Pteroptyx decolor Olivier, 1911 a

Jusoh, Wan F. A. & Ballantyne, Lesley, 2024, A catalogue and redescription of type specimens of fireflies (Coleoptera, Lampyridae, Luciolinae) deposited in Naturalis Biodiversity Center, Leiden, Contributions to Entomology 74 (1), pp. 63-80 : 63-80

Pteroptyx decolor Olivier, 1911 a

Fig. 5 A – N

Pteroptyx decolor Olivier, 1911 a: 17. Olivier 1913: 55. McDermott 1966: 117. Ballantyne and McLean 1970: 248. Ballantyne 2001: 63. Jusoh et al. 2018: 29, figs 57–66.

Lectotype.

1 ♂ (herein designated).

Type locality.

“ Atjeh ”.

Material examined

(1 ♂ specimen). Lectotype (herein designated): INDONESIA ● ♂: (1) “ Atjeh ”; (2) “ Coll. Veth ”; (3) “ Pteroptyx / decolor / Ern. Oliv. ”; (4) “ RMNH Leiden / ex Indo-Austr. / collection ”; (5) “ RMNH. INS / 968355 ” (Fig. 5 A ).

Diagnosis.

Very pale yellowish brown dorsal colouration, with elytra semi-transparent and globules of fat body showing beneath pronotal cuticle; ventral surface very pale brown, with globular fat bodies visible beneath abdominal ventrites, LO in V 6, 7 cream; labrum (partly obscured) antennae, palpi and tarsi dark brown, head between eyes yellowish brown. P. decolor belongs to that group of Pteroptyx which do not have paired lobes to either side of T 8 emargination, the deflexed elytral apices are elongated and not dimpled on the posterior margin, the posterolateral corners of V 7 are rounded and scarcely produced, and the MPP of V 7 has a flat dorsal surface with a short posterior prolongation. Most similar to P. valida from which it is distinguished by the paler colour ( P. valida has black elytral apices) and its occurrence in Indonesia.

Redescription of lectotype male.

Body length (Fig. 5 B ). 7 mm long.

Colour (Fig. 5 B – D ). Dorsally light brownish yellow with all areas slightly semi-transparent except V 6, 7; pronotum slightly more orange yellow than elytra (Fig. 5 B ); MS, MN concolourous with elytra; head between eyes pale yellow; eyes black, antennae (except for brownish orange basal ¾ of scape) and palpi dark brown; labrum (partly obscured) pale yellow with basal half brown (Fig. 5 C ); venter of thorax pale yellowish brown, metathorax appearing slightly mid-brown because of dehydrated, underlying muscles visible through semi-transparent cuticle; legs yellowish, legs 1 with dark brown tarsi; legs 2 incomplete; legs 3 with coxae coloured as for ventral metathorax, basal 2 tarsomeres yellow, apical 3 dark brown; deflexed elytral apices yellowish; abdomen yellowish with underlying fat bodies in V 3–5 visible; LO in V 6, 7 yellowish dirty cream (Fig. 5 D ).

Pronotum. With lateral margins subparallel-sided, posterior angles almost 90 °, anterolateral corners rounded obtuse.

Elytra (Fig. 5 B, D , see arrows). Elytral deflexed apex wide, long, apically truncated; Fig. 5 D shows longitudinal groove on both deflexed areas similar to that seen in P. valida ( Ballantyne 2001: fig. 51 stippled area; Ballantyne and Menayah 2002: fig. 7; Jusoh et al. 2018: fig. 202).

Abdomen (Fig. 5 D – I ). LO in V 7 bipartite, inner margins incline medially. MPP of V 7 as described for P. valida ( Jusoh et al. 2018: figs 205–209) with a slightly wider and shorter bifurcated projection from dorsal surface (Fig. 5 E – G ; arrowed in Fig. 5 E, G ). T 8 median posterior margin emarginated, areas beside emargination slightly sinuous; posterolateral corners rounded; anterior paired prolongations wide, semi parallel-sided, with rounded apices; ventral surface with wide median groove margined by ridges running slightly obliquely from posterior margin for ⅓ length of tergite; margins elongated at anteromedial area into flanges with rounded apices (Fig. 5 H, I ; area of flanges arrowed in Fig. 5 I not clearly visible).

Aedeagal sheath (Fig. 5 J, K ): elongate slender symmetrical; sheath sternite expands to its widest point where it articulates laterally with the tergite arms, then diminishes in width towards its rounded apex (Fig. 5 K paired oblique upper arrows indicate widest margin of sternite); sheath tergite in two sections, posterior section narrows and is apically rounded; anterior section with anterior margin deeply and evenly emarginated, extending at the sides into bulbous pieces (‘ paraprocts’ oblique arrows in Fig. 5 J ) (Fig. 5 J, K ).

Aedeagus (Fig. 5 L – N ). LL 0.7 length of ML (distances measured along dorsal surface only from base of lateral lobes); LL separated along their dorsal length for approximately half their length. Attachment of ML to LL: base of ML wide, inner dorsal margin abuts the inner dorsal area of LL well behind their anterior margin (Fig. 5 M, N ; upper arrow Fig. 5 M, N anterior dorsal margin LL; lower arrow area of attachment of ML to inner surface LL).

Notes.

In Olivier’s original description, he described Pteroptyx decolor based on a male from “ Atjeh ” and a female from “ Borneo ” ( Olivier 1911 a: 17). He did not name a depository or designate a holotype but mentioned that the specimens were in his collection (“ Ma coll. ”). Until now, and without any type material, the identification of specimens as Pteroptyx decolor has been based primarily on their locality (Borneo) and their pale dorsal colouration.

Ballantyne and McLean (1970: figs 8 a – i) addressed a female paratype, and 15 males and 25 females from Sarawak. They did not recognise the significance of the “ Atjeh ” label on Olivier’s male specimens and indicated the species was restricted to Borneo. The pale dorsal colouration included a pale head (between the eyes) with dark brown labrum, and dark markings at the extreme elytral apex which were not always visible from above. Ballantyne (2001) examined a further 4 males and a female collected in Saratok by Polunin, which were otherwise consistent with those described in Ballantyne and McLean (1970).

Jusoh et al. (2018) discussed the uncertainty around the identification of this species and inadvertently permitted the conclusions we present here by the characters used in their key to males.

In Jusoh et al. (2018) four species were characterised with well-defined lobes alongside the median posterior emargination of tergite 8 viz. Pteroptyx asymmetria Ballantyne, 2001 , Pteroptyx bearni Olivier, 1909 , P. decolor and Pteroptyx tener Olivier, 1907 . Only P. asymmetria has a strongly asymmetrical posterior margin to tergite 8 ( Jusoh et al. 2018: figs 17, 20). Of the three remaining P. tener does not have the posterior margin of T 7 emarginated (it is slightly sinuous) and the posterolateral corners of V 7 are angulate and scarcely produced ( Jusoh et al. 2018: figs 162–165). The two remaining species “ P. decolor ” and P. bearni differ most obviously in colour ( “ decolor ” was described as very pale dorsally, while bearni has dark elytra and pinkish orange pronotum). The outlines of V 7 and T 7 and 8 are similar, but “ decolor ” has the projections to each side of the T 8 emargination broadly rounded, while in bearni they are narrow and acute ( Jusoh et al. 2018: figs 39–40, 44, 45, 57–59, 64–65).

It is very probable that the following references to P. decolor are a presently undescribed species: Ballantyne and McLean (1970) reference to 15 males and 25 females from Sarawak; Ballantyne (2001) reference to 4 males, female taken in Saratok. The species may be restricted to the island of Borneo and appears close to P. bearni differing in the broadly rounded paired projections beside the T 8 emargination.

We herein designated a lectotype for Pteroptyx decolor to reduce the potential for confusion, especially considering previous misidentifications.

Figures

Figure 5. Pteroptyx decolor Olivier, 1911 lectotype male. A. Specimen labels; B. Dorsal habitus; C. Ventral anterior body including head; D. Ventral abdominal apex and apex left elytron; E – G. V 7 ventral view (E), dorsal view (F), and G posterior with ventral surface uppermost (projection of tip of MPP of V 7 arrowed in E, G). H – I. T 8 dorsal and ventral (oblique arrows in I indicate position of flanges); J – K. Aedeagal sheath: J. Ventral view; K. Dorsal view (paraprocts arrowed in J; widest margin of sternite arrowed in K); L – N. Aedeagus: L. Ventral view; M. Dorsal view; N. Right lateral (upper arrows M, N anterior dorsal margin of LL; lower arrows M, N attachment of ML to inner surface of LL). All images are to scale, except specimen labels.