Tapinoma elongatum Seifert, 2026, sp. nov.

Tapinoma elongatum sp. nov. Etymology. The name is given according to the elongated scape, funiculus segments and mesosoma. Type material. • Holotype plus two paratype worker on the same pin labelled “ SPA: 37.00817, -6.50700, 24 m, Station Donana NP- 5.8 km WNW, stabilised sand dune + shrubs, B. Seifert 2026.03. 02 - 1 ” and “ Holotype (top) and paratypes of Tapinoma elongatum Seifert ”; two paratype workers from the holotype sample with identical site label on a second pin; 50 mounted paratype workers from 10 nest samples with different coordinates from the type locality labelled “ ... B. Seifert 2026.03. 02 - 2 ”, “ ... B. Seifert 2026.03. 02 - 3 ”, “ ... B. Seifert 2026.03. 02 - 4 ”, “ ... B. Seifert 2026.03. 02 - 5 ”, “ ... B. Seifert 2026.03. 02 - 7 ”, “ ... B. Seifert 2026.03. 02 - 8 ”, “ ... B. Seifert 2026.03. 02 - 9 ”, “ ... B. Seifert 2026.03. 02 - 10 ”, “ ... B. Seifert 2026.03. 02 - 11 ”, “ ... B. Seifert 2026.03. 02 - 12 ”; 107 paratype workers from all type locality samples stored in 99.8 % undenatured ethanol; depository of all type material SMN Görlitz, with exception of each two mounted workers from the holotype nest in Naturhistorisches Museum Basel and Museo Nacional de Ciencias Naturales Madrid. Material examined. Numeric phenotypical data were taken in 45 nest samples with 112 workers. They all originated from SW Spain. For details, see Suppl. materials 1, 2. Geographic range. So far known from 10 sand dune sites at the Atlantic coast of SW Spain between 6.4°W and 7.1°W (Fig. 5). Fig. 6 shows that all three non-supercolonial species, Tapinoma elongatum sp. nov., T. nigerrimum and T. hispanicum, have a restricted, very regional distribution which is astonishing because their dispersal does not depend on passive anthropogenic transport. A possible reason might be the overwhelming competitive power of the supercolonial species in anthopogenically transformed habitats. Accordingly, these supercolonial species show a much wider range (Fig. 7) and are introduced into areas far away from their natural range. Diagnosis. Worker (Table 1, Figs 8, 9, 10, 11): As a characteristic for any species of the T. nigerrimum complex, T. elongatum sp. nov. is strongly size-polymorhic with the largest workers in mature nests having more than twice the head capsule measurements and about eight times the weight of the smallest workers. There is, furthermore, a strongly negative allometry of the shape variables CL / CW, PoOc / CL, SL / CS, Fu 2 L / CS and EL / CS and a strongly positive allometry of ExOcc / CS, MGr / CS and IFu 2. For details, see the RAV functions given above. All shape ratios given in the description below are, in contrast to those in Table 1, primary ratios without removal of allometric variance and all data are given as arithmetic mean ± standard deviation. On average, large, but size-polymorphic, CS 938 ± 172 µm. Head more elongated than in related species, CL / CW 1.065 ± 0.068. Postocular distance rather small and excavation of hind margin of vertex smaller than in related species with the exception of T. magnum, PoOc / CL 0.382 ± 0.009 and ExOcc / CS 1.66 ± 0.99 %. Depth of anteromedian clypeal excision smaller than in related species, except for T. magnum, ExCly / CS 8.60 ± 0.88 % and ExCly / ExClyW 1.33 ± 0.17. As typical for the T. nigerrimum complex, the posterior, semicircular end of clypeal excision forms a concave plane delimited by a sharp ventral and a less sharp dorsal edge. Sum of pubescence hairs and smaller setae protruding across the margin of clypeal excision including its dorsal edge large, nExCly 12.7 ± 4.4 (Fig. 6). Scape much longer than in related species, SL / CS 1.025 ± 0.054. Second funiculus segment more elongated than in related species, Fu 2 L / CS 15.06 ± 0.49 %, more than twice as long as wide, IFu 2 2.095 ± 0.092 (Fig. 7). Minimum distance of the inner margins of antennal socket rings moderately large, dAN / CS 0.302 ± 0.008. Eye smaller than in T. magnum, EL / CS 0.246 ± 0.015. Metanotal groove deep, MGr / CS 3.91 ± 0.68 %. Mesosoma longer than in related species, ML / CS 1.350 ± 0.027 and MW / CS 0.644 ± 0.020. All body parts including appendages covered by a rather dense pubescence. Setae on dorsal and lateral surfaces of head and mesosoma absent. Long setae are found on all gaster sternites, ventral parts of coxae and anterior clypeus. All body parts blackish-brown. Mandibles, edge of clypeus and sometimes antennal funiculus and tarsi with an orange or reddish colour component. Taxonomic comments. Based on NUMOBAT characters, accurately recorded by high-resolution stereomicroscopy, Tapinoma elongatum sp. nov. is not confusable with any known Tapinoma species worldwide. There is no Tapinoma worldwide outside the T. nigerrimum complex combining such elongated scapes and funiculus segment with large body size and ragged pubescence fringing the clypeal excision. The comparative data given in Table 1 suggest that the most closely-related species should be T. magnum which is nearest in ten RAV - corrected characters, whereas T. darioi is nearest in three, T. ibericum and T. nigerrimum each in only one and T. hispanicum in no character. This hypothesis on close relatedness with T. magnum has to be checked by adequate nuDNA markers. Biology. There is a low risk to call Tapinoma elongatum an endemic of the Southwest Iberian Atlantic coast because it was absent from 577 collecting sites with Tapinoma species in the Palaearctic west of 36°E and, in particular, it was absent from 170 collecting sites with Tapinoma species in Portugal, Spain, Morocco, Algeria and Tunsia. Its only known findings are restricted to coastal sand dune habitats along a shore-line of only 75 km length. Expectably, additional records can be made in dunes further west of the Spanish-Portuguese border, but there the coast-line of Portugal is dominated by steep rocky cliffs. T. elongatum sp. nov. obviously could not penetrate urban or rural areas in South Iberia where T. ibericum is the absolutely dominating species. The highest nest densities of T. elongatum sp. nov. were found in semi-stabilised sand dunes with incomplete herb cover and scattered shrubs. It also occured in short-grassy, more humid cattle and horse pastures with an almost closed field layer and only few patches of bare sand. The lowest densities were found in bare, wind-moved sand dunes in which the nest sites were restricted to small, scattered patches stabilised by vegetation pads. The elongated antennae, leg, and mesosoma of T. elongatum sp. nov. may be an adaption to open habitats with a much barer surface, as this condition potentially allows for a higher foraging velocity. Nest entrances were frequently constructed in the form of crater-like sand ejections as it is typical for the Tapinoma nigerrimum complex. The colony demography is not clear. Most surprisingly, not a single queen individual was observed during excavations of about ten nests in the first ten days of March 2026. This should indicate that the species is not very polygynous and at least not supercolonial. At the same time, masses of sexual brood, mainly last instar larvae and pupae, were found in many nests. It seems possible that the collecting team did not have access to the queens because they resided in chambers very deep in the soil. Tapinoma elongatum sp. nov. was the absolutely dominating Tapinoma species in the investigated sand dune habitats. In this context, it is interesting that the supercolonial T. ibericum, which dominates all urban and rural areas in south Iberia, could not penetrate the natural dune areas along the coast. This can be explained by two reasons. Firstly, there was no free place for T. ibericum – the dune niche was already saturated by T. elongatum sp. nov. Secondly, as dispersal flights of mated gynes in all supercolonial species have not been observed so far and are either missing or exceptional, the spread of T. ibericum into remote areas depends on some kind of anthropogenous transport – either with dumped soil material, potted plants or hitchhiking with cars or lorries. This is practically excluded for natural dune areas and should occur only exceptionally in other more traffic-prone areas. The only two T. ibericum nests found during the survey in March 2026 were situated at the margin of unfixed driveways in more humid cattle and horse pastures with stabilised sandy soils in the Doñana National Park. One site was located 2.5 km north and the other one 3.4 km west of the Doñana National Park field station – at the latter site T. ibericum occurred syntopically with T. elongatum sp. nov.