Phyllium dardanus Westwood, 1859 (OUMNH; Fig. 20)

Cumming, Royce T., Le Tirant, Ste ́ phane, Linde, Jackson B., Solan, Megan E., Foley, Evelyn Marie, Eulin, Norman Enrico C., Lavado, Ramon, Whiting, Michael F., Bradler, Sven & Bank, Sarah, 2023, On seven undescribed leaf insect species revealed within the recent " Tree of Leaves " (Phasmatodea, Phylliidae), ZooKeys 1173, pp. 145-229 : 145

Phyllium dardanus Westwood, 1859 (OUMNH; Fig. 20)

Phyllium gelonus Gray, 1843 (NHMUK; lost according to Brock et al. 2022).

Differentiation.

Female Pulchriphyllium crurifolium stat. rev., comb. nov. are the easiest to differentiate from the other " Pulchriphyllium bioculatum "-like species by comparing the profemoral exterior lobe shape. In Pulchriphyllium crurifolium stat. rev., comb. nov. the anterior margin of the exterior profemoral lobe is nearly straight, giving the lobe a boxy appearance (Fig. 21A ) vs the other " Pulchriphyllium bioculatum "-like species which have this margin notably rounded, giving the lobe a slight recurve appearance (Fig. 21B ).

Males are difficult to differentiate, and even after reviewing numerous specimens in series there appears to be enough intraspecific variation to make reliable differentiation impossible. On average males tend to have slightly narrower profemoral exterior lobes with a strongly obtuse angle (Fig. 22B ), but some of the other " Pulchriphyllium bioculatum "-like species can sometimes exhibit a similar lobe shape.

Eggs of Pulchriphyllium crurifolium stat. rev., comb. nov. are slightly smaller than the other " Pulchriphyllium bioculatum "-like species and have a great deal more raised nodes throughout the surfaces (Fig. 23D-F ).

To date, the authors have yet to see an observation of a freshly hatched nymph of this taxon. With how unique and species-specific congenerics are (Fig. 8 ), it is likely that this species can be additionally differentiated by the freshly hatched nymph habitus.

Distribution.

(Fig. 15A ) At present known from three of the islands of the Seychelles: Mahé, Praslin, and La Digue (see Suppl. material 1 for list of observations).

Remarks.

This taxon was originally described as a unique species from the Seychelles ( Audinet-Serville 1838); however, over the decades this taxon has been treated either as a synonym, subspecies, or local form of " Pulchriphyllium bioculatum " ( Giglio-Tos 1910; Brock 1995; Hennemann et al. 2009). At present molecular data are lacking for this taxon, but there are numerous specimens in historic collections and recent citizen science observations (Fig. 22 ) which illustrate a consistent and unique morphology. Biogeographically it is likely that this species is sister to the Indian or Sri Lankan species as other organisms are known to have utilized the Maldives archipelago from the Indian sub-continent at some point during low sea levels of the past to colonize the Seychelles ( O’Brien 2011; Bernardes et al. 2021).

In the decades following the description of Pulchriphyllium crurifolium stat. rev., comb. nov., there were several other taxa described from the Seychelles, but since their description they have been synonymized with Pulchriphyllium bioculatum ( Brock et al. 2022). Of the three taxa described from the Seychelles ( Phyllium crurifolium , Phyllium dardanus , and Phyllium gelonus ), only type specimens of Phyllium crurifolium and Phyllium dardanus remain (the type of Phyllium gelonus is reported as lost according to Brock et al. 2022). Thankfully, the syntype series of Pulchriphyllium crurifolium stat. rev., comb. nov. (the senior synonym) has survived within the OUMNH collection. Within the original description, the syntypes are noted as: "East Indies. The male labeled from the Seychelles Islands by Latreille. Collection of M. le comte Dejean. I have both sexes" ( Audinet-Serville 1838). Of these specimens, the male from the Latrielle collection (Fig. 19D ), and three specimens labeled as from Serville (Fig. 19A-C ) have been traced within the OUMNH collection. Unfortunately, any syntypes which were within the "Collection of M. le comte Dejean" (Pierre François Marie Auguste Dejean; 1780-1845) could not be traced. In choosing the specimen to be designated as the lectotype, we chose the specimen in question following several lines of thought. First, we wish to designate a female specimen as males are morphologically indistinguishable from several congenerics. Second, following chapter 16, article 74E of the ICZN Code ( ICZN 1999) we chose the female specimen with the explicit collection data of “Seychelles” (Fig. 19B ).

The eggs of Pulchriphyllium crurifolium stat. rev., comb. nov. are very similar to most Pulchriphyllium species therefore this species adds credibility to the phylogeny of Büscher et al. (2023). Within Büscher et al. (2023) the Pulchriphyllium are primarily characterized as "type 7" eggs (defined as having "exochorionic structures fused to dense fins"). The only Pulchriphyllium species which lacks this type is Pulchriphyllium giganteum which is sister species to all other Pulchriphyllium . Even though Pulchriphyllium crurifolium stat. rev., comb. nov. could not be included within our phylogeny (Fig. 2 ), based upon adult and egg morphology this species likely is more closely related to one of the other " Pulchriphyllium bioculatum -like" species.

Figures

Figure 2. Phylogenetic tree of the Phylliidae based on six nuclear and mitochondrial loci with a focus on Phyllium and Pulchriphyllium (please refer to Suppl. material 4 for the complete tree). Ultrafast bootstrap support values are depicted at each node. Specimens in green font are in addition to the already existing tree inferred by Bank et al. (2021). Highlighted in green boxes are the seven newly described species.

Figure 8. Illustrations of the freshly hatched nymph coloration for herein referenced species A Phyllium ortizi sp. nov. (Mindanao) B Phyllium mabantai (Mindanao) C Phyllium samarense sp. nov. (Samar) D Pulchriphyllium bioculatum (West Malaysia) E Pulchriphyllium anangu sp. nov. (Southwest India) F Pulchriphyllium agathyrsus (Sri Lanka) G Pulchriphyllium giganteum (West Malaysia) H Pulchriphyllium bhaskarai sp. nov. (Java). Illustrations by scientific illustrator Liz Sisk (Washington D. C., USA).

Figure 15. Distribution map for the herein discussed Pulchriphyllium species with known records plotted. For data on the distribution points used for this map, see Suppl. material 1 A distribution of the " Pulchriphyllium bioculatum - like species " B distribution of the Pulchriphyllium species from mainland Asia with a boxy abdominal shape (inset outline in A). Abbreviations: KH, Cambodia; LA, Laos; TH, Thailand; VN, Vietnam.

Figure 19. Pulchriphyllium crurifolium stat. rev., comb. nov. specimens which, based upon their labels, appear to be the syntype specimens designated by Audinet-Serville in 1838 A paralectotype, male, dorsal habitus, associated data labels to the right B lectotype, female, dorsal habitus, associated data labels to the right C paralectotype, female, dorsal habitus, associated data labels to the left and below D paralectotype, male, dorsal habitus, associated data labels to the left and below. Photographs by Robert Douglas, courtesy of Oxford University Museum of Natural History.

Figure 21. Adult female profemoral lobes from various Pulchriphyllium species for comparison A Pulchriphyllium crurifolium stat. rev., comb. nov. (NHMUK) B Pulchriphyllium bioculatum from West Malaysia (Coll RC 16 - 038) C Pulchriphyllium scythe stat. rev., comb. nov. from Sylhet, Bangladesh (OUMNH) D Pulchriphyllium pulcrifolum from Java, Indonesia (Coll RC 16 - 024) E Pulchriphyllium bhaskarai sp. nov. from Java, Indonesia (MZPW).

Figure 22. Live Pulchriphyllium crurifolium stat. rev., comb. nov. A adult female, dorsal habitus, observed September 2019 at Sans Souci, Mahe, Seychelles, by Juan Jose Areso uploaded by iNaturalist user @ liahg (Amalia Herrera Grau) (https: // www. inaturalist. org / observations / 76082181) B adult male, dorsal habitus, observed December 2006 at Grand' Anse, Mahe, Seychelles by iNaturalist user @ thierrycordenos (https: // www. inaturalist. org / observations / 22992534). Both images uploaded to iNaturalist and used under license (CC BY-NC 4.0).

Figure 23. Eggs from Pulchriphyllium bioculatum - like species, where the eggs are known A-C Pulchriphyllium bioculatum from West Malaysia (Coll RC # 18 - 042) D-F Pulchriphyllium crurifolium stat. rev., comb. nov. from the Seychelles (Coll RC # 18 - 233) G-I Pulchriphyllium agathyrsus from Sri Lanka (Coll RC # 18 - 232). Top row, dorsal view. Middle row, lateral view. Bottom row, anterior view.