Nigidius gravelyi Paulsen, 2018

Paulsen, M. J., 2018, Revision of the obesus species group of the stag beetle genus Nigidius MacLeay (Coleoptera: Lucanidae: Lucaninae: Figulini), Insecta Mundi 2018 (624), pp. 1-13 : 9-11

Nigidius gravelyi Paulsen , new species

Type material. Holotype male ( Fig. 5 ), ex MJPC, deposited at FSCA, labeled: a) “ INDONESIA / East Kalimantan / Mt. Payang V.2011 ”; b) on red paper, “ HOLOTYPE / Nigidius gravelyi / Paulsen, 2014”. Type locality: Indonesia: East Kalimantan: Mt. Payang.

Paratypes (n = 41 ♂, 56 ♀). Paratypes (9 ♂) with locality label as holotype . Paratypes (11 ♂, 15 ♀) labeled: “ INDONESIA: Kalimantan / August , 2011”. Paratypes (3 ♂, 2 ♀) labeled: “ INDONESIA / Kalimantan / V.2010 ”. Paratype (1 ♂) labeled: “ INDONESIA / Borneo / Jan 2008 ”. Paratypes (1 ♂, 9 ♀) labeled: “ INDONESIA / Kalimantan / no date” . Paratypes (5 ♂, 5 ♀) labeled: “ INDONESIA / Kalimantan / February , 2011” . Paratype (1 ♀, SLTC) labeled: “BORNEO Sabah / Crocker Range NP / IV – V 2008 / Tropical forest, elev / 1200 m, local coll.” . Paratypes (2 ♂, 8 ♀) labeled: a) “ INDONESIA: Borneo / (S. Kalimantan) Prov. / Meratus Mountains / VII.2015; local coll.” . Paratype (1 ♀) labeled: “ MALAYSIA: N / BORNEO, Sabah / Crocker Range /coll. 24.IX.2006 ” . Paratype (1 ♂, NHM) labeled: a) “ J. Devecis / Tenom 900 m / Crocker’s Range / Sabah 30-IV-93”; b) “H. Bomans det 19[93] / Nigidius / [ obesus Parry ]”; c) “17784”; d) “ H.E. Bomans / BMNH(E) / 1999-248” . Paratype (1 ♀, CMNC) labeled: “Borneo Sabah Mt. / Kinabalu Nat. Pk. / Poring Hot / Springs 520m / 13.V.87 A. Smetana ” . Paratypes (3 ♂, 5 ♀, NHM) labeled: a) “ Borneo Occ. / Pontianak / 1900” . Paratypes (2 ♂) labeled: a) “ Borneo Occ. / Pontianak / 1900”; b) “ Ritsema / vidit 1903” . Paratypes (1 ♂, 2 ♀, ZMHB) labeled: a) “ Borneo Occ. / Pontianak / 1900” . Paratype (1 ♀, TAMU) labeled: a) Malaysia, Sabah / Ranau / V-3-2006 / local coll.” . Paratype (1 ♀, FMNH) labeled: a) “N. Borneo ”; b) “Coll. Dr. Ed. Knirsch / [Nigid. kina - / baluensis Rits. ] / Determ. Dr. Knirsch ”; c) handwritten “ Nigidius / obesus / Parry”, on obverse “Det. / B. Benesh / 27-9-’58”; d) “ H. Bomans det., 19[86] / Nigidius / [ obesus Parry ]” . Paratype (1 ♀, FMNH) labeled: a) “N. Borneo ”; b) “ Coll. Dr. Ed. Knirsch / [Nigid. kina - / baluensis Rits. ] / Determ. Dr. Knirsch ”; c) “CNHM 1957 / Eduard Knirsch / Lucanid Collection ”; d) “ H. Bomans det., 19[86] / Nigidius / [ obesus Parry ]” . Paratype (1 ♀, MFC) labeled: a) “ Malaysia: Sabah / Crocker Range / near Kimanis Rd. / 1-31.III.2008 / local collector” . Paratype (1 ♂, MFC) labeled: a) “Trus Madi / Sabah N. Borneo / E. Malaysia / Feb. 2004.” Paratype (1 ♀, MJPC) labeled: a) “ Kimanis Road / Sabah N. Borneo / Malaysia / 1-20.IV.1998; Coll. N. Okuda. ” Paratype (1 ♀, NOC) labeled: a) “Kimanis Road / near Keningau / Sabah Malaysia / 1-20.IV.1998 ” . Paratype (1 ♂, NOC) labeled: a) “ Near Keningau / Sabah Borneo I. / Malaysia / 28-III~ 12.IV.1994; Coll. N. Okuda. ” Paratype (1 ♀, NOC) labeled: a) “ INDONESIA / South Kalimantan / Tanah Bumbu / Batulicin ; VI.2007 ”. All paratypes labeled, on yellow paper: “ Nigidius gravelyi / Paulsen / PARATYPE ”. Some paratypes without acronyms in this list will be deposited from MJPC to CASC, FMNH, FSCA, MHNG, NHM, SLTC, and ZMUC .

Description, holotype. Coleoptera : Scarabaeoidea: Lucanidae : Lucaninae : Figulini. Length: 17.4 mm. Width: 7.6 mm. Color: Piceous. Head: Surface shiny, punctate, punctures with long setae anteriorly; punctures coarse, ocellate, and dense on frons, fine and sparse on clypeus. Frontoclypeal area impunctate. Clypeus short, emarginate on each side, apex truncate. Labrum visible dorsally. Eyes completely divided by ocular canthus, canthus consisting of a declivous rounded anterior portion, deep emargination, then posterior ovoid lobe adjacent to eye; lobe rounded anteriorly, sinuate posteriorly with posterior angle subacute; lobe coarsely punctate. Antennal club small, shorter than scape, antennomeres 8 and 9 of club tomentose only distally, antennomere 10 tomentose except for semicircular proximal area. Mandibles (to true apex) shorter than head, apex tridentate. Dorsal surface produced into long, vertical curved ramus (false apex); ramus with basal lobe posteriorly. Mentum broad, bilobed, surface coarsely but shallowly punctate. Labial palp with terminal palpomere ovoid. Pronotum: Form short, wider than elytra. Anterior angles explanate, about 1/3 length of pronotum. Surface variable on disk with subfoveate areas of coarse, dense punctures contrasting with almost impunctate areas with only fine punctures; anterior ridge elevated and appearing impunctate (fine punctures present); longitudinal median furrow coarsely punctate. Setae of coarse punctures prominent laterally. Elytra: Form parallel-sided. Surface with serially punctate, impressed striae with broad, weakly convex intervals; striae with coarse, ocellate, horseshoe-shaped, almost contiguous punctures; intervals 1–4 punctate with fine, shallow punctures in 2–3 irregular rows. Setae of coarse punctures prominent laterally. Legs: Protibia with 6 acute teeth decreasing in size proximally. Meso- and metatibiae with 1 large external tooth below middle with 1–2 smaller accessory teeth proximally. Abdomen: Male genitalia ( Fig. 12 ) with permanently everted internal sac (flagellum) with lateral margins more or less straight when manually extended (vs. more sinuate in other species), but one side with large, lateral lobe well-removed from simply tubular apex.

Paratype variation. Males (n = 41). Length: 13.7–19.3 mm. Width: 5.7–7.9 mm. Females (n = 56). Length: 14.7–17.7 mm. Width: 6.0–7.0 mm. Females and males less than 14.4 mm with posterior lobe of dorsal ramus of the mandibles narrower, subacute.

Etymology. The species is named in honor of F. H. Gravely, who described another valid species in this group, N. dawnae , which has at times been overlooked.

Distribution. The species is known only from the island of Borneo, occurring in both Kalimantan, Indonesia and East Malaysia ( Fig. 14 ).

Remarks. Nothing is known of the life history of this species. The more or less straight flagellum of the male genitalia when extended is unique; the remaining species have flagella that are more sinuous. Elytral intervals 2–4 are irregularly punctate, not almost impunctate medially as in N. obesus . It is distinguished from N. helleri by the less regularly punctate pronotum with clusters of fine punctures that appear as impunctate areas and the more strongly produced anterolateral projection on the pronotum. In this species, males less than 14.4 mm in length from the clypeal apex to elytral apex cannot be distinguished from females by the basal tooth of the mandibles, and genitalic dissection is required to determine sex. In specimens over 14 mm the basal tooth is sexually dimorphic.

Figures

Figure 5. Nigidius gravelyi Paulsen, n. sp., holotype male, with labels (inset).

Figure 14. Distribution of obesus group species: N. obesus (triangles), N. dawnae (squares), N. gravelyi Paulsen, n. sp. (diamonds), N. helleri (circles).

Figures 10–13. Male genitalia of obesus group species. 10) N. obesus. 11) N. dawnae, arrow indicates small apical lobe. 12) N. gravelyi Paulsen, n. sp. 13) N. helleri, arrow indicates large lateral lobe.