. These specimens are:

1) Juvenile (HW 0.54) WA: Karrakatta (ZMH) in alcohol (gbs006050) probably does not belong to Visma . It only has one pair of styli and the thoracic sterna do not appear to be trapezoidal.

2) Female (HW 1.05) WA: Coolgardie (ZMH) two slides (gbs006051) has glabrous anterior margin to frons, macrochaetae on labrum, papillae of ultimate article of labial palp in cluster arrangement, papillae of ultimate article of maxillary palp of narrow branched form (one appears to lack branches), scales not observed on clypeus, triangular scales on femora, scales of nota almost all lost, the few seen on the mesonotum all appear to have closely spaced ribs, pronotum with anterior trichobothrial area 0.4 along margin, posterior combs single, meso- and metanota lacking combs of two macrochaetae, all sterna are parabolic, but fringed with fine setae, second tarsal article has trichobothrium, urotergite I with 2+2 combs, short round urotergite X (like other Visma ), three pairs of styli (double stylus on VII). This species also probably belongs in Visma but differs from the V. stilivarians holotype in the shape of the thoracic sterna and the number of combs on urotergite I, as well as the number of styli.

3) Juvenile female (HW 0.58) WA: Coolgardie (ZMH) in alcohol (gbs006052) with styli on coxites IX only, the thoracic sternites are trapezoidal. It may or may not belong to Visma .

4) Female ( HW 1.15 ) WA: Wooroloo ( ZMH) on two slides (gbs006053) has macrochaetae along the front of the frons and macrochaetae on the labrum, a trichobothrium on the second tarsal article, the papillae of the labial palp are arranged in a tight cluster arrangement, the meso and metanota lack lateral combs of two macrochaetae and the posterior combs each have just a single macrochaeta, all thoracic sterna are parabolic rather than trapezoidal, although the posterior edge is a little truncate on the meso and meta sterna, no scales or obvious insertions were observed on the clypeus, scales on femora poorly preserved, possibly triangular or lanceolate, the remaining scales of the pronotum have widely spaced ribs, urotergite I has only 2+2 combs, urotergite X is shortish (like Visma rather than very short as in Maritisma), styli occur in four pairs, urosternite I is glabrous, 1+1 single macrochaetae on urosternites II– VII and coxites VIII of ♀. The species seems to belong to a different as yet undefined genus .

5) Juvenile (HW0.85) WA: Lunenberg (ZMH) in alcohol (gbs006054), not listed in Silvestri’s 1908 publication but labelled by Silvestri as a juvenile H. stilivarians . It has only one pair of styli and the thoracic sterna are parabolic in shape. It may or may not belong to Visma .

6) Subadult female (HW1.05) WA: Harvey (ZMH) in alcohol (gbs006055), not listed in Silvestri’s 1908 publication. This specimen has four pairs of styli and parabolic thoracic sterna. It was not dissected or further examined.

7) Female (HW 1.05) WA: Boorabbin (ZMH) on two slides (gbs006056), frons with glabrous anterior margin, macrochaetae on labrum, ultimate article of labial palp about as long as wide, its papillae in a cluster arrangement, papillae of ultimate article of maxillary palp of narrow branched form, clypeus appears to be without scales, femora appear to have long triangular scales, scales of nota all lost, pronotum with anterior trichobothrial area about 0.4 along margin, not associated with a macrochaeta, posterior combs single, meso and meta nota lacking combs of two macrochaetae, the anterior trichobothrial area of the mesonotum associated with a mediad macrochaeta, that of the metanotum without associated macrochaeta, all sterna distinctly parabolic, but fringed with fine setae, second tarsal article (at least on PI) has trichobothrium, urotergites I–VII with 3+3 combs, urotergite X is a little longer than usual for Visma spp. , three pairs of styli. This species also does not sit comfortably within Visma as currently defined and is clearly not the same species as the V. stilivarians holotype.

8) Juvenile female (HW 0.85) WA: Boyanup (ZMB) in alcohol (gbs006057), a juvenile with long and parabolic meso- and metasterna, the labrum with macrochaetae and only a single pair of styli. It may or may not belong in Visma as currently defined.

9) Female (HW 0.95) WA: East Fremantle (ZMB) on two slides (gbs006058), ovipositor broken off, frons with macrochaetae along the anterior margin, labrum with macrochaetae, clypeus probably without scales, the ultimate article of the maxillary palp bears thin papillae of the type typical for Visma spp. , the ultimate article of the labial palp is longer than wide and its papillae appear to be arranged in a cluster arrangement, the meso and metanota lack lateral combs of two macrochaetae and the posterior combs each have just a single macrochaeta, most scales of nota lost but scales with widely spaced ribs well represented; prothoracic sternum trapezoidal but with a slightly protruding posterior margin and so approaching parabolic, with a fringe of fine setae along ⅔ of the margin; the mesosternum is also trapezoidal but approaching parabolic, the metasternum is parabolic, no scales or obvious insertions were observed on the clypeus, scales on femora are triangular, a trichobothrium present on the second tarsal article (at least of PIII), urotergite I has only 2+2 combs, urotergite X is shortish (like Visma rather than very short as in Maritisma), styli occur in four pairs, urosternite I is glabrous, 1+1 single macrochaetae on urosternites II–VII and coxites VIII of ♀, the latter with the inner processes of which are rounded truncate rather than semi-circular as in V. stilivarians . The species, along with gbs006053 from Wooroloo, both of which have macrochaetae along the anterior margin of the frons, seems to belong to a different as yet undefined genus or subgenus.

10) Juvenile (HW 0.55) WA: Northhampton (ZMB) in alcohol (gbs006059), very small specimen, prothoracic sternum cordiform, ultimate article of labial palp obviously longer than wide, styli on IX only and appears to have setae on the anterior margin of the frons. It therefore is unlikely to belong to Visma .

11) Male (HW 1.13) WA: Yalgoo (ZMB) on two slides (gbs006061), Silvestri’s allotype, genital segments not present, presumably removed by Silvestri and mounted on slide, the whereabouts of which is unknown. Frons with glabrous anterior margin, clypeus with at least one narrow triangular scale with a rounded apex, labrum with macrochaetae; papillae of the labial palps appear to be arranged in a cluster, a trichobothrium on the second tarsal article, probably triangular scales on femora, scales on nota mostly lost but scales on pronotum include a good proportion of scales with widely spaced ribs, posterior combs of nota of single insertion points, meso and meta nota lacking combs of two macrochaetae, all thoracic sterna parabolic, urotergite I with 3+3 combs and four pair of styli. It thus also would appear to belong in Visma , in the group of species with 3+3 combs on urotergite I and lacking combs of two macrochaetae on the meso and meta nota (i.e. V. stilivarians , V. powellheueri n. sp. and V. xanthorrhoea n. sp.) but cannot be included with V. stilivarians due to the shape of the thoracic sterna, the widely spaced ribs on the scales and the reduced number of styli (only four pair).

Figures

FIGURES 366–375. Visma stilivarians (Silvestri) holotype ♀ 366. Round scale of mesonotum. 367. Head, clypeus damaged. 368. Antenna, scape, pedicel and basal intervals of flagellum. 369. Idem, most distal surviving interval. 370. Mandible. 371. Idem, incisor and molar regions. 372. Maxilla, smaller setae omitted from palp. 373. Idem, detail of lacinia. 374. Idem, ultimate article of palp three papillae (p). 375. Labium, with left palp missing. Scales: 0.1 mm.

FIGURES 376–385. Visma stilivarians (Silvestri) holotype ♀ 376. Pronotum, anterior and left margins. 377. Idem, anterior trichobothrial area. 378. Idem, posterior trichobothrial area. 379. Idem, right comb of posterior margin. 378. Mesonotum, left margin. 381. Idem, detail of trichobothrial areas. 382. Metanotum, left margin. 383. Idem, detail of trichobothrial areas 384. Presternum, prothoracic sternum and PI. 385. Mesothoracic sternum and PII. Scales: 0.1 mm.

FIGURES 386–396. Visma stilivarians (Silvestri) holotype ♀ 386. Urotergite III. 387. Urotergite VII, left lateral comb. 388. Idem, left sublateral comb. 389. Idem, left submedial comb. 390. Urotergite IX, left infralateral comb. 391. Urotergite X. 392. Urosternite VII. 393. Urosternite V, detail of right stylus insertion. 394. Coxites VIII and IX and ovipositor. 395. Coxite IX with stylus. 396. Apex of ovipositor valves. Scales: 0.1 mm.

FIGURES 397–399. Visma stilivarians (Silvestri) holotype ♀ 397. Base of cercus and median dorsal appendage. 398. Apical division of median dorsal appendage. 399. Apical division of cercus. Scales: 0.1 mm.