Scaptolenus

Martínez-Luque, Erick Omar, Jones, Robert Wallace & Niño-Maldonado, Santiago, 2022, New species, notes on the biology of Scaptolenus LeConte (Coleoptera: Elateridae) and a key to the “ vagans-group ”, Zootaxa 5169 (3), pp. 267-278 : 276-277

Biology of the genus Scaptolenus

Very little is known about the biology of the Cebrionini . Much of the information is based on casual observations obtained in the field, mostly of the genus Cebrio Olivier, 1790 (mainly European), and on some observations generated during the collection of North American species of the genus Scaptolenus . However, a large part of the species of the genus is described from localities of México and Central America. One of the first works in which biological data of this group of insects is presented is in Guérin-Méneville (1844) and Werner (1969). The first observations of the behavior of female individuals is with Scaptolenus fuscipennis ( Fall, 1932) . Collected females of this species were found partially buried in the ground, from where they do not fully emerge which is very similar to that observed in Spain, Italy and France with females of the genus Cebrio . In this genus, females are exposed on the ground and males emerge and fly in search of the females for copulation during and after rainstorms ( Mittré, 1839; Moroder, 1920; Rattu, 2012; 2016; Zapata & Sánchez-Ruiz, 2016). Another genus of Cebrionini that has been reported with very similar activities in females and males, are some species of the genus Selonodon ( Latreille, 1834) , where the females of some species of the genus remain partially exposed in the soil, and the males present a very marked flight activity during the heavy summer rains ( Galley, 1999).

We observed this behavior in Querétaro, México, for an undescribed species of Scaptolenus , where we collected 45 male individuals on the university campus in Juriquilla after one of the first heavy seasonal monsoon rains. Interestingly, all males died in less than 24 hours, suggesting that mating flights are very short and male mortality is high, resulting in a short opportunity for collection, regardless of population size. Subsequently, a search was started at various points in the soil of the scrub vegetation surrounding the campus and some larvae of the genus were collected. In addition, the probable apterous condition of the females and their behavior of remaining buried limit the chances of detection and collection. This also suggests that the genus Scaptolenus may be more common than previously reported, and that collecting larval forms may give a better estimation of population density.

In the case of the new species presented in this work, there are no data associated with their biology. However, the periods in which the specimens of the type series of both species were collected coincide with the rainy seasons in Mexico, which is linked to high levels of environmental humidity and this in turn is related to a flush of vegetative growth and root growth. These rains also produce water saturation and soften soils, which would presumably favor the movement of the larvae and emergence of adults of these edaphic organisms. This seasonality is probably closely linked to the life history events of Scaptolenus in these highly seasonal habitats of tropical deciduous forests.

A key to the groups of Scaptolenus (males) (based on Champion, 1896; Fall, 1932 and Johnson, 2013)

1. Antennomeres with subparallel shape......................................................... chevrolati -group

- Antennomeres without subparallel shape................................................................... 2

2. Antennomeres angularly extended, “L” shaped.................................................... vagans -group

- Antennomeres serrated (in all its variants)......................................................... fulvus -group

A Key to the vagans -group of Scaptolenus (males) (based on Johnson, 2013 and Champion 1896)

1. Antennomeres 4-10 slightly apically dilated................................................................ 2

- Antennomers 4-10 clearly dilated to subangulated ventrally at the apices.............................. S. amplipennis

2. Elytra with inter-grooves flat or slightly elevated; antennae do not reach the middle length of the elytra................. 3

- Elytra with clearly raised striae, giving a sulcate appearance of the striae; antennae longer extending to elytral mid-length.. 4

3. Pronotum wider than the elytral base; head, thorax and scutellum densely covered with long and decumbent fulvous setae; parameres without small spurs at the genital base..................................................... S. vagans

- Pronotum similar in length to the elytral base; head, thorax and scutellum region, moderately lined with separate setation, setae long, fulvous and decumbent; parameres with small sclerotized spines in the first third very close to the genital base, these spines project towards the base and pass behind the middle lobe ( Fig. 10 ).......................... S. zuritai sp. nov.

4. Head, pronotum and scutellum black, which contrast with the chestnut elytra...................................... 6

- Head black, pronotum and scutellum with different coloration from the head...................................... 5

5. Pronotum and scutellum light brown in color similar to the coloration of the elytra; fulvus colored legs......... S. paltingi

- Pronotum and scutellum of testaceous color (yellow-brownish) and elytra of brown color; fuscous colored legs ( Figs. 1-3 )..................................................................................... S. pacofierroi sp. nov.

6. Posterolateral angles of pronotum subparallel; fuscous-colored antennae................................. S. lecontei

- Posterolateral angles of pronotum divergent; fusco-testaceous colored antennae........................ S. acutangulus

Figures

FIGURE 6–10. Scaptolenus zuritai sp. nov.; Figs. 6, 7, 8 dorsal, ventral and lateral view; Figs. 9, 10 ventral and dorsal view of the aedeagus. PHA: phallobase; PAR: paramerous; ML: median lobe; SG: setation group.

FIGURE 1–5. Scaptolenus pacofierroi sp. nov.; Figs. 1, 2, 3 dorsal, ventral and lateral view; Figs. 4, 5 ventral and dorsal view of the aedeagus. PHA: phallobase; PAR: paramere; ML: median lobe; SG: setation group.