Introduction

The cosmopolitan genus Leptus is the biggest genus in the family Erythraeidae with about 231 species described based on larval or larval and post-larval forms (Haitlinger and Šundić 2020; Hakimitabar et al. 2020, 2021; Haitlinger et al. 2020a, b; Saboori et al. 2020, 2024; Xu et al. 2022a; Kapankaya et al. 2023; Khoobdel and Pakarpour Rayeni 2023). Kapankaya et al. (2023) wrote that 13 species have been described after Saboori et al. (2020) but they included only 11 species. The names of two species described by Xu et al. (2022b) are not available because the descriptions were issued in electronic form only and the paper is not correctly registered in Zoobank (see ICZN 2012).

Australia has a rich fauna of Leptus, including the species described by Southcott (1991, 1993, 1999) and catalogued by Mąkol and Wohltmann (2012), but no new species have been described since 1999. The Australian National Insect Collection includes a large number of specimens of Leptus that were examined by H.G. Womersley and R.V. Southcott, but which have not been formally described. Womersley applied the name Leptus (L.) brevitarsus to one of those undescribed species. After Womersley's passing, Southcott added some handwritten notes to the slide labels (main characters of the species) but did not describe this species either. Our purpose in this paper is to formalise the description of that species and present an updated key to torresianus species subgroup.

Materials and methods

The description is mainly based on four specimens examined by the first author, with additional data from 50 specimens examined by the second author. Figures were drawn and measurements were calculated using an AxioImager A2 (Carl Zeiss, Germany) compound microscope with phase contrast and DIC illumination. The photomicrograph was taken with an AxioCam 506 color (Carl Zeiss, Germany) digital camera. The digital figures were prepared using Adobe Illustrator version 2022 based on the original pencil line drawings. Measurements are given in micrometres (µm). Terminology and abbreviations follow Robaux (1974), Southcott (1992) and Saboori et al. (2009) except for Anterior Sensillary setae (ASens) and Posterior Sensillary setae (PSens).

Leptus (L.) brevitarsus sp. n. (Figs. 1, 2, 3) 

https://zoobank.org/urn:lsid:zoobank.org:act:7624FC4F-D46D-4A6C-8390-F31400F8A2B6

Diagnosis. Larva. With characters of the torresianus species subgroup, Ti I 88–100, Ti III 112–126, AW/AL 1.72– 2.53.

Fig. 1
figure 1

Leptus brevitarsus sp. n. (holotype larva). a Dorsal view of idiosoma; b ventral view of idiosoma; c gnathosoma

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Fig. 2
figure 2

Leptus brevitarsus sp. n. (larva). Scutum and idiosomal setae in one paratype (ARS-20230922-1d)

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Fig. 3
figure 3

Leptus brevitarsus sp. n. (holotype larva). a Tr–Ge I; b Ti–Ta I; c Tr–Ge II; d Ti –Ta II; e Tr–Ge III; f Ti–Ta III

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Description

Larva (n = 4). Gnathosoma cone-shaped, 147–163 long (chelicerae are broken from the distal end of the first segment) with galealae (cs) 14–17 in length (only can be seen in some paratypes; anterior part of gnathosoma broken in most specimens) and barbed, and with one pair of posterior hypostomalae (bs), barbed and 23–33 in length, and one pair of anterior hypostomalae (as) very minute. Palp trochanter without seta, palpal femur and genu each with one barbed seta, palpal tibia with one nude and two barbed setae, palpal tarsus with eight setae including a solenidion and an eupathidium. Subcapitulum, and all palpal segments punctate. Cheliceral bases with punctations and striations; striations thicker in distal half (Fig. 1c). Supracoxal seta of palp (eP), minute, 3–4 in length, peg-like. fPp = 0-B-B-BNB-2B4Nωζ (Fig. 1c).

Idiosoma oval with ~ 83–96 barbed short dorsal setae. Scutum sparsely punctate except anterolateral angles which are smooth (in holotype more parts are smooth as shown in Fig. 1a), wider than long with concave anterior border, almost straight anterolateral borders, and slightly concave posterolateral borders (Figs. 1a, 2); AL longer than PL, both with many barbs. Anterior pair of sensilla (ASens) shorter than posterior one (PSens), both barbed in distal half (Fig. 1a), ASens bases placed anterior to AL bases. One eye on each side of scutum, 14–17 in diameter, both circular.

Ventral surface of idiosoma with barbed sternalae; two barbed sternalae between each coxae I and II (1a and 2a, respectively); four barbed intercoxalae between coxae II and III and 26–34 barbed setae behind coxae III (Fig. 1b). Coxal fields punctate. NDV = 119–134.

Leg setal formula: Leg I (Fig. 3a, b): Ta- 1ω, 2ζ, 1ε, 27–28n; Ti- 2φ, 1κ, 14n; Ge- 2σ, 1κ, 8n; TFe- 5n (in one paratype 4n only on one side); BFe- 2n; Tr- 1n. Leg II (Fig. 3c, d): Ta- 1ω, 2ζ, 26n; Ti- 2φ, 15n; Ge- 1κ, 8n; TFe- 5n; BFe- 2n; Tr- 1n. Leg III (Fig. 3e, f): Ta- 1ζ, 26n; Ti- 1φ, 15n; Ge- 8n; TFe- 5n; BFe- 1n; Tr- 1n. Microseta on Ti I placed slightly proximal to distal solenidion. It is not common in Leptus species. Solenidion on Ta II placed in a big cavity and famulus was not visible.

Measurements are given in Table 1.

Table 1 Metric data of Leptus brevitarsus sp. n. (larva)
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Type material

Holotype larva, 4 miles NNE of Holt Rock, Western Australia, 32°38' S × 119°26' E, 3 November 1947, on a male grasshopper Austroicetes cruciata, collector not known (ANIC 52–003969). Paratypes: 1 larva, same data as holotype (ARS-20230922-1b); 2 larvae, 4 miles south of Lake Grace, Western Australia, 33°10' S × 118°28' E, 4 November 1947, on female Austroicetes cruciata, collector not known (ARS-20230922-1c, ARS-20230922-1d); 10 larvae, 36 miles east of Ongerup, Western Australia, 33°58' S × 119°00' E, 9 November 1947, on A. cruciata female (ANIC 52–003970 – ANIC 52–003979); 1 larva, 2 miles SSW of Ravensthorpe, Western Australia, 33°36' S × 120°02' E, 10 November 1947, on A. cruciata male (ANIC 52–003980); 3 larvae, 9 miles east of Yellowdine, Western Australia, 31°10' S × 119°50', 2 November 1947, on A. cruciata female (ANIC 52–003981); 2 larvae, 4 miles NNE of Holt Rock, Western Australia, 32°39' S × 119°28' E, 3 November 1947, on A. cruciata female (ANIC 52–003982, ANIC 52–003983); 3 larvae, 4 miles south of Lake Grace, Western Australia, 33°09' S × 118°29' E, 4 November 1947, on A. cruciata female (ANIC 52–003984, ANIC 52–003985, ANIC 52–003986); 7 larvae, 4 miles south of Lake Grace, Western Australia, 33°09' S × 118°29' E, 4 November 1947, on Austroicetes arida female (ANIC 52–003987 – ANIC 52–003993); 2 larvae, 6 miles west of Newdegate, Western Australia, 33°06' S × 118°54' E, 4 November 1947, on A. arida female (ANIC 52–003994, ANIC 52–003995); 2 larvae, 4 miles SE of Pingrup, Western Australia, 33°34' S × 118°32' E, 4 November 1947, on A. arida female (ANIC 52–003996, ANIC 52–003997); 18 larvae, 2 miles SSW of Ravensthorpe, Western Australia, 33°36' S × 120°02' E, 4 November 1947, on Austroicetes vulgaris corallipes male (ANIC 52–003998 – ANIC 53–004015); 1 larva, 2 miles SSW of Ravensthorpe, Western Australia, 33°36' S × 120°02' E, 10 November 1947, on A. vulgaris corallipes male (ANIC 53–004016); 2 larvae, 7 miles SE of Deakin, Western Australia, 30°49' S × 129°00' E, 24 October 1947, on Chortoicetes terminifera (ANIC 53–004017, ANIC 53–004018); 1 larva, 1 mile north of Wirrappa, South Australia, 31°24' S × 136°59' E, 14 October 1947, on C. terminifera (ANIC 53–004019); 1 larva, 2 miles WNW of Kingoonya, South Australia, 30°54' S × 135°15' E, 16 October 1947, on C. terminifera (ANIC 53–004020); 2 larvae, Forster to Cape Hawke, New South Wales, 32°12' S × 152°33' E, 15 December 1947, on Praxibulus laminatus female (ANIC 53–004021, ANIC 53–004022); 3 larvae, Forster, New South Wales, 32°12' S × 152°31' E, 4 December 1947, on P. laminatus male (ANIC 53–004023, ANIC 53–004025); 1 larva, Goologong to Forbes, New South Wales, 33°29' S × 148°17' E, 27 November 1947, on C. terminifera female (ANIC 53–004026). The holotype and 57 paratypes are deposited in the Australian National Insect Collection, CSIRO, Canberra ACT, Australia (ANIC). Three paratypes are deposited in the Acarological Collection, Jalal Afshar Zoological Museum (JAZM), Department of Plant Protection, Faculty of Agriculture, University of Tehran, Karaj, Iran.

Etymology

The name brevitarsus (Latin brevi, short) refers to the short tarsi of the species. It was named by H. Womersley.

Remarks

The new species belongs to phalangii species group and torresianus species subgroup in having one seta on each palpal femur and genu, four setae between coxae II-III, BFe III and TFe I without solenidion and Ge I with two solenidia (see Saboori et al. 2020). There are three species in this subgroup i.e. L. (L.) torresianus Southcott, 1988, L. (L.) francesi Southcott, 1991, L. (L.) multisolenidiae Mayoral & Barranco, 2011. Two of them were collected from Australia and only L. (L.) multisolenidiae was collected from French Guiana (South America).

The new species differs from all species of the subgroup in the placement of microseta on Ti I which is placed slightly prior to distal solenidia. In other species of the subgroup, it placed distinctly after distal solenidia. Also, it differs from L. (L.) multisolenidialae in the number of solenidia on Ge III (0 vs. 7–9), on Ge II (0 vs. 2), cheliceral bases (striate and punctate vs. only punctate), IP (1258–1340 vs. 2813–3097) and measurements of all leg segments; from L. (L.) francesi in the number of solenidia on Ti III (1 vs. 2), on Ti II (2 vs. 3), cheliceral bases (striate and punctate vs. only punctate), Ge I (71–80 vs. 126–143), Ti I (88–100 vs. 166–195), Ta I (97–109 vs. 152–159), Ge II (54–60 vs. 107–124), Ti II (64–70 vs. 149–184), Ta II (71–86 vs. 129–136), Ge III (61–66 vs. 116–147), Ti III (112–126 vs. 199–246), Ta III (92–98 vs. 141–154) and from L. (L.) torresianus in the fD (~ 83–96 vs. 50), cheliceral bases (striate and punctate vs. smooth), Ge I (71–80 vs. 155–160), Ti I (88–100 vs. 226–230), Ta I (97–109 vs. 162–165), Ge II (54–60 vs. 122–140), Ti II (64–70 vs. 195–199), Ta II (71–86 vs. 138–140), Ge III (61–66 vs. 139–155), Ti III (112–126 vs. 267–288), Ta III (92–98 vs. 156–160).

Key to species of torresianus species subgroup (modified after Saboori et al. 2020)

  • 1. Ge II with 2 solenidia, Ge III with 7–9 solenidia …………………………………………………………………………………..……….

  • L. (L.) multisolenidiae, French Guiana

  • – Ge II & III without solenidion ……………………........………………………………………………………………………...………… 2

  • 2. Ti II with 3 solenidia, Ti III with 2 solenidia  ....................................................................................................... (L.) francesi, Australia

  • – Ti II with 2 solenidia, Ti III with 1 solenidion ……................…………………………………………………………………………..…3

  • 3. Ti I 226–230, Ti III 267–288 ……………………………................……………………………………….... L. (L.) torresianus, Australia

  • – Ti I 88–100, Ti III 112–126 .................................................................................................................... (L.) brevitarsus sp. n., Australia

Discussion

The specimens examined here show that Leptus brevitarsus occurs in most areas of Australia. The species in the Leptus torresianus subgroup occur on a wide variety of hosts – L. torresianus was described from two species of cicadas (Hemiptera: Cicadidae), L. francesi from two species of flies (Diptera: Culicidae and Tabanidae), and L. multisolenidiae from a grasshopper (Orthoptera: Acrididae). We now add L. brevitarsus from several species of grasshoppers. Observations like these make it clear that the classification of species in the genus Leptus does not follow the classification of their hosts.