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Research Article
Extension of the phasmid genus Presbistus to Cambodia with a new species and notes on genitalia and captive breeding (Phasmida, Aschiphasmatidae, Aschiphasmatinae)
expand article infoJoachim Bresseel, Jérôme Constant
‡ Royal Belgian Institute of Natural Sciences, Brussels, Belgium
Open Access

Abstract

A new species of Presbistus Kirby, 1896, Presbistus vitivorus sp. nov., is described from Cambodia based on both sexes, nymphs, and eggs. Male genitalia and vomer are described and figured. Illustrations of adults, nymphs, specimens in situ, host plants, a distribution map and records on biology and breeding in captivity are provided. The host plants of the species belong to the family Vitaceae. The genus Presbistus and the family Aschiphasmatidae are recorded from Cambodia for the first time. The species diversity and the distribution of the genus are discussed, and it is shown that the genus is restricted to Sundaland. A nomenclature for the morphology of the dissected vomer is proposed and tries to homologize the previously used terms.

Keywords

Aedeagus, Aschiphasmatini, Phasmatodea, stick insect, Vitaceae, vomer

Introduction

The genus Presbistus Kirby, 1896 belongs to the Aschiphasmatini in the subfamily Aschiphasmatinae and currently contains nine species. Phylogenetic studies have shown Aschiphasmatinae to be monophyletic and the sister group to all remaining Euphasmatodea (Simon et al. 2015).

Presbistus is currently recorded from India, Sri Lanka, Peninsular Malaysia, Sumatra, Java, and Borneo (Brock et al. 2022). Within the Aschiphasmatinae, the genus is characterized by triangular or spine-like tegmina, uniform translucent brown anal region of hind wings, and cylindrical or conical cerci in both sexes. The male has a well-developed vomer and has the end of the abdomen distinctively swollen and club-shaped. The eggs are slightly longer than high and lack setae (Bragg 2001, Seow-Choen 2016).

The vomer, a sclerotized derivative of sternum X, was first introduced by Pantel (1890) as “vomer sous-anal”. The vomer is used during mating and clasps the posterior margin of sternum VII of the female, which has evolved into a praeopercular organ (Bradler 2003). Pantel (1915) discussed the structure and variability of the vomer in different subgroups of Phasmatodea and detected a vomer in three genera of “Ascepasmini” (= Aschiphasmatini) including Presbistus. Bradler (1999, 2009) argued that the vomer was already present in the phasmatodean ground plan and that it represents a plesiomorphic character for all Euphasmatodea. Most authors have only described the external part of the vomer, and a standardized nomenclature for the different parts of this organ is still needed.

During the study of stick insect specimens collected in the framework of the Global Taxonomy Initiative project “A step further in the entomodiversity of Cambodia,” a species belonging to the genus Presbistus could not be attributed to any known species.

The phasmid fauna of Cambodia remains poorly studied (Bresseel and Constant 2018b), and the present paper describes the new species as Presbistus vitivorus sp. nov., provides useful characters for differentiation, and gives information on its biology and distribution. A nomenclature for the morphological characterization of the vomer in stick insects is proposed.

Materials and methods

Due to their nocturnal behavior (as in most Phasmida), the specimens of P. vitivorus sp. nov. were collected at night. A lightweight, water-proof Petzl MYO RXP head torch was used during collecting. The females were kept alive in a mesh pop-up cage (exo terra explorarium) for producing eggs. The wild caught specimens were euthanized by injection with ethanol. The specimens were then stored in airtight plastic “zip” bags containing wood chips commonly used in rodent cages and sprinkled with etylacetate (EtOAc) to prevent rotting, mould, and to keep the specimens flexible. The bags were frozen on arrival, and the specimens were mounted at a later date.

A number of pictures of each specimen were taken using a Canon 700D camera (Canon Inc., Ota City, Tokyo, Japan) equipped with a Sigma 50 mm macro lens (Sigma Corporation, Kawasaki, Japan) for adults or with a Leica EZ4W stereomicroscope (Leica Microsystems Ltd., Wetzlar, Germany) with integrated camera for eggs and male genitalia. The images were stacked using CombineZ software (https://combinezp.software.informer.com) and optimized with Adobe Photoshop CS3. The distribution map was produced using SimpleMappr (Shorthouse 2010). Observations were done with a Leica EZ4W stereomicroscope, and measurements were taken with an electronic calliper. The dissection of the vomer and aedeagus was done on a fresh specimen using a needle blade. The vomer was extracted after cutting the membrane around the connective ring that separates the internal apodemes from the externally visible body; the aedeagus was extracted after spreading the poculum and cutting the inner membrane around the integument that separates the internal basal apodeme from the external remaining parts of the aedeagus. After extraction, the vomer and aedeagus were boiled for a few minutes in 10% KOH solution to remove the remaining soft parts then rinsed and examined in 70% ethanol. The vomer and aedeagus were preserved in glycerine in a polyethylene genitalia tube and stored under the label of the corresponding specimen.

The nomenclature of the morphological characters follows Bragg (2001) and that of the egg morphology follows Clark-Sellick (1997, 1998). The description of the coloration is based on live specimens.

Acronyms used for the collections.

RBINS Royal Belgian Institute of Natural Sciences, Brussels, Belgium.

RUPP Royal University of Phnom Penh, Cambodian Entomology Initiative, Phnom Penh, Cambodia.

VNMN Vietnam National Museum of Nature, Hanoi, Vietnam

Abbreviations.

HT holotype

PT paratype

Results

Taxonomy

Family Aschiphasmatidae Brunner von Wattenwyl, 1893

Subfamily Aschiphasmatinae Brunner von Wattenwyl, 1893

Tribe Aschiphasmatini Brunner von Wattenwyl, 1893

Presbistus Kirby, 1896

Presbistus Kirby, 1896: 475. – Kirby 1904: 475 [in Aschiphasminae]. — Redtenbacher 1906: 78 [redescribed]. — Ragge 1955: 377 [wing venation]. — Bradley and Galil 1977: 200 [in Aschiphasmatinae]. — Brock 1999: 147, 154, 184 [species from Peninsular Malaysia]. — Bragg 2001: 323, 642 [species from Borneo]. — Zompro, 2004: 318 [in superfamily Aschiphasmatoidea]. — Otte and Brock 2005: 280 [Catalogued]. — Seow-Choen 2016: 359 [species recorded and figured from Borneo]. — Seow-Choen 2017: 128 [species recorded and figured from Singapore]. — Seow-Choen 2018: 577 [species recorded and figured from Sumatra].

Type species.

Perlamorpha peleus Gray, 1835 by original designation.

The genus Presbistus can be distinguished from other members of the Aschiphasmatinae by the combination of the following set of characters (adapted from Bragg 2001):

Body and legs brown with some black markings.

Mesonotum unarmed.

Profemora incurving at base; all femora with distinct medioventral carina, armed with at least a few minute spines.

Tegmina triangular and spine-like; anal region of hind wing translucent brown.

Apex of male abdomen distinctly swollen.

Apex of female abdomen almost arrowhead shaped in dorsal view. Subgenital plate with anterior portion globose, posterior half medially keeled and tapering.

Cerci cylindrical.

Eggs longer than high, lacking setae.

Presbistus vitivorus sp. nov.

Figs 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12

Diagnosis and differentiation.

The new species is morphologically most similar and believed to be closely related to two Bornean species: Presbistus marshallae Bragg, 2008 and P. appendiculatus Bragg, 2001. All three species have a cleft anal segment in males, with the left anal lobe (lal) shorter than the right (ral), and the right anal lobe twisted. In P. vitivorus sp. nov., ral first curves down towards the front and later upwards, projecting between the right cercus and the posterior margin of tergum IX. Sternite VII of females of the new species is not rounded or bilobed and does not notably project over the base of the operculum. Instead, the posterior portion of tergum VII is slightly narrowing with the praeopercular organ present as a posterior depression with indistinct lateral carinae and concave posteriorly. The new species also has relatively shorter hind wings compared to most of the other species of the genus. There is only a single species with two subspecies that have shorter hind wings: Presbistus asymmetricus viridialatus Seow-Choen, 2020 and Presbistus asymmetricus asymmetricus Giglio-Tos, 1910.

Etymology.

The species name is formed from the plant genus name Vitis, belonging to the family of the grapevine Vitaceae and the suffix forming adjective -vorus (feminine -vora, neuter -vorum) meaning “eating” or “devouring”. It refers to the feeding preference of the species for plants of the family Vitaceae.

Type material.

Holotype: CAMBODIA • ♂; Pursat prov., Phnom Samkos; 12°13'02"N, 102°55'07"E; 15–18 October 2016; GTI project; Leg J. Constant & J. Bresseel; I.G.: 33.345; RBINS. Paratypes: CAMBODIA • 7♂, 22♀; same collection data as holotype; 4♂, 19♀: RBINS; 2♂, 2♀: RUPP; 1♂, 1♀: VNMN.

Additional material.

CAMBODIA • 10♀; Preah Vihear prov., Be Treed Adventures; 16–21 October 2017, 13°29'44"N, 104°42'36"E; GTI Project; Leg. J. Constant & X. Vermeersch; I.G.: 33.551; 8♀: RBINS; 2♀: RUPP • 3♀; Preah Vihear prov., Be Treed adventures; 16–21 October 2017, 13°29'44"N, 104°42'36"E; GTI Project; Leg. J. Constant & X. Vermeersch; I.G.: 33.551; Ex breeding Tim Bollens, 2018; RBINS • 21♀; Preah Vihear prov., Be Treed adventures; 16–21 October 2017; 13°29'44"N, 104°42'36"E; GTI Project; Leg. J. Constant & X. Vermeersch; I.G.: 33.551; Ex breeding Tim Bollens, 2019; RBINS • Six eggs; same data as holotype;RBINS; RUPP.

Remark.

Living females from Phnom Samkos have the alae slightly projecting over the posterior margin of tergum V, but not reaching half of tergum VI. In living females from Be Treed, the alae are longer and slightly but noticeably projected over half of tergum VI. Breeding efforts have proven that wing length is a stable feature throughout successive generations. Therefore, even if no other differences could be observed, the specimens from Be Treed are not listed as type material.

Description.

Male. (Figs 15) Body. Setae scattered over complete body, more concentrated in certain areas. Head, pro- and mesonotum brown with distinct black patches. Wings with blackish tegmina; costal area of alae brown with black markings and with basal portion of radius green, anal area infuscate. Femora brownish dorsally with black apex. Tibiae brownish, protibiae with black base and apex; mesotibiae with black apex and metatibiae with indistinct black marking apically.

Head . (Fig. 1C, E) Flattened dorsally, wider than long with a shallow longitudinal impression posteriorly. Eyes strongly protruding. Two minute impressions between the bases of antennae. Antennae reaching about half of abdomen; scapus subcylindrical, roughly as long as pedicellus. Pedicellus cylindrical. First flagellomere longer than pedicellus; flagellomere II shorter than half the length of previous one; following segments varying in length.

Fig. 1. 

Presbistus vitivorus sp. nov. holotype male (RBINS). A. Dorsal view; B. Ventral view; C. Head and thorax, dorsal view; D. Lateral view; E. Head and thorax, lateral view; C, E not to scale.

Thorax . (Fig. 1C, E) Pronotum longer than wide with posterior margin concave and with a median line in the prozona; prozona slightly higher than metazona from lateral view; lateral margins slightly concave from dorsal view, posterior margin more or less straight. Mesonotum about one third longer than pronotum and parallel-sided; anterior margin slightly concave with raised rim.

Wings . (Fig. 1A, B) Tegmina small, elongate, triangular, and apically acute; pointing straight upwards. Hind wings reaching roughly halfway tergum VI.

Legs . (Fig. 1A, B) Profemora incurved basally. Femora with carinae indistinct, outer ventral carinae with few minute spines. Tibiae with carinae indistinct.

Abdomen and terminalia . (Figs 1A, B, D, 25) Terga II–VII of uniform width and terga II–VI only slightly varying in length; tergum VII (t7) distinctly shorter; tergum VIII (t8) and IX (t9) widening towards the posterior; X narrower than IX. Anal segment (as) with indistinct mediolongitudinal carina, slightly widening towards the posterior; apex notched. Right anal lobe (ral) broad at base, distinctly elongated and strongly twisted and curved, projecting between cercus and posterior margin of tergum IX. Left anal lobe (lal) distinctly shorter than right one and curved. Cerci (ce) black and long, incurved and round in cross section with an apical tooth. Poculum bulgy and angular (110° angle), posterior part with fine mediolongitudinal carina, apex rounded.

Fig. 2. 

Presbistus vitivorus sp. nov. male terminalia. A. Posterior view; B. Dorsal view; C. Right lateral view; D. Ventral view; E. Right laterodorsal view; F. Left lateral view. Abbreviations: as, anal segment. ce, cercus. dp, dorsal process. po, poculum. t7, tergum VII. t8, tergum VIII. t9, tergum IX.

Fig. 3. 

Presbistus vitivorus sp. nov. male anal segment. A. Posterior view; B. Posterodorsal view; C. Right posterolateral view; D. Left lateral view; E. Right lateral view. Abbreviations: c, cercus. lal, left anal lobe. ral, right anal lobe.

Vomer (Fig. 4) well developed. Body (b) with narrow base, distinctly elongated, tapering and ending in an apical spine (as); ventral part of body distinctly longer than dorsal part. Left and right basal apodemes (lba, rba) narrow and elongated, almost as long as the vomer body. External body separated from internal apodemes by sclerotized connective ring (cr). Apodemes almost parallel, slightly directed towards each other.

Fig. 4. 

Presbistus vitivorus sp. nov. male vomer. A. Ventral view; B. Left lateral view; C. Dorsal view; D. Ventrolateral view; E. Right lateral view. Abbreviations: as, apical spine. b, body. cr, connective ring. lba, left basal apodeme. rba, right basal apodeme.

Aedeagus (Fig. 5) with spatulate, elongate, and curved basal apodeme (ba) prolongated anterodorsally by a strongly sclerotized plate (dorsal sclerite). Sclerotized plate with elongated club-shaped right basal process (rbp), with blunt subtriangular left basal process (lbp) and with elongated curved dorsal process (dp) bearing minute teeth on anterior surface (Fig. 5F). Caudal portion of aedeagus composed of a series of membranous lobes (ml).

Fig. 5. 

Presbistus vitivorus sp. nov. ♂ aedeagus. A. Dorsal view; B. Right lateral view; C. Left lateral view; D. Ventral view; E. Laterodorsal view; F. Detail of dorsal process. Abbreviations: ba, basal apodeme. dp, dorsal process. ml, membranous lobe. lbp, left basal process. rbp, right basal process.

Female. (Figs 6, 7)

Body . Setae scattered over complete body, more concentrated in certain areas. Female colored as male except for abdomen. In the female, tergum VII conspicuously paler than the rest of the abdomen.

Head . (Fig. 6C, E) About as long as wide, flattened dorsally. Eyes strongly protruding. Two minute impressions between the bases of the antennae. Antennae reaching about half of abdomen; scapus flattened at base, cylindrical at apex, slightly longer than pedicellus. Pedicellus cylindrical. First flagellomere longer than pedicellus; flagellomere II shorter than half the length of previous segment; following segments vary in length.

Fig. 6. 

Presbistus vitivorus sp. nov. paratype female (RBINS). A. Dorsal view; B. Ventral view; C. Head and thorax, dorsal view; D. Lateral view; E. Head and thorax, lateral view. C, E not to scale.

Thorax . (Fig. 6C, E) Pronotum longer than wide with anterior margin slightly concave and with a median line in the prozona; prozona slightly higher than metazona from lateral view; impression between pro- and metazona centrally flattened, almost circular, sublaterally with a minute hole; lateral margins slightly concave from dorsal view, posterior margin more or less straight. Mesonotum almost twice as long as pronotum and parallel-sided, with posterior margin slightly concave with a raised rim and anterior margin almost straight.

Wings . (Fig. 6A, B) Tegmina small, elongate, triangular, and apically acute; pointing straight upwards. Hind wings projecting over posterior margin of tergum V but not reaching posterior margin of tergum VI.

Legs . (Fig. 6A, B) As in male.

Abdomen . (Figs 6A, B, D, 7) Terga II–V of uniform width, terga VI–VIII slightly widening towards the posterior (this feature usually only visible in living specimens and especially in females with the abdomen swollen with eggs). Terga VII–X getting progressively shorter with VIII–X tectiform. Tergum VIII expanding laterally with lateral margin rounded. Anal segment slightly shorter than tergum IX; apex concave with minute epiproct visible in dorsal view. Cerci narrow, circular in cross section. Sternum VII with praeopercular organ present as a posterior depression with indistinct lateral carinae, indistinctly projecting over base of subgenital plate and concave posteriorly. Subgenital plate with anterior portion globose and with minute impression basally; posterior portion with distinct mediolongitudinal carina, narrowing towards the posterior with apex roundly pointed.

Fig. 7. 

Presbistus vitivorus sp. nov. female, terminalia. A. Dorsal view; B. Lateral view; C. Ventral view.

Nymph. (Fig. 8) Newly hatched nymphs have a pinkish body and head. Antennae longer than head and body combined, orange with evenly spaced black markings. Legs slightly setose and completely orange.

Fig. 8. 

Presbistus vitivorus sp. nov., newly hatched nymph. Photo credit T. Bollens.

Egg. (Fig. 9) Measurements [mm]: length 1.9, width 0.9, height 1.5. Capsule dark reddish brown, surface minutely punctuate without setae; lentil shaped and laterally compressed. Micropylar plate colored like capsule, long and narrow, longitudinally carinate laterally and medially, extending from the operculum across the polar end and back to the operculum. Micropylar cup distinct, displaced towards the polar area; operculum elongate oval, not punctuate, with a raised elongate oval ridge centrally.

Fig. 9. 

Presbistus vitivorus sp. nov. egg. A. Dorsal view; B. Lateral view; C. Anterolateral view; D. Ventral view; E. Opercular view; F. Polar view; G. Posterolateral view.

Table 1.

Measurements [mm] of Presbistus vitivorus sp. nov.

Length of HT PT ♂♂ PT ♀♀
Body 44.6 42.2–44.1 50.8–57.4
Head 2.6 2.4–2.6 3.1–3.5
Pronotum 3.3 3.1–3.4 3.9–4.4
Mesonotum 5.5 5.5–5.8 6.8–7.6
Tegmina 1.7 1.7–2.0 2.2–2.4
Alae 23.5 21.8–24.6 27.6–30.0
Metanotum 2.1 covered by wings 4.0*
Median segment 3.6 covered by wings 4.9*
Profemora 7.6 7.2–8.2 8.4–9.4
Mesofemora 5.9 5.1–6.2 6.1–6.9
Metafemora 10.4 9.4–10.8 10.9–12.9
Protibiae 6.7 6.3–7.3 6.7–7.9
Mesotibiae 5.9 5.2–6.2 5.9–6.5
Metatibiae 10.4 9.3–11.1 10.0–12.1

Biology.

Wild specimens were found in Phnom Samkos on Vitaceae (identification of the wild Vitaceae by A. Trias-Blasi, pers. com., VII.2019) species belonging to the genus Tetrastigma (Miq.) Planch. or Cayratia (Baker) Suess. and were fairly numerous on their host plants (Figs 10, 11A–D). Males and females were present in this population, with most males found in copula (Fig. 10E). In Be Treed, they were common on Vitaceae of the genus Ampelocissus Planch., but only females were found, thus this particular population seems to be parthenogenetic (Fig. 11E–G). From this latter parthenogenetic population, P. vitivorus sp. nov. was cultured by T. Bollens (Belgium) on various Vitaceae (Parthenocissus spp., Cissus alata Jacq., Vitis vinifera L.) of which the latter species was the preferred alternative food. The eggs are dropped to the ground, and the young nymphs are bright red in color after hatching but turn green after a few days. They hide mainly underneath leaves and are very fast and hectic when disturbed. Incubation of eggs was performed without a diapause and lasted 6 months, or with a 5–6 months diapause in the refrigerator and then lasted 4 months after the diapause. Females produce many eggs, with up to 10 eggs dropped per day by each female.

Fig. 10. 

Presbistus vitivorus sp. nov. in nature in Cambodia, Phnom Samkos, 16.X.2016. A. Male on Vitaceae sp., laterodorsal view; B. Ditto, terminalia, lateral view; C. Female on vitaceae sp., laterodorsal view; D. Ditto, dorsal view; E. Pair in copula, lateral view; F. General view of habitat; G. Damage on leaves of Vitaceae sp.

Fig. 11. 

Presbistus vitivorus sp. nov. in nature in Cambodia. A–E. Phnom Samkos, 17.X.2016. A. Female on Vitaceae sp., lateral view; B. Ditto, general view of habitat; C. Host plant, Vitaceae sp., leaves; D. Host plant, fruit; E. Host plant, Vitaceae sp., leaves and fruits; F, G. Be Treed, on Ampelocissus sp., 16.X.2017; F. Female, laterodorsal view; G. Female, dorsal view; H. Be Treed, female on Ampelocissus sp., 19.X.2017.

Distribution.

Cambodia: Pursat and Preah Vihear provinces (Fig. 12).

Fig. 12. 

Presbistus vitivorus sp. nov. distribution map.

Discussion

Male terminalia.—The morphology of the external terminalia in Aschiphasmatidae was recently studied (Valotto et al. 2016a, b), but the internal male genitalia have remained almost completely undocumented. Several studies provide basic information on phasmid genitalia (Chopard 1920, Walker 1922, Snodgrass 1937), but Helm et al. (2011) provided the first detailed study based on the Oriental species Oxyartes lamellatus Kirby, 1904 (Lonchodidae, Necrosciinae). Genitalia in Neotropical taxa were recently studied by Heleodoro and Rafael (2019), Chiquetto-Machado and Cancello (2021), and Ghirotto (2021), highlighting the importance of the phallic organ characters for phasmid systematics. At least the large sclerotized and specialized dorsal portion in Presibistus vitivorus sp. nov. seems to be homologous to the dorsal sclerite found in all species examined in the previously mentioned studies and coincides with the hypothesis by Helm et al. (2011) that the dorsal sclerite may be present in all or nearly all species of stick insects.

In Presbistus, the aedeagus is moderately sclerotized and shows considerable differences when compared to other studied taxa. The aedeagus provides several interesting characters for species differentiation and future phylogenetic considerations, but since our study represents the first documentation of a dissected aedeagus for the subfamily, no conclusions regarding these subjects can be drawn.

The characters of the male vomer are frequently used when describing or differentiating stick insect taxa (Bradler 2009, Bresseel and Constant 2018a, Cumming et al. 2021). The nomenclature proposed here for the dissected vomer can be used in nearly all species, and the structure of the vomer provides useful differential characters when studied from different angles. The suggested nomenclature (Fig. 4) tries to homologize with previously used terms. The vomer of a number of genera has been dissected, such as Timema Scudder, 1895 (Timematoidea), Cryptophyllium Cumming et al., 2021 (Phyllioidea), Dajaca Brunner von Wattenwyl, 1893 (Vallotto et al. 2016a), and Orthomeria Kirby, 1904 (Aschiphasmatoidea) (Bradler 1999, Vallotto et al. 2016a, b, Cumming et al. 2021), and these studies show the presence of two basal apodemes (Fig. 4: lba, rba) embedded in the body. The structure and direction of these apodemes can differ considerably between genera.

The body of the vomer (Fig. 4: b) refers to the external part of the vomer including the distal ending and is connected to the tegument by the connective ring (Fig. 4: cr). The body of the vomer shows considerable variation in shape but most often narrows towards the posterior. This organ can be functionally replaced or can be strongly reduced in genera with a modified tergum X or specialized cerci for clasping the female (Pantel 1915, Bradler 2003, 2009, Hennemann and Conle 2008).

The apical portion of the body of the vomer is often upcurved and armed with one to multiple spines. In many species the vomer ends in a single apical spine (Fig. 4, as), referred to as hook(s) or prong(s) by several authors (Bradler 1999, Bradler et al. 2014, Cumming et al. 2021). The apex can sometimes be more complex, bearing two (Neooxyartes Ho, 2018, Cryptophyllium) or more (Spinohirasea Zompro, 2002, Paramenexenus Redtenbacher, 1908) sometimes blunt, spines (Hennemann 2007, Bresseel and Constant 2018a, Bradler et al. 2014, Cumming et al. 2021). The body of the vomer can be symmetrical (Neooxyartes) to asymmetrical (Cryptophyllium) depending on the size and direction of the spine(s) (Bresseel and Constant 2018a, Cumming et al. 2021).

Species diversity and distribution.—With the description of this new taxon there are now ten known Presbistus Kirby, 1896 species. The family Aschiphasmatidae is for the first time recorded from Cambodia, with Presbistus vitivorus sp. nov being only the fifth species of stick insect described from the country (Brock et al. 2022).

Presbistus peleus (Gray, 1835), the type species, is the most widespread species in the genus and is recorded from India, Peninsular Malaysia, Singapore, Sumatra, and Borneo (Brock et al. 2022). The holotype originates from “Ora Malabariensi” (Gray 1835), considered the Malabar coast (India) by subsequent authors (Brock 1999, Bragg 2001). However, both authors expressed doubts about the accuracy of the original locality, as all subsequent records originate from Sundaland and the genus has never been confirmed in India. Other species described by Gray (1835) bearing the same collecting data and all “ex collection D. Children” have since been recorded from Peninsular Malaysia (Malacca) (Brock 1999, Bragg 2001). Therefore, the Indian record of P. peleus is regarded as erroneous. Furthermore, from photographs of the holotype female available from Brock et al. 2022, it appears that P. crudelis (Westwood, 1859) from Sri Lanka is not congeneric with the type species of Presbistus, P. peleus (Gray, 1835), and belongs in a separate, yet undescribed genus that differs from Presbistus by the almost straight profemora, the comparatively shorter mesonotum, and the spoon-shaped subgenital plate. Hence, the genus Presbistus is removed from the list of stick insects from India and Sri Lanka.

With P. vitivorus sp. nov extending the distribution of Presbistus to Cambodia, the genus is shown to be distributed over most of Sundaland, comprising Indochina, the Malay Peninsula, Sumatra, Java, and Borneo.

Acknowledgments

We thank Sophany Phauk (RUPP) and his students as well as Dr. Hong Thai Pham (Vietnam National Museum of Nature, Hanoi, Vietnam) and Xavier Vermeersch (RBINS collaborator) for their help, enthusiasm, and friendship during the collecting trips. Myriam Bourguignon and the staff and students of KTA Horteco (Vilvoorde, Belgium) are thanked for cultivating the plants needed for rearing the species in captivity. We also thank Tim Bollens (Herselt, Belgium) for his help in captive rearing of the species and providing additional study material and Cédric Cauquil (Soual, France) for additional information on incubation. Dr. Anna Trias-Blasi (Royal Botanic Gardens, Kew, UK) is thanked for her help in identifying the food plants from our photographs. Thank you to the authorities of Phnom Samkos Wildlife Sanctuary for their support of this study, to Sharyn and Benjamin J. Davis, the managers of Be Treed and the Cambodian Ministry of Environment for allowing and facilitating our research at BeTreed Adventures. Dr. Patrick Grootaert, Dr. Yves Samyn, and Dr. Marie-Lucie Susini (RBINS) are thanked for their permanent support of the project in Cambodia, Mado Berthet (RBINS) for improving the illustrations, and Gerard Chartier (Tatai, Cambodia) for his help in the field and hospitality. This paper is a result of the project “A step further in the entomodiversity of Cambodia” (2016–2017) supported through grants issued by the capacity building program of the Belgian Global Taxonomy Initiative National Focal Point that runs under the CEBioS program with financial support from the Belgian Directorate-General for Development Cooperation.

References

  • Bradley JC, Galil BS (1977) The taxonomic arrangement of the Phasmatodea with keys to the subfamilies and tribes. Proceedings of the Entomological Society of Washington 79: 176–208.
  • Bradler S (1999) The vomer of Timema Scudder, 1895 (Insecta: Phasmatodea) and its significance for phasmatodean phylogeny. Courier Forschungsinstitut Senckenberg 215: 43–47.
  • Bradler S (2009) Die Phylogenie der Stab- und Gespenstschrecken (Insecta: Phasmatodea). Phylogeny of the stick and leaf insects (Insecta: Phasmatodea). Species, Phylogeny and Evolution 2: 3–139. https://doi.org/10.17875/gup2009-710
  • Bradler S (2003) Phasmatodea, Gespenstschrecken. In: Dathe (Ed.) Lehrbuch der speziellen Zoologie. I. Wirbellose Tiere. 5. Insecta. Spektrum, 251–260.
  • Bradler S, Robertson JA, Whiting MF (2014) A molecular phylogeny of Phasmatodea with emphasis on Necrosciinae, the most species-rich subfamily of stick insects. Systematic Entomology 39: 205–222. https://doi.org/10.1111/syen.12055
  • Bragg PE (2001) Phasmids of Borneo. Natural History Publications (Borneo), Kota Kinabalu, 772 pp.
  • Bresseel J, Constant J (2018a) Two new stick insect genera from Vietnam, Nuichua gen. nov. and Pterohirasea gen. nov. with two new species (Phasmida: Diapheromeridae: Necrosciinae). Belgian Journal of Entomology 70: 1–29.
  • Bresseel J, Constant J (2018b) The stick insect genus Medauroidea Zompro, 2000: Taxonomic note and extension to Laos and Cambodia with one new species, M. romantica sp. nov. (Phasmida: Phasmatidae: Clitumninae). Belgian Journal of Entomology 73: 1–19.
  • Brock PD (1999) Stick and Leaf Insects of Peninsular Malaysia and Singapore. Malaysian Nature Society, Kuala Lumpur, 223 pp.
  • Brunner von Wattenwyl K (1893) Révision du Système des Orthoptères et description des espèces rapportées par M. Leonardo Fea de Birmanie. Annali del Museo Civico di Storia Naturale Giacomo Doria, Genova 13(33): 1–230. https://doi.org/10.5962/bhl.title.5121
  • Chiquetto-Machado PI, Cancello EM (2021) Cladistic analysis of Paraphasma (Phasmatodea: Pseudophasmatidae) highlights the importance of the phallic organ for phasmid systematics. Zoological Journal of the Linnean Society, London 193: 158–198. https://doi.org/10.1093/zoolinnean/zlab004
  • Chopard L (1920) Recherches sur la conformation et le développement des derniers segments abdominaux chez les Orthoptères. Imprimerie Oberthur, Rennes, 352 pp. https://doi.org/10.5962/bhl.title.50305
  • Cumming RT, Bank S, Bresseel J, Constant J, Le Tirant S, Dong Z, Sonet G, Bradler S (2021) Cryptophyllium, the hidden leaf insects – descriptions of a new leaf insect genus and thirteen species from the former celebicum species group (Phasmatodea, Phylliidae). ZooKeys 1018: 1–179. https://doi.org/10.3897/zookeys.1018.61033
  • Ghirotto VM (2021) Unmasking a master of camouflage: The rich morphology, taxonomy, and biology of the Brazilian stick insect Canuleius similis (Phasmatodea: Heteronemiidae), with general considerations on phasmid genitalia. Zoologischer Anzeiger 292: 30–57. https://doi.org/10.1016/j.jcz.2021.02.009
  • Gray GR (1835) Synopsis of the species of insects belonging to the family of Phasmidae. Longman, Rees, Orme, Brown, Green and Longman, London, 48 pp. https://doi.org/10.5962/bhl.title.8697
  • Heleodoro RA, Rafael JA (2019) Is the Phasmatodea male genitalia useful for systematics? A case study in Creoxylus and Prexaspes (Insecta: Phasmatodea) from the Brazilian Amazon Basin. Zoologischer Anzeiger 278: 66–79. https://doi.org/10.1016/j.jcz.2018.11.003
  • Helm C, Treulieb S, Werler K, Bradler S, Klass KD (2011) The male genitalia of Oxyartes lamellatus – phasmatodeans do have complex phallic organs (Insect: Phasmatodea). Zoologischer Anzeiger 250: 223–245. https://doi.org/10.1016/j.jcz.2011.04.005
  • Hennemann FH (2007) Notes on the genera Andropromachus Carl, 1913 and Spinohirasea Zompro, 2001. Phasmid Studies 15: 15–26.
  • Hennemann FH, Conle OV (2008) Revision of Oriental Phasmatodea: the tribe Pharnaciini, Günther, 1953, including the description of the world’s longest insect, and a survey of the family Phasmatidae Gray, 1835 with keys to the subfamilies and tribes (Phasmatodea: Anareolatae: Phasmatidae). Zootaxa 1906: 1–316. https://doi.org/10.11646/zootaxa.1906.1.1
  • Ho GWC (2018) New taxa of Necrosciinae from Vietnam (Phasmatodea: Diapheromeridae). Zoological Systematics 43(2): 178–189.
  • Kirby WF (1904) A Synonymic Catalogue of Orthoptera. 1. Orthoptera Euplexoptera, Cursoria et Gressoria. (Forficulidae, Hemimeridae, Blattidae, Mantidae, Phasmidae). British Museum, London, 501 pp.
  • Otte D, Brock PD (2005) Phasmida Species File. Catalog of Stick and Leaf Insects of the world, 2nd edn. The Insect Diversity Association and the Academy of Natural Sciences, Philadelphia, 414 pp.
  • Pantel J (1890) Notes orthopterologiques. II. Les phasmides d’Europe et des pays limitrophes. Anales de la Sociedad Española de Historia Natural 19: 371–404.
  • Pantel J (1915) Notes orthoptérologiques. VI. Le “vomer sousanal” n’est pas le “titillateure”; étude des segments abdominaux et principalement du segment terminal des mâles, chez les Phasmides. Annales de la Societé Entomologique de France 84: 173–243.
  • Ragge DR (1955) The wing-venation of the Orthoptera Saltatoria with notes on dictyopteran wing-venation. British Museum, London, 159 pp.
  • Redtenbacher J (1906) Die Insektenfamilie der Phasmiden. I. Phasmidae Areolatae. Leipzig, 180 pp.
  • Redtenbacher J (1908) Die Insektenfamilie der Phasmiden. III. Phasmidae Anareolatae (Phibalosomini, Acrophyllini, Necrosciini). Leipzig, 339–589.
  • Seow-Choen F (2016) A taxonomic guide to the stick insects of Borneo including new genera and species. Natural History Publications (Borneo), Kota Kinabalu, 454 pp.
  • Seow-Choen F (2017) A taxonomic guide to the stick insects of Singapore. Natural History Publications (Borneo), Kota Kinabalu, 165 pp.
  • Seow-Choen F (2018) A taxonomic guide to the stick insects of Sumatra. Volume 1. Natural History Publications (Borneo), Kota Kinabalu, 721 pp.
  • Simon S, Letsch H, Bank S, Buckley TR, Donath A, Liu S, Machida R, Meusemann K, Misof B, Podsiadlowski L, Zhou X, Wipfler B, Bradler S (2019) Old World and New World Phasmatodea: Phylogenomics Resolve the Evolutionary History of Stick and Leaf Insects. Frontiers in Ecology and Evolution 7: 1–14. https://doi.org/10.3389/fevo.2019.00345
  • Shorthouse DP (2010) SimpleMappr, an online tool to produce publication-quality point maps. http://www.simplemappr.net [Accessed 11.I.2020]
  • Snodgrass RE (1937) The male genitalia of orthopteroid insects. Smithsonian Miscellaneous Collection 96: 1–107.
  • Vallotto D, Bresseel J, Constant J, Gottardo M (2016a) Morphology of the terminalia of the stick insect Dajaca napolovi from Vietnam (Insecta: Phasmatodea). Entomological Science 19: 376–382. https://doi.org/10.1111/ens.12209
  • Vallotto D, Bresseel J, Heitzmann T, Gottardo M (2016b) A black-and-red stick insect from the Philippines – observations on the external anatomy and natural history of a new species of Orthomeria. ZooKeys 559: 35–57. https://doi.org/10.3897/zookeys.559.6281
  • Westwood JO (1848) The cabinet of Oriental Entomology. Oxford Digital Library, 88 pp.
  • Walker EM (1922) The terminal structures of orthopteroid insects: a phylogenetic study (Part II). Annals of the Entomological Society of America 15: 1–76. https://doi.org/10.1093/aesa/15.1.1
  • Zompro O (2002) Spinohirasea crassithorax, n. gen. n. sp., eine neue Stabschrecke aus Vietnam (Phasmatodea: Phasmatidae: Lonchodinae: Menexenini). Bonner Zoologische Beiträge 50(1–2): 67–72.
  • Zompro O (2004) Revision of the genera of the Areolatae, including the status of Timema and Agathemera (Insecta, Phasmatodea). Abhandlungen des Naturwissenschaftlichen Vereins Hamburg, (NF) 37, Verlag Goecke & Evers, 327 pp.