Phyllium (Phyllium) jacobsoni Rehn & Rehn, 1934

Cumming, Royce T., Bank, Sarah, Le Tirant, Stephane & Bradler, Sven, 2020, Notes on the leaf insects of the genus Phyllium of Sumatra and Java, Indonesia, including the description of two new species with purple coxae (Phasmatodea, Phylliidae), ZooKeys 913, pp. 89-126 : 89

Phyllium (Phyllium) jacobsoni Rehn & Rehn, 1934 Figure 5A-E

Distribution.

Indonesia: Eastern Java (Nongkodjadjar [type locality]); Eastern Java, Mt. Argopuro; Western Java, Mt. Halimun (Figure 4 ).

Discussion.

With the description of the very morphologically similar Phyllium gardabagusi sp. nov., also from Java, the numerous localities noted within Hennemann et al. (2009) cannot be confirmed as Phyllium jacobsoni . This is because the only clear morphological feature to differentiate between these two populations is the coxae color, which can fade in specimens which were not well preserved. Therefore, we only list the localities where we have been able to confirm specimens as Phyllium jacobsoni . Nevertheless, with this species confirmed from both West and East Java, it is likely the species is found throughout the island.

Differentiation.

This is the only species in the clade that can easily be differentiated morphologically from other clade members. The coxae color in P. jacobsoni is white (see Figure 5C, D ) compared to a distinct and dark purple in the other three clade members (Table 1 ). This purple color is easier to view in females and can only be faintly seen on very well preserved or live males. In any discolored male it is impossible to differentiate the species by looking at the coxae because the white and faint purple color do not preserve well and cannot be differentiated on poor quality specimens. It is fortunate that the holotype for Phyllium jacobsoni is a female specimen as it can clearly be seen on the holotype female that this was not the sympatric species Phyllium gardabagusi sp. nov. with purple coxae and is instead a specimen with white coxae which defines Phyllium jacobsoni .

On average P. jacobsoni tend to be smaller individuals, but as with the other species in the clade there were significant outliers that made the range of sizes overlap with the other species significantly (Table 1 ). Phyllium jacobsoni newly hatched nymphs (Figure 5E ) appear to be the most variable in coloration of the four clade B members. Phyllium jacobsoni overall coloration ranges from reddish brown to dark brown (in the other three members dark brown to black), and on P. jacobsoni the white transverse band on the meso- and metafemora can be a solid line (like in the other three clade B species) or can occasionally be a broken white line (but this is a less common form).

Figures

Figure 4. Distribution map for Phyllium giganteum (Borneo, Peninsular Malaysia, Sumatra, and Java), Phyllium hausleithneri (Peninsular Malaysia), Phyllium nisus sp. nov. (Sumatra), and Phyllium gardabagusi sp. nov. (Java) and Phyllium jacobsoni (Java).

Figure 5. Phyllium jacobsoni live captive bred individuals, photos courtesy of Bruno Kneubuehler. A Female B male C male ventral view of coxae D female ventral view of coxae E freshly hatched nymph.