Phyllium cayabyabi Cumming, Foley, Hennemann, Le Tirant & Büscher, 2025

Cumming, Royce T., Foley, Evelyn Marie, Hennemann, Frank H., Le Tirant, Stephane, Daawia,, Warikar, Evie Lilly, Yando, Heron, Suhartawan, Bambang, Henze, Katharina, Büscher, Thies H. & Bank, Sarah, 2025, A deeper look into the diversity of Phyllium leaf insects from Indonesia: seven new species and two unique egg morphologies (Phasmatodea, Phylliidae), ZooKeys 1256, pp. 317-370 : 317-370

Phyllium cayabyabi Cumming, Foley, Hennemann, Le Tirant & Büscher sp. nov.

Figs 6 , 7 , 8 , 9 , 10

Type material.

Holotype ( ♀): Indonesia • North Kalimantan, Malinau Regency, Tanjung Lapang Village , August 2020, Coll RC # 20-135 [ IMQC] . Paratypes: (2 ♀♀, 1 ♂, 1 ♀ nymph, 3 eggs): ( 1 ♀ nymph, 1 ♂) Indonesia • North Kalimantan, Malinau Regency, Tanjung Lapang Village , August 2020 (1 ♂) Coll RC # 20-137; ♀ nymph # 20-136 [ Coll RC] . ( 2 eggs) Indonesia • North Kalimantan, Malinau Regency, Tanjung Lapang Village , August 2020; # 20-138, # 20-139 [ Coll RC] ; ( 1 egg): Indonesia • North Kalimantan, Malinau Regency, Tanjung Lapang Village , August 2020 [ Coll TB] ; ( 2 ♀♀): Indonesia • North Kalimantan, Malinau Regency, Tanjung Lapang Village , August 2020 [ IMQC] .

Differentiation.

Female Phyllium cayabyabi sp. nov. (Fig. 6 ) are most morphologically similar to Phyllium gantungense and Phyllium arthurchungi (likely also similar to the Phyllium cummingi female, but that sex is not yet known at this time so no direct comparison can be made) due to similar femoral lobe shapes / serration and boxy abdominal morphology. Phyllium cayabyabi sp. nov. can be differentiated from Phyllium gantungense by the ventral coxae coloration, as Phyllium gantungense has distinctly black ventral coxae coloration while Phyllium cayabyabi sp. nov. does not have distinct black spots (unfortunately the exact color of the ventral meta- and mesocoxae cannot be determined as the type specimens were poorly preserved and the coloration did not survive well enough to discern). Phyllium cayabyabi sp. nov. can be differentiated from Phyllium arthurchungi by the arrangement of nodes along the mesoprescutum as Phyllium arthurchungi has the nodes exclusively situated along the sagittal plane in a tight line, while Phyllium cayabyabi sp. nov. has the nodes only generally along the sagittal plane, meandering side to side of the central line (Fig. 6 E ).

Male Phyllium cayabyabi sp. nov. (Fig. 7 ) are similar to Phyllium arthurchungi , Phyllium cummingi , and Phyllium gantungense due to similar tegmina venation / length, the thorax shape and spination, the lobes of the legs, and the broad boxy bodies. Phyllium cayabyabi sp. nov. is most similar to Phyllium arthurchungi and the only feature we have found that might differentiate them is the abdominal shape, with Phyllium arthurchungi having a wider segment VI, and a slight undulation to segment VII, vs Phyllium cayabyabi sp. nov. which has a slightly narrower abdomen and segment VII with straight margins. Phyllium cayabyabi sp. nov. can be differentiated from Phyllium cummingi and Phyllium gantungense by abdominal segment V, which is Phyllium cayabyabi sp. nov. has widening margins, but in the other two species the margins are parallel.

Eggs of Phyllium cayabyabi sp. nov. (Fig. 8 ) are unlike any known phylliid species egg due to the autapomorphic traits of spatulate pinnae with short chorionic outgrowths (Fig. 9 B ) and hollow, columnar pinnae densely covering the entire egg surface (Fig. 9 D ). While the above discussed species males and females all look very similar, only the eggs of Phyllium cayabyabi sp. nov. allow for reliable morphological differentiation. To contrast, the eggs of closely related species Phyllium gantungense and Phyllium arthurchungi (Fig. 1 ) both have large pits along their lateral surfaces arranged in a 2 × 4 pattern, completely unlike Phyllium cayabyabi sp. nov. eggs.

Description.

Female. Coloration. Coloration description is based upon photos of the type material shared with the authors of the live specimens prior to preservation. The general coloration is pale green throughout. The only areas that differ are the antennae that are somewhat orange / tan and some of the more prominent veins of the tegmina which are brown.

Morphology. Head capsule longer than wide, with a vertex that is somewhat roughly textured, and marked with minimal granulation along the posterior (Fig. 6 A ). The posteromedial tubercle is present, singularly lobed, but not very prominent (Fig. 6 A ). Frontal convexity is broad and ending in a blunted point; there are several short setae across the surface. Compound eyes slightly protruding from the head capsule, not bulbous, taking up ~ ¼ of the head capsule lateral margins (Fig. 6 A ). Ocelli absent. Antennal fields slightly wider than the first antennomere width.

Antennae consist of ten segments, with the terminal segment approx. the same length as the preceding 2 ½ segments’ lengths combined (Fig. 10 A ). Antennomeres I – VIII are smooth, and sparsely marked with short setae, the terminal two antennomeres are covered in short, dense setae, giving these segments a fuzzy appearance (Fig. 10 A ). Stridulatory file of antennomere III has 33–35 teeth, and the stridulatory ridge has 33 or 34 teeth (Fig. 10 B ).

Thorax. Pronotum with slightly concave anterior margin and lateral margins that anteriorly start wide, angle inward strongly to the posterior margin which is ~ ½ the width of the anterior margin (Fig. 6 A ). The pronotum anterior margin and the lateral margins have prominent rims, while the posterior margin is less prominent. The pronotum surface is relatively smooth, with only a prominent pit in the center and a distinct furrow anterior to the center (Fig. 6 A ). Prosternum and the anterior 1 / 3 of the mesosternum are covered with irregularly spaced granulation; the remainder of the mesosternum and the metasternum are slightly wrinkled but lack nodes. Mesoprescutum slightly longer than wide, lateral rims with six or seven small tubercles (Fig. 6 E ). Mesoprescutum anterior rim prominently raised into a distinct and finely pointed sagittal spine (Fig. 6 C ). Mesoprescutum surface slightly lumpy and only slightly raised along the sagittal crest, which has several haphazardly located nodes along its length, not perfectly aligned along the plane (Fig. 6 E ). Mesopleurae narrow for the anterior 1 / 3 until they begin to diverge and angle prominently away with nearly straight margins (Fig. 6 E ). Mesopleuron lateral margin with six or seven medium sized nodes, mostly situated on the anterior 1 / 2, and the posterior 1 / 2 only has some minimal granulation (Fig. 6 E ). Face of the mesopleuron slightly wrinkled (Fig. 6 E ).

Wings. Tegmina long, reaching the anterior margin of abdominal segment VIII. Tegmina venation; the subcosta ( Sc) is the first vein in the forewing, running parallel with the margin for the first 1 / 2, and then bending and running towards the margin. The subcosta runs for ~ ¼ of the tegmina length. The radius (R) spans the central portion of the forewing with two subparallel (slightly diverging) branched veins; the first radius ( R 1) branches ~ ¼ of the way through the wing length and terminates ~ 1 / 3 of the way through the wing length; the radial sector ( Rs) branches ~ 1 / 3 of the way through the wing length and terminates near the distal 1 / 3 of the wing length. There is a weak continuation of the radius following the prominent Rs branching which continues on as a short but distinct R – M crossvein that weakly connects the two veins. The media (M) is bifurcate with both the media anterior ( MA) and media posterior (MP) terminating near to the posterior of the tegmina. The cubitus ( Cu) is also bifurcate, branching near the posterior ¼ of the wing into the cubitus anterior ( CuA) and cubitus posterior ( CuP) which both terminate near the wing apex. The first anal vein ( 1 A) is simple and fuses with the cubitus ~ ¼ of the way through the tegmina length. Alae vestigial, only small nubs.

Abdomen. Abdominal segments II through the anterior ½ of IV gradually and uniformly diverging. The posterior ½ of segment IV through the anterior ½ of segment VII are only slightly diverging to the widest point of the abdomen. Abdominal segment VII is rounded ca 90 degrees with posterior margins angled almost directly inward where they meet the notably narrower segment VIII. Segments VIII – X have straight, converging margins ending in a broad rounded apex (Fig. 6 G ).

Genitalia. Subgenital plate starts at the anterior margin of tergum VIII, is moderately broad, and extends ¾ of the way onto tergum X. The shape is somewhat tiered into approximately three widths as it converges to a finely pointed apex (Fig. 6 F ). Gonapophyses VIII are long and not particularly broad, exceeding the apex of the abdominal tergum X slightly; gonapophyses IX are obstructed from view (Fig. 6 F ). Cerci flat, slightly broadening to the apical 1 / 3 into a somewhat blade-like end, with a slightly granular surface (Fig. 6 F ).

Legs. Profemoral exterior lobe broad and arching end to end, with a width slightly narrower than the width of the interior lobe (Fig. 6 A ). Margin of the profemoral exterior lobe slightly granular (Fig. 6 A ). Profemoral interior lobe slightly more than 2 × as wide as the greatest width of the profemoral shaft, approximately right angled, and marked with four large, triangular teeth with looping gaps between them, arranged in a two-wide gap-two pattern (Fig. 6 A ). Mesofemoral interior and exterior lobes approx. as wide as the mesofemoral shaft width. Mesofemoral exterior lobe with two small, distally pointing teeth on the distal ½ of the lobe with a wide gap between them. Mesofemoral exterior lobe is somewhat angled, not as smoothly arching as in the interior lobe. Mesofemoral interior lobe with six small, distally pointing teeth on the distal 2 / 3 of the lobe, with the teeth somewhat arranged into pairs. Metafemoral interior lobe arcs end to end, with the proximal 1 / 3 notably thinner and smooth and slightly widening out to the distal 2 / 3 which is wider and armed with seven or eight dulled, small teeth. Metafemoral exterior lobe lacks dentation, is thinner than the shaft width, and runs parallel with the shaft throughout its length. Protibia exterior lacking a lobe (Fig. 6 A ). Protibiae interior lobe spans the entire length of the protibiae (although the distal end is very thin and not prominent) and is ~ 1.5 × the width of the protibiae shaft itself. The lobe is roundly triangular with the widest portion near the middle, and the proximal end more distinct than the distal end. Mesotibiae and metatibiae simple, lacking exterior and interior lobes.

Measurements (mm). Holotype, female: body length (including cerci and head, excluding antennae): 85.9, length / width of head: 8.3 / 6.8, antennae: 4.4, pronotum: 5.9, mesonotum: 8.2, length of tegmina: 54.0, greatest width of abdomen: 36.7, profemora: 14.9, mesofemora: 13.5, metafemora: 17.1, protibia: 9.8, mesotibia: 10.5, metatibia: 15.0.

Male. Coloration. Coloration based upon the dead, dried type specimen which is somewhat discolored (Fig. 7 ). Overall coloration pale green / yellow throughout. The compound eyes are brownish-red, and the antennae are darker / gray. Protibia interior lobe and margin of the profemoral interior lobe with several brown / tan markings

Morphology. Head capsule slightly longer than wide, with a vertex that is slightly lumpy and marked throughout with a few small, widely distributed nodes (Fig. 7 A ). The posteromedial tubercle is singularly pointed, small, and not notably raised above the head capsule (Fig. 7 A, F ). Frontal convexities stout and bluntly pointed with a few sparse setae. Compound eyes large and bulbous, occupying ~ 2 / 5 of the head capsule lateral margins (Fig. 7 A ). There are three distinct ocelli raised above the capsule and located between the compound eyes (Fig. 7 A ).

Antennae (including the scapus and pedicellus) consist of 25 segments (Fig. 7 A ), all segments except the scapus and pedicellus and terminal five segments are covered in numerous setae where most are as long as the antenna segment is wide. The terminal five segments are covered in dense, short setae and the scapus and pedicellus are nearly completely bare with only a few sparse setae.

Thorax. Pronotum with slightly convex anterior margin and straight lateral and posterior margins. Posterior margin is ~ ½ the width of the anterior margin. The anterior margin is well-developed, the lateral margins are moderately formed, and the posterior margin is weakly formed (Fig. 7 D ). Face of the pronotum is marked by a distinct pit in the center, a sagittal furrow on the anterior ½, and slight perpendicular furrows originating from the central pit. The pronotum surface is only slightly lumpy but lacking distinct granulation (Fig. 7 D ). Prosternum surface is lumpy with small nodes. Mesosternum surface anterior 1 / 3 marked heavily with granulation, the remainder of the mesosternum surface is wrinkled but lacks notable nodes. Metasternum surface mostly wrinkled throughout, and the anterior margin central area is additionally marked with granulation. Mesoprescutum longer than wide, with lateral margins that are slightly converging to the posterior margin which is only slightly narrower than the anterior margin (Fig. 7 D ). Lateral margins of the mesoprescutum with five or six moderately formed tubercles of a somewhat uniform size (Fig. 7 D ). Mesoprescutum surface wrinkled and slightly raised along the sagittal plane which is marked with four or five distinct nodes and the remainder of the surface has slight granulation (Fig. 7 D, F ). Mesoprescutum anterior rim moderately formed with a distinct sagittal spine, and the remainder of the rim surface is slightly wrinkled (Fig. 7 D, F ). Mesopleurae begin on the anterior mesoprescutum margin, begin very narrow, and diverge slowly at a gradually increasing angle from the anterior to the posterior but are never notably wide throughout their length (Fig. 7 D ). Mesopleuron lateral margin with four or five small tubercles and a few small nodes interspersed throughout the length except for the posterior 1 / 3 of the margin which is relatively smooth (Fig. 7 D ). Mesopleuron face moderately wrinkled and marked by a distinct pit near the center.

Wings. Tegmina moderate length, extending ¾ of the way onto abdominal segment IV. Tegmina wing venation: the subcosta ( Sc) is the first vein, is simple, and terminates ~ 1 / 3 of the way through the overall wing length. The radius (R) spans nearly the entire length of the tegmina with the first radius ( R 1) branching ~ 1 / 3 of the way through the tegmina length and terminates on the margin slightly less than ½ through the length. There is also a second radius ( R 2) that originates near the middle, and a third radius ( R 3) which originates ~ 3 / 5 of the way through the wing length. The radial sector runs towards the wing apex, but near the terminal 1 / 3 angles towards the margin, slightly away from the apex. The media (M) spans the entire length of the tegmina running side by side along the radius / radial sector for most of the length, with a first media posterior ( MP 1) branching off near the midlength of the tegmina and running angled towards the cubitus, a second media posterior ( MP 2) branches off ~ 3 / 5 of the way through the length, and the media anterior ( MA) runs straight to the tegmina apex. The cubitus ( Cu) cuts across the tegmina to the margin ~ 1 / 3 of the way through the length and runs along the edge of the tegmina where the media posterior veins fuse with it and as the cubitus reaches the apex it fades. The first anal ( 1 A) vein terminates upon reaching the cubitus ~ 1 / 3 of the way through the tegmina length. Alae well-developed in an oval fan configuration, long, reaching to the middle of abdominal segments VIII. Ala wing venation hidden from view due to the alae being folded in the type specimen.

Abdomen. Lateral margins of abdominal segment II parallel, III diverging slightly, IV diverging at a more prominent angle for the anterior 2 / 3 and then slightly less strongly for the posterior 1 / 3, V slightly diverging, VI diverges slightly for the anterior 2 / 3 to the widest point of the abdomen, then converges on the posterior 1 / 3, followed by all preceding segments converging strongly at first and then more gradually towards the apex (segment X), which is broad and rounded.

Genitalia. Poculum broad and ends with a flat, blunted apex that slightly passes the anterior margin of abdominal segment X with a margin that is nearly straight (Fig. 7 E ). Cerci long, slender, and nearly flat, with subparallel margins, with ~ 2 / 3 of their length extending from under abdominal segment X. The cerci surfaces are slightly granular and there are numerous short setae along the margins (Fig. 7 E ). Vomer broad and stout with straight sides evenly converging to the apical hook which is thick and has a singular point (Fig. 7 E ).

Legs. The profemoral exterior lobe arcs end to end and is narrow, approx. the same width as the profemoral shaft at its widest. The profemoral exterior lobe margin is slightly granular (Fig. 7 A ). The profemoral interior lobe is obtusely triangular and at its greatest width it is ~ 2 × the greatest width of the profemoral shaft. The profemoral interior lobe is ornamented on the distal ½ with four serrate teeth arranged as small tooth-large tooth-wide gap-large tooth-small tooth (Fig. 7 A ). Mesofemoral exterior lobe and interior lobe are of similar shapes and widths, both arching end to end but are slightly wider on the distal 2 / 3. Both lobes at their widest are approx. as wide as the mesofemoral shaft width. The only notable difference between these two lobes is that the interior lobe has five small teeth on the distal 1 / 2. The mesofemoral exterior lobe is unornamented. Metafemoral exterior lobe lacks dentition and has a straight, thin margin along the metafemoral shaft. Metafemoral interior lobe is approx. as wide as the metafemoral shaft width, arcs end to end, but is thinner on the proximal 1 / 3, the distal 1 / 3 is marked with six small serrate teeth. Protibiae lacking exterior lobe, interior lobe mostly situated in the middle of the shaft with the distal end without lobe and the proximal end very thin. The protibial interior lobe is a small, rounded triangle with the widest portion just distal to the midlength (Fig. 7 A ). Meso- and metatibiae simple, lacking lobes completely.

Measurements of paratype male [mm]. Length of body (including cerci and head, excluding antennae) 65.4, length / width of head 4.4 / 3.8, antenna 26.2, pronotum 3.5, mesonotum 4.9, length of tegmina 24.5, length of alae 42.4, greatest width of abdomen 20.2, profemora 10.4, mesofemora 10.0, metafemora 11.0, protibiae 6.5, mesotibiae 7.2, metatibiae 10.8.

Eggs (Figs 8 , 9 ). The overall egg shape is difficult to discern fully due to the long and dense pinnae, but appears to be somewhat reniform, with the ventral surface protruding slightly and the dorsal surface slightly curved inward. The entire egg capsule is covered by spatulate pinnae with short chorionic outgrowths (Fig. 9 B ) and hollow, columnar pinnae densely covering the entire egg surface (Fig. 9 D ). These two types are somewhat interspersed, but the roughly textured spatulate pinnae are more prominent along the anterior and posterior margins, while the smoother columnar pinnae are more prominent on the flat surfaces. The operculum is nearly circular and rimmed by the roughly textured spatulate pinnae which are slightly shorter than the pinnae on the remainder of the egg capsule. The micropylar plate is mostly obstructed from view but appears to be thin and only situated in the middle of the egg capsule. The capsule surface below the dense pinnae appears to be rather smooth and paler in color than the dark brown pinnae covering the surface.

Measurements including the extended pinnae [mm].

Length (including operculum expansion): 6.0–6.6; maximum width of capsule when viewed from lateral aspect 4.8–5.5; length of micropylar plate 2.8–3.4.

Etymology.

Patronym; named to honor Victor Cayabyab, a collaborator of the Montreal Insectarium for the last 30 years and a very good friend to the fourth author.

Distribution.

At present only known from the type locality of Malinau, in North Kalimantan, Indonesia (Fig. 2 ).

Figures

Figure 1. Maximum Likelihood tree with focus on the phylogenetic relationships of 54 Phyllium specimens. Tree is rooted with Cryptophyllium as the outgroup. Support values are shown at each node (SH-aLRT / UFBoot). The asterisk (*) indicates maximum support (100). Newly added specimens are shown in green text and new species are highlighted in green. The blue stripes on internal branches mark dispersal to Indonesia, with blue boxes specifying the exact island or region. Abbreviations: HT, holotype; PT, paratype.

Figure 2. Distribution map for all Phyllium species used in the molecular analysis as well as the newly described species from Obi Island not represented in the phylogenetic tree. Species names of Phyllium from Malaysia, the Philippine Islands, and New Britain (Papua New Guinea) are shown in gray. The Indonesian archipelagic state is highlighted in blue and symbols of sampling sites of Indonesian Phyllium species are in dark blue. White symbols show the location of the remaining Phyllium from Malaysia, the Philippine Islands and New Britain (Papua New Guinea). The inset presents an enlarged section of Sabah (Malaysia: Borneo) and the six species found there. Abbreviations: Hal, Halmahera; Jav, Java; Kal, Kalimantan; NG, New Guinea (Papua); Ser, Seram; Sul, Sulawesi; Sum, Sumatra.

Figure 6. Phyllium cayabyabi sp. nov. holotype female, # 20-135 (IMQC). A. Details of antenna, head, thorax, and front leg, dorsal; B. Habitus, ventral; C. Thorax, lateral (head to the left); D. Habitus, dorsal; E. Details of mesonotum, dorsal; F. Terminalia, ventral (note that the subgenital plate has been cut in half when it was gutted and dried); G. Terminalia, dorsal. Scale bar: 30.0 mm (B, D).

Figure 7. Phyllium cayabyabi sp. nov. paratype male, # 20-137 (Coll RC). A. Details of antenna and head, dorsal; B. Habitus, dorsal; C. Habitus, ventral; D. Details of pronotum and mesonotum, dorsal; E. Terminalia, ventral; F. Thorax, lateral (head to the left). Scale bar: 20.0 mm (B, C).

Figure 8. Phyllium cayabyabi sp. nov. paratype egg (Coll RC # 20-138). A. Dorsal view; B. Lateral view (dorsum to the left); C. Ventral view; D. Opercular (anterior) view; E. Posterior view. Scale bar: 3.0 mm (A – E).

Figure 9. Phyllium cayabyabi sp. nov. paratype egg (Coll RC # 20-140). Scanning electron micrographs of the egg. A Overview of the egg, lateral view. B – E. Details of the egg surface structures; B. Spatulate pinnae; C. Spatulate tip with glue; D. Hollow columnar pinnae; E. Cross-sections of removed pinnae showing fibrillar infill. Abbreviations: gl, glue residuals. Scale bars: 1 mm (A), 100 µm (B – E).

Figure 10. Phyllium cayabyabi sp. nov. holotype female antenna and fine details (Coll RC # 20-135). Scanning electron micrographs of female antenna. A. Overview of the antenna, medial view; B. Third antennomere; C. Stridulatory ridge; D. Stridulatory file. Scale bars: 500 µm (A), 300 µm (B), 30 µm (B).