Deretus denticollis Gahan 1900
Creators: name: Purchart, Luboš
Publisher: name: Zenodo
Year: 2012
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Coleoptera
Tenebrionidae
Deretus
Deretus denticollis

description: Deretus denticollis Gahan, 1900
(Fig. 3, 4, 14, 20, 25)
Deretus denticollis Gahan, 1900: 10.— Gebien 1942: 902 [817]; Koch 1970: 124 –127 (with figure of habitus) (partim). Deretus denticollis: Gahan 1903: 281 –282 (redescription, with figure of habitus).
Deretus wraniki Schawaller, 2004: 457 (with figure of habitus) syn. nov.
(see also Deretus necopinatus sp. nov. and D. maderai sp. nov.)
Type locality. Yemen, Socotra Island, Jena-agahan.
Type material examined. Deretus denticollis: Lectotype (designated here)—(Ƥ BMNH): Type {white and red, rounded, printed} // Jena-agahan, Sokotra. 1200 feet, Jan. 99, W.R.O. Grant, 99-85 {white, printed} // Deretus denticollis Gahan, Type {white, handwritten}.
Deretus wraniki: Holotype —(13 SMNS): ZOOLOGISCHE EXKURSION, Socotra, Diksam, 11. 1997, leg. Wranik {white label, handwritten}// HOLOTYPUS, Deretus wraniki n. sp., Schawaller 2000 {red label, printed}; Paratype [actually D. maderai sp. n.]– (1Ƥ SBSC): YEMEN E, Socotra Isl., 6.–24.ix.1999, V.Bejček & K.Šťastný lgt. {printed}// COLLECTION STANISLAV BEČVÁŘ {yellow, printed} // PARATYPUS, Deretus wraniki n.sp., SCHAWALLER 2000 {red, printed}.
Additional material. (43+ 4Ƥ LPCB): Yemen, Socotra Island, wadi Ayhaft, 12°36.5’N, 53°58.9’E, 200 m, 7– 8.xi.2010, L. Purchart lgt.; (43+6Ƥ LPCB): same data as previous, but J. Bezdĕk lgt.; (1Ƥ JBCP): same data as previous, but Jan Batelka leg.; (53+4Ƥ NMPC): same data as previous, but Jiří Hájek leg.; (13 LPCB): same data as previous, but J. Bezdĕk lgt., Alcohol 70 % + acetic acid; (1Ƥ SBCB): Yemen, Socotra Isl., Hadiboh env., 6.– 24.1999, V.Bejček & K.Šťastný lgt.; (13 SBCB): Socotra Isl. (Yemen), Hamadero, 20.–21. xi. 2000, lgt. V. Bejček + K. Šťastný; (13 SBCB): Socotra Isl. (Yemen), Ayhaft, 3. xi. 2000, lgt. V. Bejček + K. Šťastný; (23 SBCB): Socotra Isl. (Yemen), Lahas, 17.–18. xi. 2000, lgt. V. Bejček + K. Šťastný; (23+ 2Ƥ NMPC): Yemen, Soqotra Is., 21.xi.–12.xii.2003, Hadiboh env., ca 10–100 m, N 12°65’02’’ E 54°02’04’’ [GPS], David Král lgt.// Yemen – Soqotra, 2003, Expedition; Jan Farkač, Petr Kabátek & David Král; (23+ 4Ƥ NMPC): Yemen, Soqotra Is., 24– 26.xi.2003, wadi Ayhaft, 190 m, N12°36’38” E53°58’49” [GPS], David Král lgt. // Yemen – Soqotra, 2003, Expedition; Jan Farkač, Petr Kabátek & David Král; (13 JFCP): same as previous, but Jan Farkač lgt.; (13 NMPC): Yemen, Soqotra Is., Homhil protected area, 28–29.xi. 2003, 364 m, N12°34’27” E54°18’32” [GPS], David Král lgt. // Yemen – Soqotra, 2003, Expedition; Jan Farkač, Petr Kabátek & David Král; (33 JFCP): same as previous, but Jan Farkač lgt.; (1Ƥ JFCP): Yemen, Soqotra Is., 6.–7.xii.2003, Noged plain: wadi Ireeh, N 12°23’11” E 53°59’47”, 95 m [GPS]; Jan Farkač lgt. // Yemen – Soqotra, 2003, Expedition; Jan Farkač, Petr Kabátek & David Král; (23 NMPC): Yemen, Socotra Island, Aloove area, Hassan vill. env., 12°31.2’N, 54°07.4’E, 221 m, Jiří Hájek leg., 9.– 10.xi.2010; (1 ƤSMNS): Socotra Archipelago, Socotra, Hadibo, 1.xi.2008, leg. T. van Harten; (33+ 1Ƥ SMNS): Socotra Archipelago, Socotra, Wadi Danegan, 90 m, 30.x.2000, leg. T. van Harten; (1Ƥ SMNS): Yemen, Soqotra Archipelago, Soqotra, Noged, Farnihin, Steroh wadi, 12°24’26‘‘ N,54°08‘10‘‘ E, 24. x. 2010, leg. T. van Harten, SOQ 2000/06.
Remarks. D. denticollis was described by Gahan (1900) probably based on a single female, as the only known type is a female deposited in the BMNH. However, Gahan stated neither the number of described specimens nor their deposition. For that reason I designate this specimen as a lectotype.
Koch (1970) made a detailed description of a single male specimen deposited in the Frey collection (Natural History Museum, Basel) and designated it as the allotype of D. denticollis. However, this is not a valid name-bearing type (ICZN 1999: 72A) and therefore it cannot be used as a type specimen. Koch undoubtedly believed that this male belonged to the same species as the above mentioned female type specimen in the BMNH. Much later Schawaller (2004) listed an additional 4 females as D. denticollis that were compared with this non-type male described by Koch. The same author also described Deretus wraniki Schawaller, 2004 which was differentiated from D. denticollis mainly by its very small body size.
During expeditions to Socotra Island the author collected, with his colleagues, a larger series of Deretus specimens comprising males and females of several species. These specimens were compared with the type material of D. denticollis and D. wraniki and the non-type male of D. denticollis from the Frey collection. The author discovered that the male holotype of D. wraniki is identical to the lectotype of D. denticollis and therefore D. wraniki should be synonymised. He also observed, based on a large series of this species, that the body size of this species is strongly variable and cannot be used for differential diagnoses. The holotype of D. wraniki simply represents one extreme of the body-size range. It was also found that the female paratype of D. wraniki is a different species (see remarks in D. maderai sp. nov.). The most surprising discovery is that all specimens previously identified by Koch and Schawaller as D. denticollis differ from the lectotype (designated in this paper) and from new specimens of D. denticollis collected in the field. These specimens represent a new species, which has been named Deretus necopinatus sp. nov.
Differential diagnosis. The type specimen was redescribed by Gahan (1903) and figured by Koch (1970). For this reason, and as the male and female do not differ significantly from each other in the shape of habitus (in males the apical antennomere is somewhat longer than in females), the description is not repeated here. Size of lectotype 11.0 x 4.0 mm. Variability of size in females—5.7–11.0 x 2.1–4.1 mm; males—4.7–9.5 x 1.8–3.8 mm.
This species, in its general appearance, most resembles D. necopinatus sp. nov. from which it is differentiated by the shiny integument, the broadly rounded pronotal anterior corners (Fig. 14) and by the absence of patchs of sensillae on the abdominal ventrites together with the unmodified metatibia in males. From D. spinicollis and D. bezdeki sp. nov. it can be distinguished mainly by the shape of the pronotum, which in the latter two species is characterized by extremely elongated (extended) anterior corners (Fig. 13, 18). It differs from D. hulai sp. nov. by its smooth, almost glabrous (only ultra-microscopically and very sparsely pubescent), elytra (conspicuously pubescent and sculptured with small tubercles in the latter species). From D. maderai sp. nov. it can be separated by its almost flat pronotum (lateral view) and by its elytra length / pronotum width ratio, that is larger than 2.0. In D. maderai sp. nov. the pronotum is distinctly convex in lateral view and elytra length / pronotum width ratio is less than 1.8.
description: Published as part of Purchart, Luboš, 2012, Biodiversity research of darkling beetles on Socotra Island. Part I. The genus Deretus Gahan, 1900 (Coleoptera: Tenebrionidae), pp. 57-68 in Zootaxa 3153 on pages 60-61, DOI: 10.5281/zenodo.211332