Graphipterus serrator ( Forskal , 1775): 77

Renan, Ittai, Assmann, Thorsten & Freidberg, Amnon, 2018, Taxonomic revision of the Graphipterusserrator (Forskal) group (Coleoptera, Carabidae): an increase from five to 15 valid species, ZooKeys 753, pp. 23-82 : 53-55

Graphipterus serrator ( Forskal, 1775): 77 Figs 1, 3f, 4b, 4c, 5, 6a, 7, 9m, 10a, 14, 19, 26b, 28b, c, d

Carabus serrator Forskål, 1775: 77 (Aegypten)

Carabus variegatus Fabricius, 1781: 501 (Orient)

Carabus variegatus Fabricius, 1792: 147 (Orient)

Graphipterus serrator lobatus Alfieri, 1976: 15 [unavailable name]

Graphipterus serrator sexguttatus Alfieri, 1976: 15 [unavailable name]

Type material of Carabus serrator .

Holotype: ♀ (White label with blue margin, black handwritten): <Graphipterus Latr./serrator Forsk./Aegypten>. Deposited in ZMUC [examined].

Type material of Carabus variegatus .

Holotype: gender unknown (only fragments of a beetle preserved). (White label with black margin, black handwritten): <variegatus/ 824>. Deposited in ZMK [examined] (Fig. 28d).

Diagnosis.

Large species with 10-12 isolated white round spots on elytra: anterior and posterior discal spots larger than other spots, six smaller spots near suture form circular pattern on disc; four white marginal extensions present, extension I triangular. Median lobe of aedeagus with ventrally bent tip.

Comparisons.

Graphipterus serrator resembles G. valdanii from which it differs mainly by the following characters: G. serrator : mentum with three teeth, mid tooth shallow; PL/PW (0.72); BPW/HW (0.8); EL/EW rounded (1.18); elytra lateral margin wide as antennomere I long; Claws of hind legs dark. G. valdanii : mentum with three teeth, merges shallow and mid tooth bolt; PL/PW (0.64); BPW/HW (1); EL/EW elongated (1.3); elytra lateral margin wide as half antennomere I long; Claws of hind legs brown.

Description.

BL male: 17-18 mm, average 17.6 ± 0.4 mm; BL female: 17.4-21.4 mm, average 19.3 ± 2 mm.

Head medium; HW/PW: 0.76; EYL: 1.6-1.8.0 mm; EYL/EL: 0.16. Mentum with three teeth, mid tooth shallow (Fig. 3f). Frontal ridge absent. In male, Apical white frons stripes slenderer than exposed frons (Fig. 4b). Pronotum wide; PL/PW: 0.58; BPW/PW: 0.65; posteromedially concave and without white margins; white lateral margin as wide as antennomere I long.

Elytra oval, humeri rounded; EL: 9.3-11.3 mm, average 10.3 mm; EW: 7.0-9.8 mm, average 8.4 mm; EL/EW: 1.2. Lateral cross section convex. Elytra with dense black scales, disc of elytra not visible between scales (Fig. 6a). White lateral margin nearly as wide as antennomere I long and with four extensions; extension I triangular with rounded angels, margin of elytra wider and shorter than extension II; the latter one elongated; at third quarter of elytra, imaginary line connecting the medial ends of the extension I and I parallel to the suture. White posterior margin forming gap at suture which is wider than lateral margin. Disc usually with 10, sometimes 12 round spots; anterior pair of spots circular to slightly elongate, narrower than extension I, larger than the six central spots forming a circular pattern; anterior and posterior pair of spots circular rounded, larger than other spots; small additional spots frequently present laterally to the posterior spots. Apical sinuation strongly developed, apex protruded, almost rectangular, only slightly rounded at most distant tip (Fig. 7a). Suture inconspicuous.

Legs long; MTIL: 4.8-7.4 mm, average 6.1 mm; El/MTIL: 1.7. Metatibial secondary spur dark. MTAL: 4.0-5.3 mm, average 4.6 mm; MTAL/MTIL: 0.8. Claws of hind legs black at base. Median lobe of aedeagus with ventrally bent tip (Fig. 9m).

Habitat.

Very common in arid sandy habitats, it shows a significant habitat preference for the crest of shifting sand dunes (Fig. 14). It avoids stabilized interdunes and half-stabilized dune slopes ( Renan et al. 2011). The sandy habitat in the western Negev sand dunes is poor in perennial woody plants with maximal coverage of 10-15% ( Perry 2008; Siegal et al. 2013). The dominant perennial plants are Retama raetam ( Fabaceae ) and Stipagrostis scoparia ( Poaceae ).

Co-occurring species.

Graphipterus serrator lives in sympatry with G. multiguttatus in Egypt and Israel.

Distribution.

North-east Egypt (incl. Sinai) and Israel. In Israel it is restricted to the western Negev sand dunes (Fig. 19).

Conservation.

The sand dunes in the western Negev suffer from two major threats: agricultural development that has caused a significant loss of the sands’ range ( Ben David and Avni 2013), and a stabilizing process of the shifting sand resulting from a bio-crust (Kidron and Abeliovich 2009). In the Sinai Peninsula, a lack of shrubs as a result of overgrazing threats the population.

Comments.

The female holotype of Carabus serrator has been considered lost ( Basilewsky 1977), but it was recently found by us in ZMUC (Fig. 28 b–c). After studying the type material, we agree with Hůrka (2003), Lorenz (2005) and Huber and Marggi (2017), that variegatus ( Fabricius 1792) falls within the morphological variability of serrator. Therefore variegatus is confirmed as a junior synonym of serrator (Fig. 28d). Graphipterus serrator lobatus and G. serrator sexmaculatus were considered by Alfieri (1976) as variations of G. serrator . Following the ICZN (1999, Article 45.6.3), a taxon that is described as a variation after 1960 is not valid. Moreover, no holotype has been designated. Therefore, both lobatus Alfieri and sexmaculatus Alfieri are not available names. One specimen from the western Negev sands was found with intermediate characters of G. serrator serrator and G. multiguttatus , and this specimen seems to be a hybrid between them: ♂ Israel, Holot Agur, May 2012, leg. I. Renan.

Biology.

Adults emerge immediately after the first significant rainfall and inhabit sandy dunes or sand and loess plains and edges of salt lakes. In the spring following an average rainy winter, the species can densely populate the dunes (one observer can locate up to 40 individuals within one hour). Their diet is based mainly on ants and occasionally on other small insects, as well as on dead insects and dead reptiles. Activity is limited by temperature: it begins at a soil temperature of approximetly 18 °C, and ceases at a soil temperature of approximetly 39 °C. By moving between sun-exposed microhabitats and the shadow of dwarf-shrubs can prolong the activity period. Strong wind halts activity due to the beetle's sensitivity to dehydration. Some activity also occurs in the afternoon, but it is significantly lower than in the morning peak hours.

Prior to commencing inactivity, the beetle digs a short burrow with a narrow elliptic cross-section into the dune’s slope. The digging is performed mainly with the hind legs and secondarily with the middle legs. The well-developed, spoon-shaped metatibial spurs (see fig. 4a in Assmann et al. 2015) seem to function as a shovel. The burrow’s opening usually collapses behind the beetle or is covered by shifting sand. In the burrow, a few centimeters below the sand surface, the beetle is relatively protected from predation and can probably still detect the outside temperature and light conditions. In enclosure experiments with individual markings and variation in population density, one of us found that even during the peak activity season, most of the specimens spend most of the days without displaying epigeic activity. An encounter between two individuals of any gender immediately develops into a short, hasty, bite battle and the escape of the loser. In some regions, shade is a limited resource and the battle occurs mainly under bushes and dwarf-shrubs. An encounter between male and female starts with an aggressive fight. The persistent male will then mount the back of the female. His forelegs grasp the female between the basal part of the pronotum and the elytral humeri, while the female tries to grab the male with her hind legs. The copulation lasts for approximately 30 minutes and occurs mostly beneath perennial vegetation. During the fight, the beetles stridulate. This sound is produced when the beetles are threatened by other individuals or by potential predators (Renan unpublished data, based on field observations and arena experiments).

Scraping record.

Comparing G. serrator 's scraping spectrograms with those from its co-occurring species, G. multiguttatus , reveals clear differences in pulse intervals as well as in the sound pressure level (Fig. 10).