Pterinoxylus cocoense, Hennemann & Conle & Valero & Nishida, 2022

Hennemann, Frank H., Conle, Oskar V., Valero, Pablo & Nishida, Kenji, 2022, Studies on Neotropical Phasmatodea XXV: Revision of Pterinoxylus Serville, 1838, with the descriptions of two new species from Costa Rica. (Phasmatodea: Oriophasmata: Cladomorphinae: Pterinoxylini), Zootaxa 5208 (1), pp. 1-72 : 9-15

Pterinoxylus cocoense n. sp.

Figs. 2–3 , 21A , 29C–D , 30A–B , 31

HT, ♀: Costa Rica, Prov. Puntarenas, P.N. Isla del Coco, Bahía Chatan , 1–100m, Oct 1994, J. F. Quesada, Long: -87:03:20_ Lat: 5:32:40 #47945; Costa Rica MNCR-A CRI002 575708; Especímens en Atta A. Lépiz 16.4.2008 [ MNCR-A] .

PT, ♀, + 1 egg (ex ovipositor): Costa Rica, Prov. Puntarenas, P.N. Isla del Coco, Bahía Chatan , 1–100m, Oct 1994, J. F. Quesada, Long: -87:03:20_ Lat: 5:32:40 #47945; Costa Rica MNCR-A CRI002 575707 [ MNCR-A] .

PT, ♀: Costa Rica, Prov. Puntarenas, Puntarenas, P. N. Isla del Coco, Bahía Wafer , 0–100m, 06 JUN 2013, J. A. Azofeifa, Colecta Libre, -87:03:30 05:32:40, #107147 [ MNCR-A] .

PT, ♂: Costa Rica, Prov. Puntarenas, Puntarenas, P. N. Isla del Coco, Bahía Wafer , 0–100m, 16 ABR 2013, J. A. Azofeifa, C. Víquez, Colecta Libre, -87:03:30 05:32:40, #107146[ MNCR-A] .

PT, ♂: Bahía Chatan , P.N. Isla del Coco, Prov. Punt., Costa Rica, 5 a 9 feb 1993, F. A. Quesada, L–S–0, 0; Costa Rica MNCR –A CRI001 851974 [MNCR-A].

PT, 2 ♂♂: Costa Rica, Prov. Puntarenas, P.N. Isla del Coco, Cerro Yglesias , 600m, 16 21 MAR 2002 , R . Hernandez, malaise, Long:87:04:47 Lat : 05:31:32, #67306 [ MNCR-A] .

PT, 2 ♂♂ (penultimate instar), 1 nymph n4, 1 nymph n3, 1 nymph n2: Costa Rica, Prov. Puntarenas, Isla del Cioco, Bahía Yglesias , A la Catarata Yglesias por el Sendero, 20m, 21 DIC 1997, F. Ulate, C. Flores, Long: 87:04:12_ Lat: 5:31:06, #49467 [ MNCR-A] .

Diagnosis: This new species differs from all other representatives of the genus by the small size and comparatively shorter alae of both sexes, which do not reach the posterior margin of the median segment in ♀♀ and hardly project over posterior margin of abdominal tergum IV in ♂♂. Females resemble those of P. spinulosus Redtenbacher, 1908 , but in addition to the features mentioned differ by the relatively longer, slenderer legs and considerably less lamellate, just weakly undulate carinae of the fore legs. Males are readily distinguished from all other species in the genus by the flattened and unarmed head, weakly and very sparsely tuberculose mesonotum as well as the slender legs that are destitute of enlarged teeth or lobes. The eggs differ from all other known eggs of the genus by their smaller dimensions as well as the densely tuberculose and rugulose capsule surface.

Etymology: Named after the type-locality Isla del Coco (Cocos Island), a small oceanic island some 550 km off the Costa Rican Pacific coast and a World Heritage Site.

Description: ♀♀ ( Fig. 2 ). The smallest representative of the genus (body length including subgenital plate 103.0–140.0 mm), form twig –like and fairly slender with the body surface partly, variably and unevenly sculptured, short alae (length 9.5–11.0 mm) and a moderately long subgenital plate. Colouration variably greyish mid to dark brown and sometimes with a slight greenish wash; mostly almost plain but may be faintly and irregularly flecked with paler brown. The legs often with irregular dull green mottling. Frons with two washed black markings.Antennae dark greyish brown and somewhat darker ventrally, the terminal segment cream. Tegmina and costal region of alae roughly of same colour as body and sometimes with very faint mottling; the basal portion of costal region of alae that is covered by the tegmina dull red and dull red ventrally. Anal region of alae slightly transparent grey with all anal veins boldly marked with black ( Fig. 2A ). Lobes and excrescences of the head, body and extremities may be green ( Figs. 29C–D , 30A–B )

Head: Ovoid and oval in cross-section, about 1.6x longer than wide. Between the eyes with a low transverse swelling, that is indented medially. Vertex very gently rounded with a distinct, impressed coronal fissure, surface unevenly tuberculose; in centre with a pair of somewhat enlarged obtuse swellings and a further pair of enlarged tubercles at posterior margin; the central pair of swellings may be strongly enlarged to form large , very irregularly crenulate auriform lobes ( Fig. 29D ), the tubercles nearby strongly enlarged and spiniform and the posterior pair of tubercles represented as short spines ( Fig. 2E ). Genae with a longitudinal row of 3–4 nodes. Eyes almost circular in outline and their diameter contained about 2x in that of genae; strongly projecting. Antennae almost reaching tip of protarsi and laid back somewhat projecting over posterior margin of metanotum; consisting of about 32 antennomeres. Scapus flattened dorsoventrally, narrowed basally, strongly deflexed laterally and with lateral margins distinctly rounded. Pedicellus subcylindrical and almost two-thirds the length of scapus. Third antennomere slightly longer but considerably narrower than pedicellus.

Thorax: Pronotum longer and but slightly narrower than head, sub-rectangular with the lateral margins gently concave; transverse median sulcus short, C-shaped, moderately distinct and almost lateral margins of segment. Median line slightly impressed over entire length of segment and the surface unevenly set with several granules and small tubercles; four somewhat enlarged tubercles on anterior margin and occasionally one or two pairs of enlarged and obtusely spiniform tubercles near posterior margin ( Fig. 2E ). Sometimes also a somewhat enlarged obtuse lateral tubercle in anterior portion and two such tubercles at lateral margin in posterior portion. Mesothorax moderately long and slender, about 3.3x the length of pronotum and gently narrowed anteriorly. Mesonotum with a distinct but irregularly shaped longitudinal median carina, surface texturing very variable and unevenly rugulose and/or tuberculose; sometimes set with several rugulose and irregularly crenulate swelling of variable sizes (paratype with collection number 575708, Fig. 2E ). Mesopleurae unevenly rugulose and more or less distinctly but sparsely tuberculose; metapleurae set with several ± spiniform tubercles. Sensory areas at lateral margins of prosternum weakly developed and indistinct; the central sensory area of probasitsternum large and anteriorly expanding over entire width of notum. Meso- and metasternum irregularly rugulose and granulose ( Fig. 2D ); the rugulae most distinct and numerous in anterior portion of mesosternum and some of the rugulae raised to form node-like structures (sculpturing less pronounced on metasternum). Tegmina sub-oval, narrowed basally scale–like and rather flattened; notably projecting over posterior margin of metanotum. Alae short and just not reaching to posterior margin of median segment.

Abdomen: Median segment about 1.6x longer than metanotum and about equal in length to abdominal segment II; almost 1.6x longer than wide, smooth and with lateral margins gently concave. Segments II–IV slightly increasing, V–VII decreasing in length; II and III somewhat widening IV–VII very slightly gradually narrowing, sub-rectangular in shape and on average 1.4–1.5x longer than wide. Tergum VII with lateral margins in posterior half deflexed to form a prominent, bluntly angular but irregularly shaped lobe, which may extend laterally by as much as two-thirds of the body width. Complete surface of all terga unevenly rugulose and granulose; all with a closely placed pair of fine but irregular longitudinal carinae that vary in emphasis and usually terminate in a nodule, small swelling or spiniform, laterally compressed process posteriorly on each tergum. The rugulae forming a further irregular sinuate lateral carina, which posteriorly may terminate in a more or less distinct, sometimes crenulate to foliaceous or bi- to trifid lobe on II and V; the size and shape of these lobes very variable. Lateral margins of II–VI sometimes with 2–3 irregular small lobes posteriorly (paratype with collection number 575708). Sterna II–VII unevenly granulose and with a pair of short rugulae near posterior margin. Sternum VII with two very prominent irregularly shaped and obtuse longitudinal carinae; praeopercular organ formed by two small conspicuously node-like posteromedian tubercles. Terga VIII and IX with a small, irregularly foliaceous posterolateral lobe; VIII constricted medially and about three-quarters the length of VII, IX shorter and rectangular.Anal segment somewhat shorter than IX with lateral margins somewhat deflexed and widening towards the posterior; the posterior portion narrowed and the posterior margin with a deep, angular median excavation and the outer portions irregularly rounded. Epiproct small shield-shaped and very slightly extending beyond posterior margin of anal segment; with an acute longitudinal median carina dorsally. Cerci very small, compressed laterally, tapered towards the tip and just reaching to posterior margin of anal segment. Subgenital plate variable in length (compare Figs. 2F and 2G ) and shape and extending over apex of abdomen by at least the length of the two terminal terga combined; carinate longitudinally, narrowly scaphiform with the lateral margins ± sub-parallel in dorsal aspect and the apex ± triangular ( Figs. 2H–I ).

Legs: All moderately short but slender for the genus; profemora a little more than three-quarters and mesofemora about two-thirds the length of mesothrax, hind legs reaching about half way along abdominal segment VII. Anterodorsal carina of profemora strongly raised, deflexed and unevenly undulate; occasionally a few small lobules present on posterodorsal carina. Posteroventral carina just slightly dilated with margin wavy and with a few tooth-like nodes in compressed basal portion of femur. Both dorsal carinae of protibiae unevenly deflexed and with several rounded du bluntly angular lobes; the posteroventral carina prominently dilated, lamellate irregularly undulate and slightly gradually lowering towards apex of tibia. Posterodorsal carina of mesofemora with a large and broad, semi-circular to apically toothed sub-apical lobe and several unevenly shaped and sized much smaller lobes to triangular and tooth-like expansions in the basal two-thirds; armature of anterordorsal carina similar but less pronounced. Antero- and posteroventral carinae supplied with a prominent and obtusely triangular tooth-like expansion pre-apically and a somewhat smaller tooth-like expansion post-medially, otherwise with about four smaller teeth, two in the basal portion, one between the two larger expansions and one close to apex of femur. Armature of metafemora principally similar but less pronounced. The medioventral carina of meso- and metafemora fairly distinct and supplied with obtuse granules. Ventral carinae of meso– and metatibiae smooth and just very weakly wavy; the anterodorsal carina with a closely placed pair of rounded to triangular and tooth-like lobes subbasally a fairly prominent expansion sub-apically and about 3–4 smaller teeth in between. Probasitarsus with dorsal carina distinctly raised and forming a roundly triangular lobe; second tarsomere with a similar but much smaller dorsal lobe. Meso- and metabasitarsus hardly longer than following tarsomere and with the dorsal carina just gently raised and rounded.

♂♂ ( Fig. 3 ). Smallest representative of the genus (body length 79.5–82.5 mm), form stick –like and fairly stocky for the genus, with comparatively short alae (length 29.0– 29.5 mm), just very weakly and indistinctly tuberculose mesothorax and unarmed legs. General colouration ranging from fairly plain drab or ochre to yellowish mid brown. The largest cephalad and thoracic tubercles tipped with pale cream. Tegmina of same colour as body and often with anterior margin broadly white except for the very basal portion. Costal region of alae with a reddish hue and dull red ventrally, the anterior margin broadly marked with white in the basal one-thirds. Anal region transparent greyish brown with several variably sized transparent patches; all anal veins dark brown with interruptions at the transparent patches ( Figs. 3A–C ). Antennae dull ochre to mid brown dorsally and in the median portion dark brown to black ventrally; the terminal antennomere dull cream.

Head: Shape generally as in ♀♀, central portion of vertex more flattened and eyes much more prominent and projecting hemispherically from head capsule, their diameter contained only 1.6x in length of genae. Vertex just sparsely supplied with low granules and small nodules, the genae with a longitudinal row of 3–4 small nodules. Antennae long and slightly projecting over posterior margin of abdominal segment II, with 31–32 segments. Scapus less prominently dilated than in ♀♀.

Thorax: Pronotum as in ♀♀ and notably longer than head, sparsely supplied with scattered low granules and nodules; usually one pair of somewhat more pronounced nodes near posterior margin. Mesothorax elongate, slender and 3.7x longer than pronotum; complete surface densely but unevenly granulose. Mesonotum with a faint longitudinal median carina, that becomes increasingly obsolete behind the mid of segment; surface otherwise set with a few low and obtuse paired tubercles in anterior half and 5–7 nodes along lateral margins in anterior half of segment. Meso- and metapleurae granulose and with a few small nodes. Meso- and metasternum set with a few scattered nodes and some longitudinally directed rugulae ( Fig. 3C ). Tegmina roughly oval on outline, slightly projecting over posterior margin of metanotum and with a very indistinct, weakly rounded central hump. Alae reaching about one third along abdominal tergum V.

Abdomen: Median segment 1.25x longer than metanotum, almost 2.6x longer than wide and smooth. Segment II very slightly longer than median segment, II–IV roughly equal in length, V–VII very slightly decreasing in length; II–IV about 2.4x, VII only 2.2x longer than wide. II–VI parallel-sided and of uniform width, VII a little narrowed. Terga II–IX with a pair of closely placed fine longitudinal median carinae, that are faint on II–IV but become increasingly pronounced on the following terga; surface otherwise very weakly rugulose und granulose; V–IX with a further somewhat more pronounced lateral carina. All sterna weakly rugulose and sparsely granulose; the rugulae roughly forming two irregular longitudinal carinae in posterior portion of each sternum. Tergum VIII a little more than three-quarters the length of VII and somewhat widening towards the posterior. IX three-quarters the length of VIII, about 1.2x longer than wide and rectangular. Anal segment three-quarters the length of IX, sub–rectangular in dorsal aspect, slightly narrowed at anterior margin and very gently widening towards the posterior; the posterior margin with a shallow median indention and the outer portions broadly and weakly rounded ( Fig. 3E ); ventral surface of outer portions of posterior margins armed with a few small denticles. Epiproct very small, transverse and fully hidden under anal segment. Cerci small, moderately compressed laterally, oval in cross-section and the apex very slightly club-shaped; somewhat projecting beyond posterior margin of anal segment ( Fig. 3D–E ). Vomer broad and roundly triangular in shape with the lateral margins gently rounded, the ventral surface almost flat and the short terminal hook strongly upcurved ( Fig. 20A ). Poculum strongly convex with a bluntly conical central hump and slightly projecting over posterior margin of tergum IX ( Fig. 3D ); the posterior half carinate longitudinally and the posterior margin narrowly bi–lobed with a deep median incision ( Fig. 3F ).

Legs: Relatively longer and slenderer than in ♀♀ and destitute of armature with the exception of two small and flat sub-apical teeth on two outer ventral carinae of meso- and metafemora. Profemora roughly equal in length to mesothorax, mesofemora four-fifths the length of mesothorax and hind legs reaching to posterior margin of abdominal segment VII. Anterodorsal of profemora and protibiae very slightly deflexed with margin weakly wavy. Medioventral carina of meso- and metafemora well pronounced and supplied with small granules. Probasitarsus elongate, slightly longer than following two tarsomeres combined and with dorsal carina gradually raising towards the apex. Meso- and metabasitarsus almost as long as following two tarsomeres combined, slender.

Variability: As for the other species in the genus, the three available ♀♀ show there is considerable variability relating to several morphological characters. In general, all the body and leg sculpturing and armature is much more pronounced in the paratype with collection number 575708 ( Figs. 2B–D ) and live ♀ observed by Juan G. Abarca Alvarado ( Figs. 29C–D , 30A–B ) than in the other two specimens. The latter ♀ for instance has the cephalic horns noticeably larger and forming two auriform lobes ( Fig. 2E ), whereas these are only represented by a pair of blunt tubercles in the holotype and second paratype. Furthermore, in this specimen some of the mesonotal tubercles are bi- or trifid, the posterior pair of projections on abdominal terga II–V form multi-dentate lobes and all the lobes of the legs are much more foliaceous. The ♂♂ at hand are much more consistent morphologically and do not exhibit any noteworthy variability.

Eggs ( Fig. 3G ): Only one egg is available, which unfortunately is damaged and lacks the operculum. Thus, only a brief description is provided here.

Small for the genus. Capsule moderately elongate, ovoid, sub-circular in cross-section and with the dorsal surface more convex than ventral surface. Entire capsule surface strongly tuberculose and rugulose, the rugulae forming a blunt keel that in some distance surrounds the micropylar plate. A very broad and blunt longitudinal bulge running from the micropylar plate to the polar area; laterally accompanied by a tuberculose ridge. Peripheral polar excrescence very short. Micropylar plate just slightly longer than wide with anterior end fairly blunt. General colour reddish mid to dark brown, the micropylar plate blackish brown. Measurements [mm]: Length 5.4, width 2.4, height 2.6, length of micropylar plate 1.4.

Comments: This new species is the smallest known representative of the genus. It is the so far only known stick insect from the Isla del Coco (Cocos Island) and hence of great interest geographically. Cocos Island lacks permanent inhabitants and is positioned about 550 km southwest of the Costa Rican mainland in the Pacific Ocean. It is almost rectangular in shape, measuring only about 8 x 3 km and having an area of approximately 23,85km 2. Most of the area is covered in rainforest and after becoming a Costa Rican National Park in 1978 the island was designated a World Heritage Site by UNESCO in 1997.

A life ♀ was observed by Juan G. Abarca Alvarado ( Universidad Nacional , Costa Rica) on April 14 th 2022 in the cloud forest close to Cerro Pelón at an altitude of 560 metres ( Figs. 29C–D , 30A–B ). The specimen was found about one metre off the ground during the day among vegetation mainly consisting of ferns and grasses ( Fig. 30B ) .

Distribution ( Fig. 31 ): Costa Rica (Prov. Puntarenas, Isla del Coco). Endemic.

Figures

FIGURE 2: Pterinoxylus cocoense n. sp. ♀♀. A. HT, dorsolateral view [MNCR-A]; B. PT, dorsolateral view [MNCR-A, collection no. 575708]; C. PT, lateral view [MNCR-A, collection no. 575708]; D. PT, ventral view [MNCR-A, collection no. 575708]; E. Head, pro and mesonotum of PT in dorsal view [MNCR-A, collection no. 575708]; F. Apex of abdomen of HT in lateral view [MNCR-A]; G. Apex of abdomen of PT in lateral view [MNCR-A, collection no. 575708]; H. Apex of abdomen of HT in dorsal view [MNCR-A]; I. Apex of abdomen of HT in ventral view [MNCR-A].

FIGURE 3: Pterinoxylus cocoense n. sp. ♂ PT [MNCR-A, collection no. #107146] and egg. A. PT, dorsolateral view; B. PT, dorsal view; C. PT, ventral view; D. Apex of abdomen of PT in lateral view; E. Apex of abdomen of PT in dorsal view; F. Apex of abdomen of PT in ventral view; G. Egg in dorsolateral view, PT (operculum lacking).

FIGURE 20: Pterinoxylus spp. venation of alae. A. P. speciosus n. sp. ♀ HT, dorsal view (mirrored horizontally) [MNCR-A, collection no. 042809]; B. P. spinulosus Redtenbacher, 1908 ♀, ventral view with tympanal area coloured yellow [coll. OC]; C. P. speciosus n. sp. ♂ PT, dorsal view (mirrored horizontally) [MNCR-A, collection no. 52571]. Explanation of abbreviations: 1AA-7AA = first–seventh anterior anal; 1PA-7PA = first–seventh posterior anal, C = costa, Cu = cubitus, Cu1 cubitus 1, Cu2 = cubitus 2, E = empusal, M = media, MA = media anterior, Mp1 = media posterior 1, Mp2 = media posterior 2, R = radial, R1 = radius 1, Rs = radial sector, Sc = subcostal, TA = tympanal area.

FIGURE 21: Pterinoxylus spp. terminal two abdominal segments of ♂♂ in ventral aspect, showing vomer and poculum. A. P. cocoense n. sp.: PT [MNCR–A, collection no. #107146]; B. P. crassus (Kirby, 1889): Specimen from Martinique [coll. FH, No. 0588–21]; C. P. eucnemis (Burmeister, 1838): Specimen from French Guiana [coll. OC]; D. P. perarmatus (Redtenbacher, 1908): Specimen from Osa Peninsula, Costa Rica [coll. FH, No. 0841–6]; E. P. speciosus n. sp.: PT [MNCR–A, collection no. 52571]; F. P. spinulosus Redtenbacher, 1908: Specimen from Greenhills, Belize [coll. OC]. Scale = 1 mm.

FIGURE 29: Live insects.A. P. eucnemis (Burmeister, 1838), ♀ at Réserve Naturelle Nationale de la Trinité, French Guiana (© Philippe Lelong); B. Same specimen as in A, closeup of head and prothorax in dorsal view (© Philippe Lelong); C. P. cocoense n. sp., ♀ at Cerro Pelón, Isla de Coco (© Juan G. Abarca Alvarado); D. Same specimen as in C, closeup of head and prothorax in dorsal view (© Juan G. Abarca Alvarado).

FIGURE 30: A. P. cocoense n. sp., ♀ at Cerro Pelón, Isla del Coco showing camouflage on a mossy stem in its natural habitat (© Juan G. Abarca Alvarado); B. Habitat of P. cocoense n. sp. at Cerro Pelón, Isla del Coco (© Juan G. Abarca Alvarado).

FIGURE 31: Map showing the known records for Pterinoxylus cocoense n. sp., P. crassus Kirby, 1889 and P. perarmatus (Redtenbacher, 1908). The imprecise locality „Guatemala“ for a specimen of P. perarmatus in the collection of MHNG is omitted.