Aegus occidentalis Pathomwattananurak & Jiaranaisakul, 2024

Pathomwattananurak, Wuttipon & Jiaranaisakul, Kawin, 2024, A new species of Aegus Macleay, 1819 (Coleoptera: Lucanidae: Lucaninae: Aegini) from Thailand with checklist of the genus species from the country, Zootaxa 5453 (3), pp. 341-358 : 342-347

Aegus occidentalis Pathomwattananurak & Jiaranaisakul , new species

( Figs. 6–10 , 15 , 19 , 23–24 , 31 , 35–36 )

Type locality. Thailand, Ratchaburi Province, Suan Phueng District.

Type material (19♂♂, 7♀♀). Holotype, ♂ ( THNHM): Thailand, Ratchaburi Province, Suan Phueng District , 1010 m a.s.l., 28.XII.2020, K. Jiaranaisakul leg. Paratypes: 1♂ ( THNHM), Thailand, Ratchaburi Province, Suan Phueng District , 1010 m a.s.l., 14.IX.2017, K. Jiaranaisakul leg. ; 1♂, 2♀♀ ( THNHM), Thailand, Ratchaburi Province, Suan Phueng District , 7.XI.2021, K. Jiaranaisakul leg. ; 1♂ ( THNHM), Thailand, Ratchaburi Province, Khao Laem , 13°32’16.5”N 99°12’02.6”E, 980 m a.s.l., 9.VIII.2021, K. Jiaranaisakul leg. ; 1♀ ( THNHM), Thailand, Ratchaburi Province, Khao Laem , 13°32’17.0”N 99°11’52.1”E, 1010 m a.s.l., 10.IV.2022, K. Jiaranaisakul leg. ; 1♂, 1♀ ( ICKPS), Thailand, Ratchaburi Province, Khao Laem , 13°33’05.2”N 99°12’16.3”E, 630 m a.s.l., 12.XI.2022, K. Jiaranaisakul leg. ; 1♂ ( RBMF), Thailand: Ratchaburi Prov., Khao Laem , 13°32’17.0”N 99°11’52.1”E, 1,010 m a.s.l., S. Kamtanom leg. ; 3♂♂, 1♀ ( RBMF), Thailand: Ratchaburi Prov., Khao Laem , 13°32’17.0”N 99°11’52.1”E, 1,010 m a.s.l. 16.X.2023, S. Kamtanom et K. Jiaranaisakul leg. , RIM-I-2023-00142—RIM-I-2023-00145; 3♂♂, 1♀ ( THNHM), Thailand: Ratchaburi Prov., Khao Laem , 13°32’17.0”N 99°11’52.1”E, 1,010 m a.s.l. 16.X.2023, S. Kamtanom et K. Jiaranaisakul leg. ; 3♂♂ ( EQSBG), Thailand: Ratchaburi Prov., Khao Laem , 13°32’17.0”N 99°11’52.1”E, 1,010 m a.s.l. 16.X.2023, S. Kamtanom et K. Jiaranaisakul leg. ; 4♂♂, 1♀ ( WPC), Thailand: Ratchaburi Prov., Khao Laem , 13°32’17.0”N 99°11’52.1”E, 1,010 m a.s.l. 16.X.2023, S. Kamtanom et K. Jiaranaisakul leg. ; 1♂ ( TCC), Thailand, Kanchanaburi Province, Sangkhla Buri District , 6.IX.2011, J. Tunprasert leg.

Additional material examined. Thailand, Kanchanaburi Prov., Thong Pha Phum Dist. , XI. 2023, by Mr. Varawut Varaguttanonda (photographs only) .

Description of the holotype ( Figs. 8 , 23–24 ). TL: 28.4 mm, ML: 5.6 mm, HL: 5.3 mm, PL: 5.6 mm, EL: 12.6 mm, HW: 10.1 mm, PW: 10.3 mm, EW: 9.9 mm.

Body: Color black or reddish-black. Body generally matt. Head: Transverse subrectangular, about 1.8 times wider than long; anterior margin concave with large blunted cephalic protruding hump at middle. Ocular canthus narrow, dividing almost totally the full length of eye; punctures around the eye, extending from preocular margin to posterior of head; postocular margin roundly protruding, slightly pointing forward. Antennal club with 3 antennomeres. Mentum: 2.5 times wider than long; middle of anterior margin strongly concave; anterior edge with setae; surface with large punctures. Mandible: Symmetric, slightly bent up with two inner teeth. Basal tooth large and truncate; median tooth blunted, triangular shaped, shorter than basal tooth, located at basal one-third of mandible. Pronotum: Transverse rectangular, about 1.8 times wider than long. Pronotal surface rather dense with small punctures, with denser and larger punctuations in regions near anterior angles. Anterior angle excised; lateral margin between anterior and lateral angle straight; lateral angle obtuse, margin between lateral and posterior angle concave. Scutellum: Diamond shaped, surface finely punctate. Elytra: Shiny black with bluish shaded color, with seven longitudinal carinae on each elytron; anterior margin with dense and large punctures, while lateral margins densely but finely punctate. Sternum: Reddish-black color. Metasternal and abdominal surface covered with sparse and short setae. Legs: Protibia with 8–11 teeth along outer margin; median of outer margin of meso- and metatibia with 2–4 distinct, small spines and rows of setae; mesotibial apex and metatibia bidentate. Femoral surfaces of all legs with sparse and short setae. Genitalia: Basal piece square shaped with long basal lobe slightly flat in lateral view, ratio of width and length about 0.6. Basal piece 1.8 times longer than paramere, ventral plate of basal piece with hyaline stripe from the apical center. Parameres slender, slightly curved outward; apex with translucent area about half of length. Penis slightly shorter than parameres.

Male paratypes ( Figs. 6–7, 9–10 , 15 , 19 ). TL: 17.7–32.2 mm, similar to the holotype. Larger male with mandible more curved and bent upward, wider head, less punctate pronotum. Mandible of smaller male without a median tooth, cephalic hump smaller or absent in very small specimens, surface of pronotum and head with coarsier and denser punctures.

Female paratypes ( Figs.31 , 35–36 ). TL: 17.7–19.8 mm, ML: 1.6–1.8 mm, HL: 2.5–2.6 mm, PL: 4.5 mm, EL: 10.6–11.0 mm, HW: 4.6–5.2 mm, PW: 7.0– 7.6 mm, EW: 7.6–8.5 mm. Habitus: Color black or reddish-black. Head: Coarsely with rounded punctuations; anterior margin slightly concave; punctures on anterior margin with clear setae. Clypeolabrum bilobed. Ocular canthus straight with rounded posterior angle, dividing almost completely the eye. Mandibles symmetric with a bifurcate inner tooth in the middle. Pronotum: Trapezoidal; surface rugose, except the center and posterior midline with barely punctures. Lateral margin crenulate; lateral angle obtuse, margin between lateral and posterior angle concave. Elytra: Densely punctate with short setae, each elytron with seven longitudinal shallow carinae. Legs: Tibia with rows of setae. Outer margin of protibia serrate with 6–8 lateral teeth. Outer margin of metatibia with a lateral spine. Genitalia: Hemisternite curved outward, apex roundly convex. Spermathecal divided in two branches, each branch with long thin basal duct, length around one-third of bursal duct; apical part hook shaped; base of spermathecal gland located above base of spermatheca branches.

Differential diagnosis. The new species is similar to A. acuminatus , A. chelifer and A. rondoni , but can be distinguished by the characters shown in Tables 1 and 2 .

Distribution. Thailand (Kanchanaburi and Ratchaburi Provinces, Tenasserim Range).

Etymology. The specific epithet “ occidentalis ” is a Latin word meaning western, referring to the species restricted distribution in western Thailand.

Remarks. This species resembles A. rondoni , A. chelifer , and A. acuminatus , but is more closely related to A. rondoni and the females are almost indistinguishable. The distribution of this new species is very close to the northernmost distribution of A. acuminatus , however, sympatric distribution has not yet been found.

Figures

FIGURES 1–14. Aegus spp. male habitus, dorsal view. 1–5, Aegus chelifer Macleay, 1819; 1, Nakhon Ratchasima Province, Thailand; 2, 4, Chiang Rai Province, Thailand; 3, Nakhon Si Thammarat Province, Thailand; 5, Chanthaburi Province, Thailand; 6–7, 9–10, Paratype of Aegus occidentalis Pathomwattananurak & Jiaranaisakul, new species, Ratchaburi Province, Thailand; 8, Holotype of Aegus occidentalis Pathomwattananurak & Jiaranaisakul, new species, Ratchaburi Province, Thailand; 11, Aegus rondoni Bomans, 1971, Sekong Province, Laos.; 12–14, Aegus acuminatus acuminatus (Fabricius, 1801), Nakhon Si Thammarat Province, Thailand.

FIGURES 15–18. Head and pronotum of Aegus spp. large sized male in dorsal view. 15, paratype of Aegus occidentalis Pathomwattananurak & Jiaranaisakul, new species; 16, Aegus rondoni Bomans, 1971; 17, Aegus acuminatus (Fabricius, 1801); 18, Aegus chelifer Macleay, 1819.

FIGURES 19–22. Head of Aegus spp. large sized male in lateral view. 19, paratype of Aegus occidentalis Pathomwattananurak & Jiaranaisakul, new species; 20, Aegus rondoni Bomans, 1971; 21, Aegus acuminatus (Fabricius, 1801); 22, Aegus chelifer Macleay, 1819.

FIGURES 23–30. Male genitalia of Aegus species in dorsal (23, 25, 27, 29) and ventral (24, 26, 28, 30) views. 23–24, holotype of Aegus occidentalis Pathomwattananurak & Jiaranaisakul, new species, Ratchaburi Province, Thailand; 25–26, Aegus rondoni Bomans, 1971, Sekong Province, Laos; 27–28, Aegus acuminatus (Fabricius, 1801), Nakhon Si Thammarat Province, Thailand; 29–30, Aegus chelifer Macleay, 1819, Chiang Mai Province, Thailand.

FIGURES 31–34. Female habitus of Aegus species in dorsal view. 31, paratype of Aegus occidentalis Pathomwattananurak & Jiaranaisakul, new species, Ratchaburi Province, Thailand; 32, Aegus rondoni Bomans, 1971, Quang Binh, Vietnam; 33, Aegus acuminatus (Fabricius, 1801), Nakhon Si Thammarat Province, Thailand; 34, Aegus chelifer Macleay, 1819, Chanthaburi Province, Thailand.

FIGURES 35–39. Female genitalia of Aegus species. 35–36, paratypes of Aegus occidentalis Pathomwattananurak & Jiaranaisakul, new species, Ratchaburi Province, Thailand; 37, Aegus rondoni Bomans, 1971, Quang Binh, Vietnam; 38, Aegus acuminatus (Fabricius, 1801), Nakhon Si Thammarat Province, Thailand; 39, Aegus chelifer Macleay, 1819, Nakhon Si Thammarat Province, Thailand.