Research Article |
Corresponding author: Luiz F. Lima da Silveira ( silveira.lfl@gmail.com ) Academic editor: Vinicius S. Ferreira
© 2022 Luiz F. Lima da Silveira, Marc A. Branham.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Lima da Silveira LF, Branham MA (2022) A new species of Petalacmis firefly from Bolivia, with a key to species (Coleoptera, Lampyridae). ZooKeys 1092: 63-77. https://doi.org/10.3897/zookeys.1092.80464
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Petalacmis Olivier, 1908 is a poorly known genus of firefly endemic to South America and is currently the only member of the subfamily Lampyrinae, tribe Lampyrini known to occur on the continent. Here, we describe a new species, Petalacmis triplehorni sp. nov. from Bolivia and compare it to the two other described species in the genus. A key to Petalacmis species based on male traits, as well as illustrations of morphological features, are given in detail for the first time. We present unique, previously neglected traits of Petalacmis species and compare them to other Lampyrinae.
Firefly, Lampyrini
Petalacmis E. Olivier, 1908 is an interesting and unique genus of fireflies (Coleoptera, Lampyridae) with distinctive antennal morphology: males have only nine antennomeres, the ninth very elongate and paddle-shaped. Petalacmis is poorly represented even in large collections worldwide (LS and MB pers. obs.), and even basic aspects of its morphology are lacking due to the rarity of specimens available for dissection. In fact, this genus is only known from male specimens, a widespread phenomenon in lampyrids (
Petalacmis was erected for its type species, Petalacmis praeclarus E. Olivier, 1908, with no subfamilial placement, by
Petalacmis currently consists of two species: P. praeclarus from Brazil, Bolivia, and Peru, and Petalacmis wittmeri Reichardt, 1963 known only from Brazil. A third species, Petalacmis triplehorni sp. nov. only known from Bolivia, is described here. We provide the first identification key to Petalacmis species based on male morphology and document the morphological features of this genus for the first time. A discussion of Petalacmis morphology and its comparison to other Lampyrinae is presented.
Specimens were both studied and imaged under dissection microscope Leica M205 C. Digital images were obtained and stacked using the Leica Application Suite X. Specimens of P. praeclarus and P. triplehorni sp. nov. were measured under a Leica MZ16 microscope with a calibrated eyepiece graticule, and measurements were converted to millimeters (Table
Comparative measurements (average, range between parentheses) between the three known species of Petalacmis. Measurements were taken from the material examined (see above), except for those of P. wittmeri, which were taken from
Dimensions (mm) | P. praeclarus (n = 8) | P. wittmeri (n = 1) | P. triplehorni (n = 15) |
---|---|---|---|
Total Length | 9.01 (8.13–9.46) | 6.8 | 5.34 (5.06–5.81) |
Pronotal Length | 2.04 (1.74–2.24) | 1.5 | 0.99 (0.91–1.07) |
Elytral Length | 7.02 (6.39–7.3) | 5.3 | 4.35 (4.15–4.73) |
Lampyridae: Lampyrinae: Lampyrini
The three species of Petalacmis are easily diagnosable by size (Table
Color pattern: overall brown, except for the dark brown pronotal disc, translucent parasagittal rounded spots on pronotal expansions, and translucent sterna VI–VIII (Fig.
Head
: head capsule about 1/3× wider than long, posterior margin almost straight, except for the dorsal margin of occiput, which is rounded (see dorsal view, Fig.
Thorax
: pronotum with anterior margin slightly sinuose and acuminate anteriorly (Fig.
Petalacmis triplehorni sp. nov., male thorax. A–E prothorax: A dorsal B ventral C anterior D posterior E lateral. F–K pterothorax: F mesoscutellum, dorsal G alinotum, dorsal H pterothorax, ventral I pterothorax, dorsal (detail of meso and metaendosterna J alinotum, dorsal K pterothorax and abdominal tergum I, lateral L–N wings: L elytron, dorsal M elytron, lateral (outer view) N left wing, dorsal O, P legs: O left pro, meso and metaleg (left to right) P detail of left pro, meso and metaleg apices (left to right). Scale bars: 500 µm (A–K); 1 mm L–N; 750 µm (O); 250 µm (P).
Alinotum overall weakly sclerotized, slightly wider than long (Fig.
Abdomen
: tergum I with laterotergite membranous, roughly triangular, almost indistinct (Fig.
Petalacmis triplehorni sp. nov., male abdomen A–C core abdomen (segments IV–VIII) A dorsal B lateral C ventral D–F aedeagal sheath D dorsal E lateral F ventral G–J aedeagus (distal tips oriented toward top of the figure) G apical/posterior H dorsal I lateral, J ventral. Scale bars: 500 µm (A–C); 250 µm (D–I).
Unknown.
This species is named for Dr Charles “Chuck” Triplehorn, Professor Emeritus of the Ohio State University, who collected the first specimens of Petalacmis praeclarus that one of us (MAB) first encountered as a graduate student while investigating the systematics of the family Lampyridae. Dr Triplehorn has been both a mentor and an inspiration to MAB. It is with great appreciation and respect for Dr Triplehorn that we name this species after him.
Holotype
, male. Bolivia: Santa Cruz, Potrerillo del Guendá Reserve, 1322’ elev., 17°40.262'S, 63°27.445'W, at light, J. McHugh lab exped. leg., 6–12-I-2005 (
Paratypes
(n = 14). Bolivia • Santa Cruz, Potrerillo del Guendá Reserve.; 1322’ elev.; 17°40.262'S, 63°27.445'W; at light; J. McHugh lab exped. leg.; 6–12-I-2005 (1 ♂, USNM) • Santa Cruz, 3.7 km SSE of Buena Vista, Hotel Flora and Fauna; 405 m elev.; 5–15-XI-2001; 17°29.949'S, 63°33.152'W; M.C. Thomas & B.K. Dozier leg.; tropical transition forest (3 ♂,
1 | Elytron subparallel-sided, slightly tapering distally (Fig. |
2 |
– | Elytra elliptical, widest in middle (Fig. |
Petalacmis wittmeri Reichardt |
2 | (1). Antennomeres V and VII as wide as VI and VIII, apical antennomere nearly 2× longer than remaining antennomeres together (Fig. |
Petalacmis praeclarus E. Olivier |
– | Antennomeres V and VII slightly longer and wider than neighbor antennomeres, apical antennomere as long as the remaining antennomeres together (Fig. |
Petalacmis triplehorni sp. nov. |
Brazil: Minas Gerais, Lambari [spelled Lambary], XI.1924, J. Halik col. (1 male, USNM 3083) // Brazil Halik 1966 coll.; same data, XI.1924 (1 male, USNM 3084); same data, XI.1924 (1 male, USNM 3085); São Paulo, São Paulo, Santana [spelled St. Anna, Cap. S. Paulo], XII.1934, J. Halik col. (1 male, USNM 5047).] // Brazil Halik 1966 coll. collection; São Paulo, Cantareira, 23.VII.1933, J. Halik col. (1 male, USNM 2208) // Brazil Halik 1966 coll. collection; São Paulo, Botanical garden [spelled horto flor.], XII.1921, J. Halik col. (1 male, USNM 7190) // Brazil Halik 1966 coll. collection; São Paulo, Piracicaba, 6.X.1965, Blacklight, C. A. Triplehorn col. (2 males, M. Branham collection).
To date, all Petalacmis species are known from lowland localities across South America east of the Andes. Petalacmis praeclarus was described from “Brazil”. It has since been collected in Bolivia and Peru (
Due to the presence of large eyes and photic organs in the male, one might expect that both the male and female of these species are luminous and use luminous signals for pair-formation, as seen in several firefly subfamilies (
The affinities of Petalacmis have been investigated in two comprehensive phylogenies of Lampyridae. Based on morphological data,
As our study was the first to thoroughly survey the anatomy of Petalacmis, we provide some comparisons to inform the ongoing debate on the phylogenetic affinities of this genus. We assume that our description of P. triplehorni sp. nov. includes traits that are likely to be shared with other species in the genus, or even traits common to all of them. In addition to the very distinctive “petal-like” antennal morphology, we observed previously obscured traits of Petalacmis that differ significantly from those of other lampyrine genera. For example, Petalacmis is unique among lampyrine genera in having (i) an intumescent and laterally keeled frons (Fig.
Another trait shared with all three amydetine genera (Amydetes Illiger, 1807, Magnoculus McDermott, 1964, Memoan Silveira & Mermudes, 2013;
Concerning aedeagal morphology, lampyrine taxa very often have parameres with an elongate, membranous apex—a trait also commonly found across Lamprocerini and Cratomorphini (e.g.,
Recently, it has become more common that taxonomic studies report detailed exo- and endoskeletal traits of the thorax, like the shape of meso and metatergal ridges, as well as those of the endosternites. Currently, no such information is available for any taxa of Lampyrini, which hampers any comparison. Nevertheless, we observed some interesting traits in Petalacmis triplehorni sp. nov. and compare it to known lampyrine taxa. For instance, the mesoscutellum of P. triplehorni sp. nov. is so reduced that it is almost triangular, despite the median pointed projection at the posterior margin (Fig.
The alinotum of P. triplehorni sp. nov. is clearly distinct, with a scutum–prescutal ridge that extends to less than half the length of the metanotum (Fig.
Petalacmis shares with Lampyrini, Pletomonini, and Lamprocerini, the ventral position of abdominal spiracles, as well as the reduced mandibles. However, this genus lacks key traits of all these three tribes. For example: both Lucio and Lamprocera, the taxa placed close to Petalacmis in
Taken together, these observations highlight the potential value of traits typically neglected in lampyrid taxonomy, and invite future anatomical studies concerning the Lampyrinae, particularly the Lampyrini. We hope that our study fosters a future comprehensive review of this interesting firefly genus.
We thank Charles Triplehorn for collecting the specimens that made MAB aware of this genus and for being a great friend and mentor, Cleide Costa for comparing the new species to the holotype of Petalacmis wittmeri, Michael Thomas for collecting the series of specimens described in this manuscript and making them available for study, James E. Lloyd and Paul “Skip” Choate for commenting on an early draft of the manuscript, Vinicius S. Ferreira and Francisco Eriberto Nascimento for the pictures of P. wittmeri (Fig.
Figure S1
Data type: Figure
Explanation note: Petalacmis triplehorni sp. nov. habitus of one of the paratypes (note lantern morphology and the brighter pronotal expansions) A dorsal B ventral.