Key to genera of Luciolinae using males

Keys to genera of the Luciolinae, beginning with Ballantyne & McLean (1970), addressed increasing numbers of genera as the taxonomy expanded, but have never included either Luciola cruciata or L. owadai (see review in Ballantyne et al. 2019). It is possible to distinguish Nipponoluciola gen. nov. from other Luciolinae genera by the following, without the need for a complicated generic key.

Of those Luciolinae genera with LL visible at the sides of the ML, only two genera have a narrow base to the elytral epipleuron such that the elytral humerus is visible from beneath if the specimens are held horizontally (Fig. 3), Missimia and Nipponoluciola gen. nov. Missimia (Figs 4E‒H; Table 1) is a rare genus known from four specimens collected in the New Guinea highlands, distinguished most obviously from Nipponoluciola by its pale brown dorsal colouration, its distribution in the New Guinea highlands, the acute posterolateral corners of the pronotum in males, the inflexible nature of the clypeolabral suture, the absence of a median notch in the aedeagal basal piece, and the presence of a well-defined and depressed area on the outer margins of the lateral lobes of the aedeagus bearing setae (Ballantyne & Lambkin 2009: figs 21–22, 27, 29–30, 32‒34, 246‒254). The two species of Nipponoluciola have black elytra, are known only from Japan including the Ryukyu Islands, the posterolateral corners of the pronotum are rounded, the clypeolabral suture is flexible, most aedeagi examined have a median notch in the basal piece, and there is no depressed setae bearing area on the outer margins of the lateral lobes of the aedeagus (Figs 1, 2G‒H, 5).

List of genera of Luciolinae having aquatic larvae

Fu et al. (2010) noted that verified records of aquatic firefly larvae are rare, and given that original descriptions rarely give any indication of any larval associations or accurate habitat data, that adults are often described without knowledge of the larval types. It is thus possible that the incidence of aquatic Luciolinae will ultimately be shown to be wider than the range we address here.

Fu et al. (2012b) defined aquatic larvae as possessing either gills along the sides of the abdomen*, or having spiracles only at the end of the abdomen # (metapneustic). Those marked with superscript J are from Japan.

The following list includes genera and species for which confirmation of aquatic larval status exists.

Aquatica Fu et al., 2010 *

A. ficta (Olivier, 1909)

A. hydrophila (Jeng et al., 2003)

A. lateralis (Motschulsky, 1860) J

A. leii (Fu & Ballantyne, 2006)

A. wuhana Fu & Ballantyne, 2010

Sclerotia Ballantyne, 2016 #

S. aquatilis (Thancharoen, 2007)

S. flavida (Hope, 1845)

S. fui Ballantyne, 2016

Nipponoluciola gen nov.*

Nipponoluciola cruciata (Motschulsky, 1854) gen. et comb. nov. J

Nipponoluciola owadai (Satô & Kimura, 1994) gen. et comb. nov. J

Key to genera of Luciolinae having aquatic larvae using males

1. In horizontal specimen, viewed from beneath, elytral epipleuron narrow at base and elytral humerus clearly visible (Fig. 3A); elytra very dark brown to black with no paler margins; at least two interstitial lines well defined; elytral punctation not subparallel-sided; aedeagal sheath with both left and right sides of sheath sternite posterior to tergite articulations smoothly emarginated (Figs 1–3, 5) ........... .................................................................................................................... Nipponoluciola gen. nov.

– In horizontal specimen, viewed from beneath, elytral epipleuron wide at base and elytral humerus not visible (as in Fig. 3D); elytral colour variable, often pale brown with black tips; interstitial lines well defined or not; elytral punctation may be subparallel-sided; aedeagal sheath sternite either little emarginated on both sides, and approximately subparallel-sided (Fig. 4M) or quite deeply emarginated more on right than left side, with both sides of sheath sternite posterior to the tergite articulations bearing short toothlike projections (Fig. 4C) ............................................................... 2

2. Dorsal colouration usually brownish-yellow, with or without dark brown elytral apices (Fig. 4I); one species has mid brown elytra with pale coloured interstitial lines and margins; elytra with subparallel-sided punctation (Fig. 4I); interstitial lines either evanescent or up to four well defined lines present; light organ in ventrite 7 with anterior median emargination, lateral and posterior margins of light organ usually almost reaching the lateral and posterior margins of ventrite 7 (Fig. 4J); tergite 8 with elongated slender anterolateral projections; lateral margins of abdominal tergite 8 usually enfold the sides of ventrite 7 (Fig. 4M); set of three sclerites (two lateral and one ventral) surrounding the aedeagal sheath in a ring of muscle, may be visible from above through the terminal abdominal tergites (Fig. 4L–N show two of the three sclerites); aedeagus short and squat (L/W <3) (Fig. 4K); basal piece long, narrow, reaching posteriorly at the sides of the lateral lobes for about 0.4‒0.6 aedeagal length, and not medially emarginated; aedeagal sheath asymmetrical in posterior half where sheath sternite inclines to the left; sternite not angulated on either side, posterior area subparallel-sided, and posterior margin either emarginated, truncated, or prolonged on one side (Fig. 4M) ...................... Sclerotia Ballantyne, 2016 (Ballantyne et al. 2016: figs 17‒38); Fig. 4 I‒N

– Dorsal colouration with brownish-yellow pronotum, often with median dark markings, and dark brown elytra which may be pale margined (e.g., Fig. 4A); one species has mid brown elytra with pale margins; elytra without subparallel-sided punctation; interstitial lines not well defined; light organ in ventrite 7 without anterior median emargination, reaching sides but not posterior margin of ventrite 7 (light organs usually retracted to anterior half of ventrite 7) (Fig. 4B); tergite 8 anterolateral projections either very short or absent; lateral margins of abdominal tergite 8 do not enfold the sides of ventrite 7; no sclerites surrounding the aedeagal sheath (Fig. 4C); aedeagus longer than wide (L/W ≥ 3) (Fig. 4D); basal piece not narrow, not reaching posteriorly at the sides of the lateral lobes for about 0.4‒0.6 aedeagal length, usually in two pieces and not medially emarginated; aedeagal sheath asymmetrical in posterior half where sheath sternite does not incline to the left, and may be irregularly emarginated on both sides with both sides bearing at least one toothed projection; sternite appears angulated on each side in two species; posterior margin of sternite either rounded or very shallowly medially emarginated ......................................................................................................... ................................ Aquatica Fu et al., 2010 (Fu et al. 2010: figs 2‒24, 27‒29, 32‒43); Fig. 4A‒D

Key to aquatic larvae in the Luciolinae

Fu et al. (2012b) keyed the genera listed above from larvae. They addressed five species of Aquatica (Fu et al. 2012b: figs 1‒24, 61–62, 67–68, 73‒80, 91), two species of Sclerotia which were still attributed to Luciola (Fu et al. 2012b: figs 31‒42, 70, 83‒86), and two species of Nipponoluciola gen. nov. which were also still attributed to Luciola (Fu et al. 2012b: figs 25‒30, 69, 81–82). See also Fu et al. (2010: figs 25–26, 30–31, 44‒49) for Aquatica larvae.