Cryptophyllium, the hidden leaf insects – descriptions of a new leaf insect genus and thirteen species from the former celebicum species group (Phasmatodea, Phylliidae)

Abstract

While the leaf insects (Phylliidae) are a well-supported group within Phasmatodea, the genus Phyllium Illiger, 1798 has repeatedly been recovered as paraphyletic. Here, the Phyllium (Phyllium) celebicum species group is reviewed and its distinctiveness from the remaining Phylliini genera and subgenera in a phylogenetic context based on morphological review and a phylogenetic analysis of three genes (nuclear gene 28S and mitochondrial genes COI and 16S) from most known and multiple undescribed species is shown. A new genus, Cryptophylliumgen. nov., is erected to partially accommodate the former members of the celebicum species group. Two species, Phyllium ericoriaiHennemann et al., 2009 and Phyllium bonifacioi Lit & Eusebio, 2014 morphologically and molecularly do not fall within this clade and are therefore left within Phyllium (Phyllium). The transfer of the remaining celebicum group members from Phyllium Illiger, 1798 to this new genus creates the following new combinations; Cryptophyllium athanysus (Westwood, 1859), comb. nov.; Cryptophyllium celebicum (de Haan, 1842), comb. nov.; Cryptophyllium chrisangi (Seow-Choen, 2017), comb. nov.; Cryptophyllium drunganum (Yang, 1995), comb. nov.; Cryptophyllium oyae (Cumming & Le Tirant, 2020), comb. nov.; Cryptophyllium parum (Liu, 1993), comb. nov.; Cryptophyllium rarum (Liu, 1993), comb. nov.; Cryptophyllium tibetense (Liu, 1993), comb. nov.; Cryptophyllium westwoodii (Wood-Mason, 1875), comb. nov.; Cryptophyllium yapicum (Cumming & Teemsma, 2018), comb. nov.; and Cryptophyllium yunnanense (Liu, 1993), comb. nov. The review of specimens belonging to this clade also revealed 13 undescribed species, which are described within as: Cryptophyllium animatumgen. et sp. nov. from Vietnam: Quang Nam Province; Cryptophyllium bankoigen. et sp. nov. from Vietnam: Quang Ngai, Thua Thien Hue, Da Nang, Gia Lai, Quang Nam, and Dak Nong Provinces; Cryptophyllium bollensigen. et sp. nov. from Vietnam: Ninh Thuan Province; Cryptophyllium daparogen. et sp. nov. from China: Yunnan Province; Cryptophyllium echidnagen. et sp. nov. from Indonesia: Wangi-wangi Island; Cryptophyllium faulknerigen. et sp. nov. from Vietnam: Quang Ngai and Lam Dong Provinces; Cryptophyllium icarusgen. et sp. nov. from Vietnam: Lam Dong and Dak Lak Provinces; Cryptophyllium khmergen. et sp. nov. from Cambodia: Koh Kong and Siem Reap Provinces; Cryptophyllium limogesigen. et sp. nov. from Vietnam: Lam Dong, Dak Lak, and Dak Nong Provinces; Cryptophyllium liyananaegen. et sp. nov. from China: Guangxi Province; Cryptophyllium nuichuaensegen. et sp. nov. from Vietnam: Ninh Thuan Province; Cryptophyllium phamigen. et sp. nov. from Vietnam: Dong Nai and Ninh Thuan Provinces; and Cryptophyllium wennaegen. et sp. nov. from China: Yunnan Province. All newly described species are morphologically described, illustrated, and molecularly compared to congenerics. With the molecular results revealing cryptic taxa, it was found necessary for Cryptophyllium westwoodii (Wood-Mason, 1875), comb. nov. to have a neotype specimen designated to allow accurate differentiation from congenerics. To conclude, male and female dichotomous keys to species for the Cryptophylliumgen. nov. are presented.

A tree of leaves: Phylogeny and historical biogeography of the leaf insects (Phasmatodea: Phylliidae)

“…2 – 5 ). However, Chitoniscus and Phyllium are recovered as paraphyletic, which was already shown in previous studies based on molecular data 24 , 25 , 29 , 40 , 41 . The Chitoniscus spp.…”

“…Of the five Phyllium species available on GenBank, which were not processed by and included in Cumming et al 38 , 40 , only one identification could be confirmed as correct ( P. giganteum ). The Phyllium celebicum from Thailand 29 was identified and bred in captivity as such, despite the fact that the type species is from Sulawesi.…”

“…The cryptic diversity of leaf insects constitutes yet another problem: Several specimens that are morphologically indistinguishable are recovered as distinct species in the molecular phylogeny (e.g. P. ericoriai , P. mabantai ; see also Cumming et al 40 ). However, only the inclusion of type material in the molecular analysis allows to reveal which specimens can be assigned to a described species.…”

“…Cryptophyllium appears to have dispersed in the Early Miocene (26.3–16.8 mya) across Sundaland to mainland Asia before high sea-level stands disallowed the transgression of the Isthmus of Kra for a prolonged period of time 96 . Their distribution expanded to India and Nepal as well as to Southern China 40 . Yet, one lineage migrated southward to Wallacea via Sundaland by dispersing over the narrowing Makassar Strait to Sulawesi ( C. celebicum + C. echidna ), corroborating the permeability of Wallace’s Line in the Late Miocene 95 , 97 .…”

“…Both Phyllium and Pulchriphyllium have undergone further intra-generic systematisation and were classed in several species groups by Hennemann et al 35 . One of these species groups was recently revealed to be distinct to the remaining phylliids and was therefore transferred to the newly erected genus Cryptophyllium 40 . Molecular analyses preceding this study had already repeatedly demonstrated that Phyllium (and Chitoniscus ) are paraphyletic and that the Phylliidae are in need of revision 24 , 25 , 29 , 40 .…”