Tetramorium diomedeum Emery, 1908

Csősz, Sándor & Schulz, Andreas, 2010, A taxonomic review of the Palaearctic Tetramorium ferox species-complex (Hymenoptera, Formicidae), Zootaxa 2401, pp. 1-29 : 17-20

Tetramorium diomedeum Emery, 1908

Tetramorium caespitum var. diomedea Emery, 1908: 24 . Subspecies of ferox: Grandi, 1935: 102 . Junior synonym of ferox: Bernard, 1967: 235 . Raised to species: Schembri & Collingwood, 1981: 435. Revived status as species: Sanetra, Güsten & Schulz, 1999: 324. Syntype workers, gynes, males (9w, 6q, 1m): Italy, Tremiti, Caproni (J. Domino Cecioni) [labels: Tremiti, caproni; T. caespitum , ferox , var. diomedea n.] (examined) [MSNG].

Tetramorium caespitum subsp. ferox var. laevior Forel, 1911: 333 . Unavailable name.

Tetramorium ferox var. laevior Menozzi, 1936: 292 . First available use of Tetramorium caespitum subsp. ferox var. laevior Forel, 1911: 333 . Syntype workers (6w): Turkey, Bosphorus (Forel) [labels: Typus; T. caespitum L., r. ferox Ruzsky , v. laevior Forel , type, Bou Youk Déré, Bosph. Eur. (Forel); coll. Forel] (examined) [MHNG]. New synonymy.

Tetramorium caespitum var. bariensis Forel, 1911: 331 . Junior synonym of diomedeum: Emery, 1916: 194 . [type locality: Italy, Bari, Apulie] (Not in MHNG, MSNG, not examined).

Description of workers (figs 32–34). Small to large size, CS 753 [647, 930]. Whole body and appendages yellow to brown. Head slightly longer than broad, CL/CW 1.02 [0.97, 1.08], with feebly convex sides, straight posterior margin with widely rounded corners. Eyes small, or medium sized, EYE 0.165 [0.144, 0.185]. Frons moderately wide, FR/CS 0.38 [0.35, 0.41], frontal lobes usually as wide as the frons, rarely slightly broader, FL/FR 1.0 [1.00, 1.04]. Scape moderately long, SL/CS 0.76 [0.73, 0.79], without a dorsal-basal carina, surface smooth and shiny. Promesonotal dorsum slightly convex, metanotal groove shallow. Propodeal denticles moderately long. Petiolar node trapezoid seen in profile, higher than long NOH/NOL 1.12 [0.96, 1.39].

Head longitudinally rugulose and feebly microreticulate, in eastern populations rarely the head can be shiny, posterior surface reticulate, ground surface very feebly microreticulate, appears shiny.Mesosoma dorsum and mesopleura finely ruguloso-reticulate, ground surface feebly microreticulate, or smooth. Dorsolateral part of petiolar node ruguloso-reticulate, ground surface microreticulate, median part smooth. Dorsum of postpetiole rugulose and microreticulate. First gastral tergite smooth, appears shiny. Ventral surface of head with a row of short setae only (without long C-shape hairs).

Description of gynes (figs 29–31). Medium size, CS 955 [857, 1012]. Head distinctly broader than long, CL/CW 0.88 [0.85, 0.93], with straight, sub-parallel sides, straight posterior margin with widely rounded corners. Frons wide, FR/CS 0.42 [0.39, 0.46]. Scape short to moderately long, SL/CS 0.72 [0.67, 0.76]. Head as wide as scutum, MW/CS 1.01 [0.92, 1.12]. Propodeal denticles short. Petiole and postpetiole wide, CS/ PEW 1.68 [1.53, 2.09], CS/PPW 1.33 [1.24, 1.42].

Whole body and appendages yellow to brown. Frons and genae with very fine longitudinal rugulae, or completely smooth, rest of head smooth. Scutum, scutellum, and anepisternum smooth and shiny, very fine rugulae can occure, ventral part of katepisternum always smooth and shiny. Petiolar node and postpetiole feebly microreticulate, or smooth and shiny. First gastral tergite smooth, appears shiny. Ventral surface of head with a row of short setae only, without long C-shape hairs.

Description of males. Head sides feebly convex, posterior margin widely rounded. Scutum much broader than head. Propodeal denticles reduced, propodeum rounded in profile. Dorsum of petiolar node without a transverse crest, dorsolaterally sharp and angulate. Whole body and appendages brownish black. Head finely rugulo-reticulate, between main sculpturation microreticulate. Scutum, scutellum, anepi- and katepisternum finely rugulose, and smooth in part. Petiole and postpetiole finely rugulo-reticulate, between main sculpturation microreticulate.

Diagnosis. In general the smooth and shiny sculpture separates T. diomedeum gynes from those of T. ferox and T. densopilosum . Ventral part of katepisternum is always smooth and shiny in T. diomedeum gynes. These characters can also help to distinguish them from the gynes of T. ferox , where the kataepisternum is always finely rugulose or microreticulate. Gynes of T. diomedeum can be confused with those of T. feroxoide by the feeble sculpture of head and mesosoma. However, gynes and workers of T. feroxoide have long C-haped setae on the ventral surface of head. Those of T. diomedeum have only short setae on the ventral surface of head. The colour can also be a good characteristic for the separation between the gynes of the latter two species: T. diomedeum is light brown or sometimes (though not frequently) yellow. The gynes of T. feroxoide are usually dark brown or black.

Tetramorium diomedeum workers cannot be confused with those of T. ferox or T. densopilosum . The general appearance of the head of T. diomedeum workers are always shiny, and usually smooth at least in part, these body parts of T. ferox or T. densopilosum are rugulose and microreticulate.

In a few cases larger T. diomedeum workers can be confused with those of T. feroxoide by sculpture. However, in the eastern populations (in Turkey where these two species co-occur) sculpture of diomedeum workers is usually very feeble. These characters and the lack of C-shaped setae of T. diomedeum workers (in contrast to those of T. feroxoide ) result in clear separation without morphometry. In order to achieve the best separation for the doubtful cases of T. diomedeum and T. feroxoide workers we provide the discriminant function D(7) = 0.0604 CL –0.0398 FR -0.0578 SL -0.0697 NOH +0.0346 SPSP -0.0398 EL +0.0402 POC - 1.0136. This analysis resulted in 98.6% success, with four erroneously identified cases of the 276 individuals, while 100% of the nest samples were correctly classified. The mean D(7) scores for T. feroxoide workers (n=48) was -1.980 1.11 [-4.021, -0.381], for nest means (n=8) -2.493 1.13 [-3.487, -0.739]. The mean scores for T. diomedeum workers (n=228) was +1.980 ±0.97 [-0.550, +4.975], for nest mean (n=42) +2,090±0.75 [+0.391, +4.161].

Workers of T. diomedeum can also be confused with those of T. aegeum on the basis of external characters. The sculpture of these species is similar to each other; head and mesosoma are frequently smooth and shiny. For best separation a discriminant D(4a) function has been provided (see differential diagnosis of T. aegeum ).

For the results of cumulative discriminant analysis for worker caste see Tables 3 & 4 and for gynes see Tables 5 & 6 . Morphometric characters and indices for workers and gynes are provided in Table 7 & 8.

Distribution. Eastern part of the Mediterranean basin: Italy, Croatia, Bulgaria, Turkey and Greece – including the islands of Rhodos and Crete.

Geographic variation. Along the wide, decisively east–west geographical range, including small islands, workers of T. diomedeum display a rather strong gradient of morphological variation in characters such as body size, colour and sculpture. Body size indicators (CS) of individuals show moderate correlation with longitude (Spearman r = -0.391, p<0.01), i.e. eastern populations are smaller. Average CS values of nest means do not correlate significantly (Spearman r = -0.304, p=0.06).

In the eastern populations workers are paler, body sculpture feebler, and the post-ocular surface of head in particular is smooth and shiny. Smaller workers often bear one pair of standing hairs on genae. This combination of characters is more frequent in the eastern populations and rare in the western ones. Some workers in nest series from Calabria and Syracusa ( Italy) also bear this combination of characters, especially in the case of small workers.

Material examined. BULGARIA—Achtopol, 0 7.10.0 5.1958 leg Pisarski (5 w / HNHM);

CROATIA—Karlobag 0 1.10.2004 leg. Csősz, nr. CRO 0 62 (10w / HNHM);

GREECE—Crete, Prov. Herakleion 2km N Zaros 400–500mH. 25.04.1992. leg. Sanetra (5w / MSNM); I. Rodi 0 6.1997. „AT 1.1” (3w, 1q / NMSM); Kreta 1 km NW Melambes 600–700 m Nordostseite Wiese 24.– 04.05.1992.leg.Schulz nr. 624. (3w / PCAS); Kreta 1 km S Anisraki nahe Kandanos Wiese 700 m, 24.– 0 4.05.1992. leg. Schulz nr.696. (2w / PCAS); Kreta 3 km SWW Omalos 1400–1600 m Nordwesthang Eichenwald, 24. – 04.05.1992. leg. Schulz nr. 684. (6w / PCAS); Kreta l km S Anisraki nahe Kandanos Eichenhecke 700 m, 24.– 04.05.1992. leg. Schulz nr. 696. (2w / PCAS); Kreta, Zaros Bachschlucht 400 m Kiefernwald, 24.– 04.05.1992. leg.Schulz nr. 635. (3w / PCAS); Peloponnes, Prov Lakonia, Oros Taigetos, 20 km SW Sparti, 36°58'N, 22°21'E, 1800–2100 m, 29.04.2000. leg. A.Schulz nr.150. (5w / PCAS); Peloponnes, Prov. Arkadia, Parnon, 10 km SWS Kosmas, 37°04'N, 22°43'E, 800 m, 26.04.2000. leg. A.Schulz nr. 87. (5w / PCAS); Peloponnisos 28 km NW Tripolis, Pass zw Vitina u Karakaloú, 1140mH, 0 6.1994. leg. Schulz, Vock nr. 1391. (3w / PCAS); Rhodos 5 km E, Agios Isidoros, 36°12'N, 27°50'E, 600mH, 17.03.2002. leg. A.Schulz nr. 37. (6w / PCAS); Rhodos 5 km E, Kattavia, 35°57'N, 27°49'E, 50mH, 21.03.2002. leg. A.Schulz nr.116. (6w / PCAS); Rhodos 6 km N Kalathos 36°12'N, 28°07'E 50mH, 19.03.2002. leg. A.Schulz nr. 60. (5w / PCAS); Rhodos, 5 km E Kattavia, 35°57'N, 27°49'E, 50mH, 21.03.2002. leg. A.Schulz nr. 111. (6w / PCAS); Rhodos, vic. Lindos und Stadt, 36°06'N, 28°05'E, 20–50mH, 17.– 23.03.2002. leg.A.Schulz nr. 98. (9w, 1 q / PCAS);

ITALY—Calabria, Prov. Catanzaro 3 km E Savelli, 700mH, 19.05.1994. leg. Schulz, Gusten, Sanetra nr. 1299. (3w / PCAS); Calabria, Prov.Catanzaro, 3 km E Savelli, 700mH, 19.05.1994. leg. Schulz, Gusten, Sanetra nr.1301. (1q / PCAS); Calabria, Prov. Catanzaro, 3 km NW Umbriatico, 350mH, 19.05.1994. leg. Schulz, Gusten, Sanetra nr.1305. (1m / PCAS); Calabria, Prov. Cosenza, 4 km N Morano Calabro, 800mH 21.05.1994. leg. Gusten, Sanetra nr.T. 351. (3w, 3 q, 5m / PCAS); Calabria, Prov. Cosenza, 4 km N Morano Calabro, 800mH, 21.05.1994. leg. Gusten, Sanetra nr. 381. (3w / PCAS); Calabria, Sambiase 0 4.1926 leg Minozzi (sic) (5w, 1q / ZMPA); Campana, Prov. Napoli Monte Faito, 5rkm NW Moiano, 800–1000mH, 24.09.1997. leg. M.Sanetra, A.Buschinger, R.Schumann nr. T.763-12. (6w / PCAS); Nicolosi, CT. 600mH, 10.10.1953 leg. Anonym (5w / MSNM); Puglie, Leuca 1975. leg. Springhetti (2w / MSNM); Sicilia, Edlie, Filicudi 0 6.04.1990. leg. Mei (8w / MSNM); Sicilia, Prov. Catania, Etna, 5 km N Ragalna 1000–1200mH, 12.05.1994. leg. M. Sanetra nr. Td.317. (3w / PCAS); Sicilia, Prov. Syrakus, 5 km NE Canicattini Bagni 300mH, 11.05.1994. leg. M. Sanetra nr. 379. (2q / PCAS); Sicilia, Prov. Syrakus, 5 km NE Floridia 100mH, 11.05.1994. leg. M. Sanetra nr. T.307. (3w / PCAS); Sicilia, Prov. Syrakus, 5 km NE Floridia, 100mH 11.05.1994. leg. M. Sanetra nr. T.308. (3w / PCAS); Sizilien, Prov. Syrakus, ca 5 km NE, Canicattini Bagni, 300mH, 29.05.1993. leg. M. Sanetra (3w / PCAS);

TURKEY—Antalya 25 km SW Elmali 90 km E Fethiye, bei Gömbe 1500mH Wiesengelände mit Bäumen, 23.05.1993. leg. Schulz nr. 907. (3w / PCAS); Antalya 5 km E Saklikent, 35 km W Antalya 1500– 1700mH Kiefernwald und Wiese 28.05.1993. leg. Schulz nr. 936. (6w / PCAS); Prov. Mersin, Aydincik 7 km E, 50 km E Anamur, 200–400mH, 15.05.1997. leg. A. Schulz nr. 357-39 (3w / PCAS); Prov. Antalya, Demirtas 14 rkm NE, 400mH 0 4.05.1997. leg. A. Schulz, K. Vock, M. Sanetra nr. T.699-06. (3w / PCAS); Prov.Antalya, Demirtas 2 rkm N, 100mH, 0 4.05.1997. leg. A. Schulz, K. Vock, M. Sanetra nr. T.699-05. (3w, 6q / PCAS); Prov. Kayseri, Incesu 2 rkm NE, 30 km SW Kayseri, 1100mH, 10.05.1997. leg. A. Schulz, K. Vock, M. Sanetra nr. T.697. (3w / PCAS); Prov.Kayseri, Incesu 2 rkm NE, 30 km SW Kayseri, 1100mH, 10.05.1997. leg. A. Schulz, K. Vock, M. Sanetra nr. 267-27. (24w, 1q / PCAS); Mugla- 10 km NNE Kemer 30 km NEE Fethiye 1000mH Kiefernwald, 22.05.1993. leg.Schulz nr.904. (6w / PCAS); Mugla- Dirimli Gecidi, 100 km W Antalya, 30 km SSE Gölhiser 1600mH Kiefernwald, 22.05.1993. leg.Schulz nr.904. (3w / PCAS); NE Incesu 2rkm, 30 km SW Kayseri, Prov.Kayseri, 1100mH, 10.05.1997.leg.A.Schulz, K.Vock, M.Sanetra nr. T.696-27 (6w / PCAS); Nur Daglari 7-10rkm, Prov.Antalya W Hassa 1000–1200mH, 11.– 12.05.1997. leg.A.Schulz, K.Vock, M.Sanetra nr. 312-33 (9w / PCAS); Nurdagi Gecidi, 20 km N Islahiye, Prov.Gaziantep, (ca. 70 km W Gaziantep), 1200mH 12.05.1997. leg.A.Schulz, K.Vock, M.Sanetra nr.225-34, (12w / PCAS);