Theodoxus syriacus (Bourguignat, 1852)

Sands, Arthur F, Gloeer, Peter, Guerlek, Mustafa E, Albrecht, Christian & Neubauer, Thomas A, 2020, A revision of the extant species of Theodoxus (Gastropoda, Neritidae) in Asia, with the description of three new species, Zoosystematics and Evolution 96 (1), pp. 25-66 : 25

Theodoxus syriacus (Bourguignat, 1852) Figure 21A-R

Neritina Syriaca Bourguignat 1852: 26; Martens 1874: 33, pl. 5, fig. 41; Martens 1879: 238, pl. 23, figs 9, 10; Kobelt 1899: 12-13, pl. 214, fig. 1348.

Theodoxus (Theodoxus) syriacus : Schütt and Seşen 1989b: 40-41.

Theodoxus syriacus : Yıldırım 1999: 885; Gürlek et al. 2019: 2993; Glöer 2019: 53, fig. 42.

Type locality.

Beirut, Lebanon.

Type material.

The syntype series is supposed to be stored in MHNG but could not be found (E. Tardy pers. comm. 11/2018). The only material collected by Bourguignat available there was collected from İskenderun, Turkey (coll. no. MHNG-MOLL-111712) .

Remarks.

Bourguignat (1852) described T. syriacus from Beirut, Lebanon, which lacked a pseudo-apophysis. Martens (1874) lacked Bourguignat’s material, but he connected the name and diagnostic features to specimens from Kahramanmaraş, Turkey. Nothing conforming to T. syriacus has been found around Beirut in recent times ( van Damme 2014). However, Schütt and Şeşen (1989b), Yıldırım et al. (2006), and Gürlek et al. (2019) reported this species from a number of localities in south-east Anatolia. Sands et al. (2019a) sequenced specimens of Theodoxus from these localities and noted that the material that conformed to T. syriacus formed a distinct clade (also see Fig. 2 ). Interestingly, they also found that a specimen from Greece attributed to T. peloponensis ( Récluz, 1841) by Bunje and Lindberg (2007) was genetically linked to this species ( Sands et al. 2019a). Given the earlier description of T. peloponensis , that name would take precedence. However, the morphological conformity of this specimen to the type material of T. peloponensis could not be confirmed. Given the disjunct geographic distribution range this may be a case of a misplaced or mislabelled sample, and we encourage future review of this species.

Besides the lack of a pseudo-apophysis, T. syriacus operculum has a reduced rib-shield and an ivory calcareous base (Fig. 21D, H, L ). The shells are often uniform black or dark brown and less globular (elongated width), but occasionally speckled forms with ivory patches can be found (Fig. 21A-R ). Theodoxus syriacus shares close relationships with both T. wesselinghi sp. nov. and T. wilkei sp. nov. ( Sands et al. 2019a; Fig. 2 ). These species likely diverged from a common ancestor around the Pliocene-Pleistocene transition ( Sands et al. 2019a; Fig. 2 ).

Distribution.

South-eastern Anatolia and north-western Mesopotamia, particularly in Adana, Diyarbakır, Elazığ, Kahraman Maraş, Malatya, Mardin, and Tunceli provinces of Turkey ( Schütt and Şeşen 1989b; Yıldırım 1999; Yıldırım et al. 2006; Gürlek et al. 2019; Sands et al. 2019a; Fig. 3D ). Possibly regionally extinct or very localised in Lebanon and Syria ( van Damme 2014). Records from Greece are questionable and need confirmation.

Figures

Figure 2. Dated phylogeny of the genus Theodoxus constructed with BEAST, based on existing GenBank and newly incorporated data for COI, 16 S and ATPα (Suppl. material 1: Table S 1). Morphospecies where associations are queried are highlighted by a question mark after the species name (see the " Systematic checklist " for more information). Small green (PP ≥ 0.95) and red (PP <0.95) dots on nodes indicate the relative posterior probability support of divergence events. Node labels (1 - 32) correspond to divergence dates and HPD intervals in millions of years ago (Mya) for selected nodes (see Suppl. material 1: Table S 3). Dashed dark blue and light blue lines represent the minimum interspecific and maximum intraspecific variation determined by Sands et al. (2019 a) to aid Theodoxus spp. delimitation (see see Methods, Phylogenetics and species delimitation and that study for more information on the delimitation methods).

Figure 3. Occurrence map for Theodoxus spp. in Asia. All points conform to specimens used in the phylogenetic analyses (Suppl. material 1: Table S 1), except for T. gloeri for which no molecular data are available and only the type and paratype localities are indicated. Species are partitioned across four identical maps (A - D) to limit overlap of points as far as possible. Barring T. gloeri, closer related species are grouped together (Fig. 2).

Figure 21. Theodoxus syriacus (Bourguignat, 1852). A - D. Specimen collected at Sultankoeyue, Mardin, Turkey (UGSB 24182); E - H. Specimen from the Yanarsu Stream, Alicli, Turkey (UGSB 20518). I - L. Specimen collected near Basdegirmen, Diyarbakir, Turkey (UGSB 24183); M - O; P - R. Two specimens collected by Bourguignat from Iskenderun, Turkey (MHNG-MOLL- 111712). All UGSB specimens incorporated into the phylogeny (Fig. 2). Scale bars: 1 mm.