Oculogryphus is a small beetle genus currently composed of two species known only from northern Vietnam (Jeng et al. 2007, 2011). The genus is morphologically distinctive in having enlarged compound eyes which are closely approximate ventrally and deeply emarginate on the posterior upper margin laterally. It was thought to be en enigmatic taxon with a mosaic of features intermingling those of Rhagophthalmidae, Luciolinae, Lampyrinae, and the ototretine-ototretadriline complex when established (Jeng et al. 2007). Subsequently the genus was revealed to be closely related to the ototretine genus Stenocladius Fairmaire s.str. based on a comprehensive phylogenetic study of Lampyridae based on male morphology (Jeng 2008, Jeng et al. 2011). In the most current revision of Ototretinae, Janisova and Bocakova (2013) synonymized the subfamily Ototretadrilinae and accordingly redefined the limits of the group. Eighteen ototretine genera were reviewed or revised, diagnostically characterized, and a key based on male characters, especially of aedeagal morphology, was given, but Oculogryphus was overlooked.

Here we describe a third species of the genus, recently collected in Sichuan Province, China. The new species is the first representative of the genus in the Sino-Japanese zoogeographic realm (sensu Holt et al. 2013). Some morphological variations of Oculogryphus and Stenocladius are discussed in detail and a modification to Janisova and Bocakova’s (2013) key to ototretine genera is proposed so as to include Oculogryphus.

The methodology and morphological terminology used herein follows that of Jeng et al. (2007, 2011). The body length (BL) is the sum of the pronotal and elytral lengths (PL and EL, respectively) plus length of those exposed portions of the head from the pronotum. Body width is considered as twice the elytral width (BW = 2EW). Pronotal width is abbreviated as PW. The nomenclature of the hind wing venation follows that of Kukalová-Peck and Lawrence (2004). In reporting label data the symbol “/” indicates separate lines on a single label. The holotype will be deposited in the insect collection of the Chinese Academy of Sciences, Beijing (CAS) and the paratype in the National Museum of Natural Science (NMNS), Taichung, Taiwan.

We examined the type material of the type species and several other species of the ototretine genera deposited in the Muséum national d’Histoire naturelle, Paris (MNHN). Oculogryphus is doubtless a member of the newly-defined Ototretinae and appears allied to a subgroup whose lateroposterior angles of the pronotum are less prominent. Following Janisova and Bocakova’s (2013) key, Oculogryphus falls intermediate between Falsophaeopterus Pic and Stenocladius in couplet 17 – it shares filiform antennae with Falsophaeopterus but has an aedeagal morphology more resembling that of Stenocladius. Although similar, the morphological particulars of Oculogryphus differ notably from the other two genera. For example, the filiform antennae of Oculogryphus are comparatively short and slender in relation to those of Falsophaeopterus which are more or less depressed, long and varyingly serrate. As to the aedeagus, the length of the parameres in relation to the phallus (median lobe) and whether the phallobase (basal piece) has a marginal emargination were used to separate Stenocladius from Falsophaeopterus in Janisova and Bocakova’s (2013) key. It is true that the parameres of Falsophaeopterus (including its subgenus Mimophaeopterus Pic) are about as long as the phallus, but this is quite variable in Stenocladius (as long as 2/3 of the phallus to slightly shorter (6/7), (cf. Kawashima 1999, Janisova and Bocakova 2013)). The ratios of phallus/phallobase and paramere/phallobase also varied greatly among species of Stenocladius but seem stable in Falsophaeopterus, which always has the phallobase shortest among the aedeagal sclerites. The ratios of aedeagal sclerites of Oculogryphus show a pattern similar to that observed for Stenocladius (Jeng et al. 2007, 2011, present study). The notch on caudal margin of the phallobase is quite clear in the type species of Stenocladius, Stenocladius davidis Fairmaire (Janisova and Bocakova 2013), but is faint or absent in some others (Kawashima 1999). Similar variation exists among species of Oculogryphus, too (Jeng et al. 2007, 2011, present study). The aforementioned features appear not sufficiently reliable to be diagnostically meaningful in differentiating these genera in a key.

Oculogryphus is distinct from all of the other ototretine genera by its large compound eyes which are nearly contiguous ventrally and significantly emarginate on the posterior upper margin in males. The genae are mostly vertical, deeply lying between the enlarged compound eyes and separated by a fused gular suture (Fig. 2). Within Ototretinae, only a few unidentified species of Stenocladius from China and SE Asia are comparable to Oculogryphus in terms of compound eye size. Generally the compound eyes of species of Stenocladius are of median size, hemispherical frontally, nearly spherical laterally and separated from each other ventrally by 0.9× to 1.5× ventral width of an individual compound eye (Janisova and Bocakova 2013). The genae and gula between the compound eyes are visible ventrally. In contrast, the large-eyed species of Stenocladius have their compound eyes approximate ventrally, separated from each other by scarcely visible genae and a narrow gula and are weakly and broadly-rounded emarginate on the posterior margin. Simultaneously, they also possess shorter antennae and antennal branches in contrast to the typical species of the genus. The combination of enlarged compound eyes and short antennae is likely a character suite adapted to a visually-oriented mate-searching strategy at night. Though enlarged and deeply emarginate compound eyes have evolved in parallel or by convergence among several lampyrid (Ototretinae, Luciolinae, and Lampyrinae) and rhagophthalmid (Rhagophthalmus Motschulsky, Menghuoius Kawashima and Satô, and Dioptoma Pascoe) lineages (Jeng et al. 2007), those of Oculogryphus are unique to the newly-defined Ototretinae. Herein we proposed a modification to Janisova and Bocakova’s (2013) key, partially adopted from Jeng et al. (2007) to include Oculogryphus: