Nemesia apenninica

Decae, Arthur, Pantini, Paolo & Isaia, Marco, 2015, A new species-complex within the trapdoor spider genus Nemesia Audouin 1826 distributed in northern and central Italy, with descriptions of three new species (Araneae, Mygalomorphae, Nemesiidae), Zootaxa 4059 (3), pp. 525-540 : 527

The apenninica group (new species-complex within the genus Nemesia )

The apenninica group is a newly recognized and defined phenetic group of medium-sized (Decae 2005), broadly similar looking species. Morphologically, members of the apenninica group differ from those of other Nemesia species groups by the absence of longitudinal ribs on the proximal embolus of the male bulb in combination with centrally twisted receptacles in female spermathecae.

The distribution of the apenninica group ( Fig. 8 ) is limited in the north and north-west by the Alpine mountain ranges. In the east by the Adriatic Sea and the Po Delta. In southern Italy the apenninica group is replaced by another phenetically defined Nemesia species-complex that might informally be referred to as the maculatipes group (based on N. macultipes Ausserer, 1871 ) on grounds of the conspicuous dark pigmented blotches (maculae) found on legs and/or PLS of its member species ( Decae & Di Franco 2005, Isaia & Decae 2012). Males of the two groups differ in the morphology of the embolus, with fine ribs (proximal) and a flexible filamentous tip (distal) in the maculatipes group versus a smooth embolus (proximal) and stiff sclerotized tip (distal) in the apenninica group. Females of the two groups differ in the presence or absence of maculae. In central Italy the apenninica group and the maculatipes group widely overlap. In Liguria (coastal north-western Italy) the distribution of the apenninica group appears to be limited to the eastern part of the region (Levante). In western Liguria (Ponente) the apenninica group appears to be replaced by N. manderstjernae (L. Koch, 1871) and N. carminans (Latreille, 1818) , belonging to two very different Franco-Iberian species-complexes.

Three species (all described below) are currently recognized within the apenninica group. Fig. 2 shows a living female, illustrating the general appearance of all species included in the apenninica group. Fig. 3 shows male and female specimens preserved in 70% ethanol. Although broadly similar in general appearance ( Fig. 4 ) the three species show distinctive differences in the morphology of the male bulb ( Figs 5 A, D–7A, D) but less distinctive differences in the structures of the spermathecae ( Fig. 5 E–7E).

Preliminary observations (Decae et al., in prep.) indicate that the apenninica group might be more diverse than presently perceived, with currently undescribed species occurring in Toscana and Corsica. Extensive samples of Nemesia from southern Italy and Sardinia however suggest the absence of the apenninica group in those regions. Current information indicates that the apenninica group comprises all Nemesia species found in the northern Apennine regions (including parts of eastern Liguria, southern Lombardia, Emilia-Romagna, Toscana and southern Piemonte). Therefore, the apenninica group is here regarded to be a distinct biological and biogeographical unit in the wider Mediterranean Nemesia fauna.

Figures

FIGURE 2. Dorsal view of living adult female N. hastensis n. sp. (BL » 18 mm) showing general appearance of Nemesia species included in apenninica group. Note: difference in color intensity between living and preserved specimen (Fig. 3).

FIGURE 3. General appearance of 70 % ethanol preserved N. hastensis n. sp. of apenninica group. Left, male BL = 13.6 mm; right, female BL = 17.7 mm.

FIGURE 4. Broadly similar appearance of three Nemesia new species, described below, of the apenninica group: A, N. apenninica (f), CL = 5.4 mm; B, N. apenninica (m), CL = 5.3 mm; C, N. hastensis (f) CL = 5.3 mm; C, N. hastensis (m), CL = 4.7 mm; D, N. pedemontana (f), CL = 5.8 mm; E, N. pedemontana (m), CL = 4.3 mm. Variations in pigment patterns (although generally slightly darker in N. pedemontana), carapace shape seen here have only weak diagnostic value in Nemesia species level taxonomy.

FIGURE 5. Nemesia apenninica n. sp.: camera lucida drawings of right male palpal organ (A – D) and in dorsal view, female spermathecae (E). Asymmetrically shaped palpal organ shown under four rotation angles around longitudinal axis (ax). A = ventral, B = dorsal, C = retrolateral, D = prolateral, the spermathecae are drawn in ventral view.

FIGURE 8. Collection sites of Nemesia species included in apenninica group. N. apenninica n. sp. (red dots), Nemesia hastensis n. sp. (blue dots), and N. pedemontana n. sp. (yellow dots). Note distributional segregation between N. hastensis and N. apenninica and the relatively wide and overlapping distribution of N. pedemontana. Apparent gaps in distribution ranges of N. apenninica and N. pedemontana are result of incomplete sampling.