Strangulotilla dioscoridea, Cascio & Romano & Grita, 2012

Cascio, Pietro Lo, Romano, Marcello & Grita, Flavia, 2012, New species and new records of mutillid wasps from the Socotra Archipelago (Hymenoptera: Mutillidae), Acta Entomologica Musei Nationalis Pragae 52, pp. 525-544 : 529-532

Strangulotilla dioscoridea sp. nov.

( Figs. 1–2 )

Type locality. YEMEN, Socotra Island, Di Hamri, 12°37′59″N, 54°15′40″E.

Type material. HOLOTYPE: ♀ ( NMPC), ‘ Socotra Island: NW, Di Hamri , 20 m a.s.l. / N 12°37′59″ – E 54°15′40″ / 27.ii.2010, L. Purchart leg. ’. PARATYPE: ♀, ‘Samha Island:W[est] / N 12°09′ – E 52°59′ / 23-24.ii.2008 / A. Saldaitis leg.’ ( MRCI).

Diagnosis. A female of Strangulotilla mainly characterized by a median hourglass-shaped belt of white sparse pubescence on T2 and by a weakly striated pygidial area.

Holotype description. Body length: 7.1 mm. Habitus as in Fig. 2 . Head pale red, subrectangular, 1.24 broader than long and 1.15 wider than pronotum, with rounded posterior angles, slightly depressed in occipital area. Surface densely punctate, with punctuation large and shallow, but smaller on frons and completely lacking on frontal carina, which gives head vaguely rugulose appearance. Eyes oval, moderately convex, slightly protruding from profile of head; maximum orbital diameter 0.6 of interocular distance; ratio between maximum and minimum orbital diameter 1: 0.53. Clypeus arcuate and slightly prominent, with small, shiny basal median tubercle and two small protruded and darkened tubercles at ends of clypeal carina. Mandibles ferruginous, curved, with prominent tooth on inner margin at basal third, then narrower and darkish in apical third. Antennae entirely pale reddish, with scape slightly curved; ratio between scape, pedicel and F1 is 1: 0.23: 0.38.

Mesosoma pale red, 1.09 longer than broad, slightly enlarged in anterior third, broader in posterior one; pronotum moderately arched, with obtuse anterior angles; lateral margins indefinably jagged, with concave profile; on basal margin row of five prominent denticles above propodeal declivity, median ones longer than lateral; posterior angles feebly rounded. Surface moderately rugulose, irregularly and densely punctate, with punctuation larger than that of head. Scutellar scale indistinct; metanotal carina consisting of just two weak furrows converging backwards but not connected to each other, where mesosoma is enlarged posteriorly. Pleurae weakly concave, with smooth and shiny surface; upper margin of mesopleurae marked by darkish suture. Propodeum strongly truncated, with shiny surface; angle between propodeal and dorsal surface of mesosoma is 95°.

Legs entirely pale red, except calcaria and spurs which are white, without salient characteristics.

Metasoma black except for T1 which is slightly reddish on its anterior face, 1.32 broader than mesosoma in its maximum width; T1 as broad as hind width of mesosoma. T2 dorsally with fine and shallow punctuation, which laterally becomes more spaced and foveolate. Pygidial area weakly striated, with impressions arranged in herring-bone pattern coming down from inner to outer upper half, and horizontally disposed in lower half ( Fig. 3 ).

Pubescence on head whitish, sparse and recumbent, backward facing, except on genae where it is forward facing; few scattered erect, long setae close to eye margin; dense erect, long setae on occipital side. Short and yellowish erect setae occur on clypeus and on basal half of mandibles, as well as on scapes, while all following flagellomeres are finely covered by very short pubescence. Mesosoma dorsally covered by whitish, sparse and recumbent setae; scattered erect setae, mainly whitish but mixed with reddish ones, occur along anterior and lateral margins. Very short and almost evanescent pubescence sparsely covers the meso- and metapleuron surface. T1 with erect and long whitish setae, densely distributed on anterior side, toward propodeum, and black sparse setae covering surface, except for whitish fringe on posterior margin; T2 dorsally and laterally covered by recumbent black setae mixed with few scattered, erect whitish setae on sides, and crossed by median hourglass-shaped belt of white sparse pubescence starting from T1 fringe and merging in T2 basal fringe; T3 almost entirely covered by whitish pubescent belt; T4 and T5 covered by sparse and black pubescence and with scattered erect whitish setae, which occur also around pygidial area. Felt lines whitish and barely visible; distance from basal margin 1.37 longer than their distance from posterior margin of T2.

Male. Unknown.

Variability. The paratype from Samha Island is slightly reddish, stronger and longer (length: 7.6 mm) than the holotype, with head 1.37 broader than long and 1.16 wider than pronotum, mesosoma as broad as long, seven denticles irregularly spaced on epinotal row, more dense pubescence on head and mesosoma, more abundant sparse recumbent pubescence on T2. Maximum orbital diameter 0.5 of interocular distance, and ratio between maximum and minimum orbital diameter 1: 0.57; ratio between scape, pedicel and first flagellomere 1: 0.21: 0.39.

Differential diagnosis. According to NONVEILLER (1979), Strangulotilla is distinguished from the closely related genera Ctenotilla Bischoff, 1920 , Cephalotilla Bischoff, 1920 , and Chaetomutilla Nonveiller, 1979 by having the pygidial plate not sculptured, and from Montanomutilla Nonveiller, 1979 , which is characterized by the mesosoma strongly restricted anteriorly by the propodeum. Surface of the pygidial plate in Strangulotilla is smooth or finely shagreened, with the only exception of S. bechuana ( Hesse, 1935) from Botswana, where the basal half is covered by little-pronounced striae. The striated feature of the pygidial plate of S. dioscoridea sp. nov. therefore excludes any possibility of this species being identical to any other species of this genus; at the same time, its occurrence exclusively in this species and S. bechuana represents the only morphological character which suggests a certain affinity among them within the genus. Although the type of S. bechuana has not been examined by us, we compared our material with two female specimens of this species respectively kept at IMCT (labelled ‘Mr Stone / Bechuanaland [beneath] May-June / 1930’ ‘ Strangulotilla / bechuana / det. Nonvll. 1978’; images of this specimen are available at: www.waspweb.org) and at BMNH (labelled ‘L. Ngami / 12 mls NE Sehitwa / 16/ 17-IV-1972 ’ ‘Southern Africa / Exp. B. M. 1972 – I’ ‘ Strangulotilla / bechuana / det. Nonvll. 1978’). Also according to the descriptions given by HESSE (1935: 517, fig. 4, sub Ctenotilla ) and by NONVEILLER (1979: 56, fig. 5c), S. bechuana remarkably differs from the new species by having metasoma pale reddish except for a narrow black basal belt on T2, head 1.3 wider than pronotum, ratio between maximum and minimum orbital diameter 1: 0.73, T1 narrower than hind margin of mesosoma and T2 significantly wider than T1, different pattern of pubescence on T2 and striae pattern on pygidial plate and, finally, small size. Another species, S. samharica ( Magretti, 1906) , has been recently recorded for continental Yemen ( LELEJ & HARTEN 2006), but it can be easily distinguished from S. dioscoridea sp. nov. due to smooth pygidial area, different pattern of pubescence on T2, as well as entirely black head; NONVEILLER (1979: 52) assigned to this species the form clariceps, described based on a female from Sudan and characterized by reddish head, however, resembling the nominal form in all the above mentioned characters. Etymology. The species epithet is intended to recall one of the ancient names of Socotra, Dioscorida, mentioned in the Historia Naturalis by Pliny the Elder and in the Periplus Mari Erythraei by Anonymous (both dating to the 1 st century A.D.).

Biological notes. Data from the labels indicated the occurrence of Strangulotilla dioscoridea sp. nov. in arid coastal areas of the islands of Socotra and Samha, both characterized by sandy-rocky mixed substrate and covered by sparse dwarf scrubland. Other traits of its biology are still unknown.

Zoogeographical notes. The genus Strangulotilla currently includes one species from Sri Lanka ( LELEJ 2005) and seventeen species from Africa ( NONVEILLER 1979), some of them previously assigned to Ctenotilla , Mutilla Linnaeus, 1758 or Smicromyrme Thomson, 1870 (see ANDRÉ 1902, 1905; MAGRETTI 1906; CAMERON 1908; BISCHOFF 1920, 1921; BRADLEY & BEQUAERT 1928; HESSE 1935). Most part of these species occurs in the Ethiopian realm, including the Cape subregion; among them, S. samharica ( Magretti, 1906) , also recorded for continental Yemen ( LELEJ & HARTEN 2006), was considered as a vicariant of the widely distributed S. thoracosulcata ( Magretti, 1906) in the arid Eastern African areas by NONVEILLER (1979). Although the phylogenetic relationships within this genus need to be clarified, the occurrence of a Strangulotilla that is supposedly related to African species in the Socotra Archipelago can be explained by palaeogeographic data that show that these islands definitively detached from Africa about six million years ago ( BEYDOUN & BICHAN 1970, FLEITMANN et al. 2004); moreover, the so far known distribution of S. dioscoridea sp. nov. suggests that i) the species is probably endemic to the archipelago, ii) that land connections between Samha and Socotra, that occurred during the Last Glacial Maximum (about 18,000 years ago: see FLEITMANN et al. 2004, DAMME 2006), undoubtedly contributed to the present distribution pattern. Insular endemics, such as Strangulotilla minor ( André, 1905) from São Tomé Island (Gulf of Guinea, W Africa), and S. krombeini Lelej, 2005 from Sri Lanka ( NONVEILLER 1979, LELEJ 2005), are already known within this genus.

Figures

Fig. 1. Sites of collection of the examined material at Socotra Island. Toponyms follow WRANIK (2003) and MILLER & MORRIS (2004) and are progressively numbered from East to West. Samha Island is not indicated in the map. 1 – Homhil; 2 – Di Hamri; 3 – Wadi Kam; 4 – Rokeb (S of Di Hamri); 5 – Di Ishal; 6 – Wadi Di-Fa’rhoh; 7 – Di Zumhum; 8 – Haggeher; 9 – Diksam plateau (Firmihin); 10 – Wadi Da’arho; 11 – hills near Hadibu; 12 – Wadi Ayheft; 13 – Diksam canyon; 14 – Wadi Zerig; 15 – Quadheb; 16 – unnamed place 30 km East from Qalansiyah; 17 – Qa’arah; 18 – Detwa lagoon; 19 – Qalansiyah.

Figs. 2–4. Socotran Mutillidae. 2–3 – Strangulotilla dioscoridea sp. nov.: 2 – habitus of holotype (a – dorsal view, b – lateral view, scale bar = 1 mm), 3 – pygidial plate of the holotype (scale bar = 200 μm). 4–5 – Macromyrme bezdeki sp. nov.: 4 – habitus of the holotype (a – dorsal view, b – lateral view, scale bar = 1 mm), 5 – pygidial plate of the holotype (scale bar = 300 μm).