Orphnaecus mimbilisanensis Sumogat, Acuña et Nuñeza, 2025

Sumogat, J. J., Acuña, D. C. & Nuñeza, O. M., 2025, A new tarantula species of the genus Orphnaecus Simon, 1892 (Araneae: Theraphosidae) from Mindanao Island, Philippines, Far Eastern Entomologist 522, pp. 8-21 : 12-19

Orphnaecus mimbilisanensis Sumogat, Acuña et Nuñeza , sp. n.

https://zoobank.org/NomenclaturalActs/ BF3CE96F-C671-48BA-B0E4-70B073E0B066

Figs 2–9

TYPE MATERIAL. Holotype: ♂ PNM-18876 (field# MPL02 ), Philippines: Mindanao Island, Misamis Oriental, Municipality of Balingoan, Brgy. Mapua, Mimbilisan Protected Landscape , 470 m a.s.l., 1–8 April 2023, JJ Sumogat leg. Paratypes: 3 ♀, UST-ARC 0230 (field# MPL01 ), NSM-2449 (field# MPL04 ), PNM-18878 (field# MPL03 ), same data as for the holotype; 1 ♂, PNM-18877 (field# MPL07 ), same data as for the holotype, 14 January 2025; NSM-MSUIIT/ PNM / UST-ARC .

New species is placed to the genus Orphnaecus in having a reniform lyra on the prolateral maxilla with a row of large club-shaped stridulatory setae (bacillae) ( Fig. 5B ), in having a palpal organ in males with stout lanceolate embolus having a pronounced basal lobe and long PS keel from tip to base ( Fig. 5C–E ), in the presence of dense scale brush on palpal patella of males ( Fig. 5A ), and in having spermathecae converging and mesoprolaterally concave. O. mimbilisanensis sp. n. can distinguished from all other known congeners ( Orphnaecus sensu stricto) in having a relatively higher carapace with CH is around 1/2 of CL (congeners have CH around 1/3 of the CL), in having longer leg 1 than leg 4 in males, and in having relatively longer palpal organ with length 3/5 of palpal tibia in males (congeners have palpal organ length with 2/5 of the palpal tibia). This species further differs from O. kwebaburdeos in having a spermathecae being narrow and concave on both sides laterally, and in having shorter leg 1 than leg 4 in females. It also differs from O. pellitus in not exhibiting troglomorphism. O. mimbilisanensis sp. n. is currently the only known species in mainland Mindanao.

REMARKS. The females of O. mimbilisanensis sp. n. cannot be distinguished from O. adamsoni. Based on our examination of the paratype female (PNM 14888) of O. adamsoni, the same specimen described in Salamanes et al. (2022), this specimen was misidentified and misplaced in Orphnaecus , due to the presence of a plumose setal field on retrolateral chelicerae, rows of thorn stridulatory setae on the prolateral maxilla, conspicuous white bands on leg segments, and stripe patterns on the dorsal abdomen, which characters are absent in Selenocosmiinae but synapomorphy to Ornithoctoninae ( Acuña et al., 2025). Description of female O. adamsoni from other paratypes is necessary.

DESCRIPTION. Holotype male, PNM-18876, (field#MPL02): TL 55.48.

Prosoma ( Figs 3 , 4 ). Carapace ( Fig. 3A ), CL 15.95, CW 13.75, CH 7.2, longer than wide, oblong, integument light to dark brown, densely covered with short metallic gray to white scales, and with four pairs of dorsal weak furrows. Cephalic area larger than thoracic. Fovea ( Fig. 3E ) slightly procurved, 2.26 width, 2.32 curve length, 150.46° curvature, slightly narrower than ocular tubercle width. Ocular tubercle ( Fig. 3D ) 2.00 long. 2.74 wide, transversely oblong; clypeus 0.42. Anterior eye row slightly procurved, posterior eye row recurved. Eye diameters: ALE 0.69> AME 0.66> PME 0.57> PLE 0.48. Interocular distances: ALE-ALE 1.41, ALE-AME 0.10, ALE-PLE 0.14, ALE-PME 0.18, AME-AME 0.27, AME-PLE 0.50, AME-PME 0.11, PLE-PLE 1.9, PLE-PME 0.13, PME-PME 1.17. AME circular, PME ovoid, PLE and ALE oblong. Rows of short tactile setae present longitudinally across OT dorsally from clypeus. Chelicerae ( Fig. 4 ) with light brown paturon, darker dorsally, with prominent tactile setae and grayish-white scales, dorsally, and with amber-colored fang. Paturon 8.43 long, 5.29 high. Fang curved length 5.97. Teeth 12 ( Fig. 4B ), parallel to long brown-orange oral fringe and36 mesoventral denticles ( Fig. 4C , arrow). Cheliceral strikers ( Fig. 4F ) ~67 (primary to secondary rows) in 3 or 4 horizontal rows, needle-form to spiniform, primary rows with filiform ends, tertiary rows very short needleform. Ventral prosoma integument yellowish-amber. Sternum longer than wide, covered with dark tactile setae and gray scales, 6.92 long, 6.96 wide, with three pairs of sternal sigilla and a pair of labiosternal sigillum, anterior sternal sigilla inconspicuous, posterior sigilla prominent. Labium yellow-amber, 2.16 long, 3.21 wide, with ~492 cuspules. Maxillae ( Fig. 5B ) 4.83 long, 2.88 wide, with ~339 cuspules, yellow-amber ventrally, dark brown dorsolaterally, covered with brown tactile setae. Maxillary lyra ( Fig. 5B ) in a reniform patch, broader proximally, surrounded by fine pallid setae, and composed of ~462 short spiniform setae and a row of large 8 clavate rods increasing from 0.26 to 0.65 (proximal to distal).

Opisthosoma. Abdomen, 18.46 long, 11.67 wide, 10.14 high, oblong, dark brown to black integument, covered with long tactile setae dorsally, shorter ventrally, and covered with light brown scales which reflect deep purplish-blue sheen. PLS (6.33) slightly longer than PMS.

Genitalia ( Fig. 5A, C–E ). Palpal organ: tegulum 1.79 wide, bulbous, golden-brown to amber. Embolus 2.32 long, 0.85 wide basally, dark, lanceolate, moderately long, and slender with long PS emerged from tip to base, with short PI at around apical 1/5, with A keel emerging at the tip, and StR and BL pronounced.

Legs. RF = 100.61%, leg formula: 1423. Leg and pedipalp lengths, see Table 1. Legs robust, long, covered with thin short and long light to dark tactile setae. Pedipalp ( Fig. 5A ) integument dark yellow-amber, covered with moderately long gray setae from femur to patella, longer, thinner setae on tibia. Palpal patella with dense long grayish scales, dorsally ( Fig. 5A , arrow). Leg femur to patella moderately covered with short light black tactile setae, tibia to tarsus densely covered with long thin tactile setae. Dorsal side has two rows of trichobothria, interspersed with spines on the metatarsus of all legs. Ventral metatarsi 3 and 4 have rows of spines. Femora robust, with femur 1 longest and femur 3 shortest. Scopulae of legs 4 and 3 divided by rows of spines, legs 1 and 2 undivided. Metatarsal spines present on legs 3 and 4 dorsally, and on all legs ventrally. Tarsi 1 – 4 with pair of claws, tarsus 4 with third inferior claw.

Paratype female, PNM-18878 (field# MPL03 ): TL 41.46 .

Prosoma ( Figs 7 , 8 ). Carapace ( Fig. 7A ), CL 17.11, CW 14.11, CH 9.7, longer than wide, larger than opisthosoma, recurved near pedicel, reddish brown to dark brown, covered with moderately dense gray scales and dark setae, and with four pairs of weak furrows. Fovea ( Fig. 7E ) 2.43 curve length, 2.43 width, 133.94° curvature, procurved. Ocular tubercle ( Fig. 7D ) 1.97 long, 2.82 wide, wider than fovea, transversely oblong; clypeus 0.58. Anterior eye row slightly procurved, posterior eye row recurved. Eye sizes: ALE 0.75> AME 0.67> PME 0.57> PLE 0.53. Inter-eye distances: ALE-ALE 1.56, ALE-AME 0.23, ALE-PLE 0.42, ALE-PME 0.39, AME-AME 0.29, AME-PLE 0.66, AME-PME 0.12, PLE-PLE 2.07, PLE-PME 0.19, PME-PME 1.19. AME circular, PME ovoid, PLE and ALE oblong. Rows of short dark setae cover from posterior surface of OT to clypeus, medially ( Fig. 7D ). Chelicerae ( Fig. 8 ) 10.18 long, 7.29 high, with dark brown paturon, dense brown setae dorsally, smooth retrolaterally. Fang dark brown with crimson hint, 7.46 c. Row of 12 promarginal teeth ( Fig. 8B ) parallel to rows of brown-orange oral fringe and 66 mesoventral denticles ( Fig. 8C , arrow). Cheliceral strikers ( Fig. 8F ) ~65 (primary to secondary rows) in 3 or 4 horizontal rows, needle-form to spiniform, primary rows with filiform ends, tertiary rows very short needleform. Ventral prosoma integument reddish brown to dark brown ( Fig. 7B ). Sternum ( Fig. 7B ) 7.70 long, 7.47 wide, covered with dense short black setae and grayish brown scales, with three pairs of sternal sigilla and a pair of labiosternal sigillum, anterior sternal sigilla inconspicuous, posterior sigilla prominent. Labium ( Fig. 7F ) amber-brown, 2.42 length, 3.28 width, with ~584 cuspules. Maxillae, 6.44 length, 3.31 width, with ~221 cuspules, brown-amber ventromedial, dark brown dorsolaterally, covered with brown tactile setae. Maxillary lyra ( Fig. 9B ) with ~296 short spiniform setae and 16 clavate spines, length ranging from 0.30–1.09. Lyrate setae form a reniform patch, with dark brown tips and red stalks, surrounded by pallid fine setae.

Opisthosoma. Abdomen 16.98 length, 10.16 width, 8.98 height, oblong, dark brown to black, covered with long tactile setae and light brown scales that reflect purplish-blue sheen, with pronounced epigastric furrow, and book lungs light yellow. PLS 6.10 length, PMS 2.61 length, both projecting posteriorly.

Genitalia ( Fig. 9A ). Spermatheca 1.47 long, both receptacles 2.47 wide, median gap 0.63, left receptacle apically 0.56 wide, medially 0.49 wide, basally 0.76 wide. Spermatheca unilobed, narrow, slightly similar to O. pellitus in shape but broader apically, in peanut-like shape, converging or apically narrower than the base, mesolaterally concave on both sides and slightly pointing inwards. Covered with translucent sheath and with translucent uterus externus, similar to bursa copulatrix.

Legs (left side). RF 98.66%, leg formula: 4123. Leg and pedipalp lengths (see Table 2). Pedipalp integument dark brown, covered with moderately long brown tactile setae from femur to tarsus, and with rows of trichobothria in the tarsus, dorsally. Legs robust and long, covered with intermixed thin short and long dark tactile setae. Leg 4 longest, leg 3 shortest. Each leg has two tarsal claws, tarsus 4 with a third inferior claw. Trichobothria present on all tarsi, dorsally. Metatarsal spines are present on legs 3 and 4, dorsally, and on all legs, ventrally. Scopulae of legs 4 and 3 divided, legs 1 and 2 undivided.

ECOLOGY. The habitat of O. mimbilisanensis sp. n. in MPL features an undulating slope ranging from 35° to 40°. The area experiences significant shading due to the abundance of canopy and dipterocarp trees. Predominantly, the lauan tree ( Shorea spp. ) stands out as the emergent tree species. Within the canopy layer, red lauan ( Shorea negrosensis Foxw. ) and white lauan ( Shorea contorta S.Vidal ) are the dominant tree species, with height of 20 to 35 m. The lower vegetation layer comprises palm species, sedges, and aroids, while a diverse range of fern species envelop the ground. Both rocky surfaces and decomposing logs display abundant moss varieties, while a layer of leaf litter, approximately 4 cm in thickness, conceals the clay-rich soil. The collection area was an abandoned agricultural land with the cultivation of coffee, coconut palms, and fruit-bearing trees. All activities ceased due to the prohibition from the Department of Environment and Natural Resources and the local government. However, the area still experiences minor disturbances due to few illegal intrusions and the clearing activities intended for conservation enhancement. The collected specimens were dwelling in mounds of coconut husks, found in an area with an elevation of 470 m a.s.l. The nests are shallow, approximately 2 inches deep, and 5 inches wide, and were built under or between coconut husks and shells. Their microhabitat is moderately damp, and not in direct sunlight. They cohabitated with ants, scorpions, forest lizards, and small frogs. O. mimbilisanensis sp. n. is referred to as “ duplak ” by the locals.

DISTRIBUTION. Known only from Mimbilisan Protected Landscape in Misamis Oriental, Mindanao Island, Philippines.

ETYMOLOGY. The specific epithet is a Latin adjective derived from the Mimbilisan Protected Landscape, where this species is found.

Figures

Fig. 2. Orphnaecus mimbilisanensis sp. n., holotype male (MPL02) habitus in life, ex situ. A – habitus, dorsal view, before maturity and ultimate molt; B, C – burrow laid with a silk mat and with the entrance covered with silk curtain.

Fig. 3. Orphnaecus mimbilisanensis sp. nov. prosoma. A – carapace, dorsal view; B – prosoma, ventral view; C – prosoma, lateral view; D – ocular tubercle, dorsal view; E – fovea, dorsal view; F – labium with cuspules, ventral view.

Fig. 4. Orphnaecus mimbilisanensis sp. n., holotype male chelicerae. A – chelicerae, ventral view; B – cheliceral teeth, prolateral view; C – mesoventral denticles (red arrow), ventrolateral view; D – paturon and fang, prolateral view; E – paturon and fang, retrolateral view; F – cheliceral strikers, retrolateral view.

Fig. 5. Orphnaecus mimbilisanensis sp. n., holotype male pedipalp, lyra, and palpal organ. A – right pedipalp, retrolateral view, with the dense dorsal scale brush (arrow) on the palpal patella; B – lyra (stridulatory organ) on the left prolateral maxilla surface; C – right palpal organ, retrolateral view; D – right palpal organ, prolateral view; E – right palpal organ, dorsal view. Abbreviations: A – apical keel, BL – basal lobe, PI – prolateral inferior keel, PS – prolateral superior keel, StR – subtegular ridge.

Fig. 6. Orphnaecus mimbilisanensis sp. n., paratype female (MPL03). A – habitus, dorsal view; B, C – female in its burrow under piles of coconut husks.

Fig. 7. Orphnaecus mimbilisanensis sp. n., paratype female (MPL03) prosoma. A – carapace, dorsal view; B – sternum, labium, maxillae, and coxae, ventral view; C – prosoma, lateral view; D – ocular tubercle, ventral view; E – fovea, dorsal view; F – labium with cuspules ventral view. 17

Fig. 8. Orphnaecus mimbilisanensis sp. n., paratype female (MPL03) chelicerae. A – chelicerae, ventral view; B – cheliceral teeth, prolateral view; C – denticles (red arrow) with cheliceral teeth, mesoventral view; D – paturon and fang, prolateral view; E – paturon and fang, retrolateral view; F – cheliceral strikers, retrolateral view.

Fig. 9. Orphnaecus mimbilisanensis sp. nov., paratype female (MPL03) genitalia and lyra. A – spermatheca covered with translucent sheath (red arrow) and with translucent uterus externus, ventral view; B – right maxillary lyra on the prolateral maxilla surface.