Cenemus Saaristo, 2001 (Family Pholcidae C.L. Koch, 1850)

Huber, Bernhard A. & Meng, Guanliang, 2023, On the mysterious Seychellois endemic spider genus Cenemus (Araneae, Pholcidae), Arthropod Systematics & amp; Phylogeny 81, pp. 179-200 : 179

3.2.1. Genus Cenemus Saaristo, 2001 (Family Pholcidae C.L. Koch, 1850)

Cenemus Saaristo, 2001: 19 (type species: Holocnemus culiculus Simon, 1898).

Description.

The three species currently included in this genus are extremely similar to each other. The redescription of the type species below thus covers the genus except for some minor details of the genitalia (cf. Saaristo 2001, 2002).

Diagnosis.

Large, long-legged pholcids with deep carapace pit and cylindrical abdomen; distinguished from similar Smeringopinae (especially Smeringopus ; also Holocnemus and Smeringopina Kraus, 1957) by the combination of: (1) male gonopore with six epiandrous spigots (Fig. 31 ; only two in Smeringopus and Smeringopina ); (2) ALS with only two spigots each (Fig. 63 ; seven to eight in Smeringopus and Smeringopina ); (3) male chelicerae with one pair of apophyses, each with one conical hair at tip (Fig. 33 ; two or more hairs in certain Holocnemus and other Smeringopinae ; some Smeringopinae without conical hairs); (4) male and female chelicerae with distinct stridulatory files (Figs 36 , 49 ; absent in Smeringopus and Smeringopina ); (5) palpal tarsus without macrotrichia (Figs 9-11 ; often present in Smeringopus and Smeringopina ); (6) procursus tip without ventral spine (Fig. 20 ; present in most other Smeringopinae ); (7) male anterior femora without spines (present in Holocnemus , Crossopriza , Stygopholcus , and Hoplopholcus ); (8) prolateral trichobothrium of tibia 1 absent (present in Smeringopus and Smeringopina ); (9) tarsal pseudosegments distinct (Fig. 56 ; indistinct in all other Smeringopinae ); (10) leg tarsal organs oval, with indentation in proximal median part of rim (Figs 58-61 ; round and without indentation in all other Smeringopinae ).

Natural history.

Nothing has been published about the biology of Cenemus before. Given the high general similarity of the three known species, the basic observations on C. culiculus below are probably valid for all of them.

Relationships.

Cenemus is part of the northern group of Smeringopinae . Its sister group remains unclear (see Discussion).

Composition and distribution.

Three species endemic to the Seychelles (Fig. 2 ): Cenemus culiculus (Simon, 1898) ( Mahé and Silhouette); C. silhouette Saaristo, 2001 (Silhouette); and C. mikehilli Saaristo, 2002 (La Digue and Marianne). All available evidence suggests that Cenemus is indeed restricted to the Granitic Seychelles. Given the size of the spider and the easily visible large webs, it seems very unlikely that Cenemus has been overlooked in other regions.

Figures

Figure 2. Known distributions of the northern and southern groups of Smeringopinae and of Cenemus. Excluded from this map are three widely distributed synanthropic species: Holocnemus pluchei (Scopoli, 1763); Crossopriza lyoni (Blackwall, 1867); and Smeringopus pallidus (Blackwall, 1858). Also excluded are Australian records of Smeringopus natalensis Lawrence, 1947. Note that the southern group ranges into the southern Arabian Peninsula but the respective blue dots are covered by orange dots.

Figures 29 - 37. Cenemus culiculus (Simon, 1898); male from Mahe, Morne Blanc (ZFMK Ar 23868). 29 Ocular area and carapace, dorsal-frontal view. 30 Left eye triad and AME, oblique frontal view (arrows: " accessory lenses "). 31 Gonopore. 32 Spinnerets. 33 - 34 Modified hair on cheliceral apophysis. 35 Pores on frontal cheliceral face. 36 Cheliceral stridulatory file. 37 Palpal coxa (endite), prolateral view. Scale bars: 100 µm (29, 30, 36); 10 µm (31 - 35); 20 µm (37).

Figures 55 - 63. Cenemus culiculus (Simon, 1898); female from Mahe, Morne Blanc (ZFMK Ar 23869). 55 Palpal tarsal organ. 56 Left tarsus 3, showing distinct pseudosegmentation. 57 Tip of left tarsus 2 (arrow: tarsal organ). 58 - 59 Tarsal organ on tarsus 1. 60 - 61 Tarsal organs on tarsi 3 and 4. 62 - 63 Spinnerets. Scale bars: 10 µm (55, 58 - 63); 100 µm (56); 20 µm (57).

Figures 47 - 54. Cenemus culiculus (Simon, 1898); female from Mahe, Morne Blanc (ZFMK Ar 23869). 47 Carapace pit. 48 AME and clypeus, oblique frontal view (arrow: modified area). 49 Cheliceral stridulatory file. 50 Pores on frontal cheliceral face. 51 Epigynum and anterior sclerite, lateral-ventral view. 52 Epigynum, ventral view (arrows: pockets). 53 Epigynal pit. 54 Internal female genitalia, dorsal view with dorsal arc tilted toward front (asterisk: pore plate). Abbreviations: da, dorsal arc; va, ventral arc. Scale bars: 100 µm (47, 48, 51, 52, 54); 20 µm (49); 10 µm (50, 53).

Figures 5 - 11. Cenemus culiculus (Simon, 1898), live specimens and male pedipalp. 5 - 6 Male and female from Mahe, Bel Ombre. 7 - 8 Female with egg-sac and juvenile male from Mahe, Morne Blanc. 9 - 11 Left male palp, prolateral, dorsal, and retrolateral views; male from Mahe, Morne Blanc (ZFMK Ar 23868). Abbreviations: co, coxa; fe, femur; gb, genital bulb; pa, patella; pr, procursus; ta, tarsus; ti, tibia; tr, trochanter. Scale bar: 0.5 mm.

Figures 18 - 20. Cenemus culiculus (Simon, 1898); male from Mahe, Morne Blanc (ZFMK Ar 23868); left tarsus and procursus, prolateral, dorsal, and retrolateral views; arrows point at distal dorsal sclerite. Scale bar: 0.5 mm.