KONOL. SV. VET. AKADEMIENS HANDLINGAR. BAND. 13. N:0 5. 



65 



\' Gen. LATHRODECTUS Walck. ') 



L. 13-guttatus (Rd|isi), Var. lugubris (Duf.) niger vel iiigro-pieeus, jiedibus aut ni- 

 gris, aut piceis, fernoriHus, ))utellis et tibiis apice nigris; abdomine nigro, breviter piloso, 

 aut supra unicolore, aut in medio et lateribus antice lineis paucis brevibus transversis 

 curvatis vel sub-rectis pallidis notato, macula fiavescenti interduin supra anum; ventre 

 nigro plerumque fasciis ^uabus transversis flaventibus notato ; ordinibus oculorum versus 

 extreinitates paullo divaiicantibus; pedibus l:mi paris cephalothorace saltem 5:plo lon- 

 gioribus, tibiis ejusdein p^ris patella plus duplo, cephalothorace vero paullo longioribus; 

 vulvaj niargine postico in medio inciso. — 9 ad. Long. 11 — 12 (nonniimqiiam 8^-2 

 tantum) millim. 



Syn.: 1820. Theridion liig^bre Duf., Descr. de six Arachn. nouv., in Ann. gén. ti. Sc. phvs., IV, p. 355, 



Tab. LXIX, fig. 1. 



1825 — 7. Latrodectus erebiis Sav. et Aud., Descr. de FÉgypte, 2:e Éd., XXTI, p. 352, Atlas, 



Araclin., Pl. III, fig. 9. 



? 1837. Latrodectus 5-guttatus Kryn., Aiachuogr. Ross. dec. prima, in Bull. de la Soc. Imp. d. Nat. 



de Moscou, 1837, p. 75, Tab. VI, fig. 2. 

 1836. » hispidus [Meta hispida] C. Koch, Die Arachn., III, p. 9, Tab. LXXV, fig. 166. 



1845 — 7. n argus Luc, Explor. de TAlgérie, Anim. Art. I, p. 235 {ad part.: "variétés"). 

 1849. » lugubris Motsch., Not. s. deux Araignées venim., cet., in Bull. de la Soc. Imp. 



d. Nat. de Moscou, 1849, p. 290, Tab. II, figg. 3, 4. 

 1873. » erebus Sim., Aran. nouv. ou peu connus, cet., 2:e Mém., p. 92. 



Femina. — Cephalothorax 3^^ — 4^;, millim. longus, paullulo longior quara latior, inverse cordiformis 

 fere, in lateribus amplissime et fortiter rotundatus, postice truncatus, antice sinu parvo fortiter augustatus, parte 

 cephalica anteriora versus angustata, fronte ','3 latitudinis partis cephalicse aequanti; supra parum convexus, im- 

 pressionibus cephalicis profuudis, in fovea centrali ordinaria maxima et profunda, transversa et sub-stellata, pa- 

 rum pone pedes secundi paris sita coéuntibus; opacus, sat dense punctis minoribus impresso-punctatus, pilis 

 brevioribus sub-erectis prresertim in parte cephalica sat dense vestitus, nigro-piceus totus. Clypeus mox sub 

 oculis transverse impressus, convexus, intequalis, impresso-punctatus, altitudine duplam longitudinem areae oculo- 

 rum mediorum fere iequaus. Sternum piceum, nigro-pilosum, pilis in punctis parvis impressis positis. Labium 

 transversum, fere semi-circulatum, piceum, transverse striato-rugosum. OcuU sub-aequales; antici tamen posticis 

 paullulo majores videntur; series duaj versus extreraitates paullulo tantum divaricautes, oculis lateralibus paullo 

 longius inter se quam mediis anticis a mediis posticis distantibus; series postica paullo recurva, antica paullo 

 procurva; area raediorum parum longior quam latior postice, evidenter latior postice quara antice; medii antici 

 tuberculo communi impositi, intervallo oculi diametrura paullo superanti disjuncti, a latei'alibus evidenter, vix 

 tameu dimidio, longius remoti; spatium, quo distant oculi medii postici inter se, oculi diaraetro evidenter majus: 

 a lateralibus posticis spatio liac diametro duplo majore distant; intervallum inter oculos laterales oculi diametro 

 plus dimidio majus est. Mandibuhe in dorso fere rectpe, versus apicem sensim leviter angustat?e, tibiis anticis 



^) The abdomen of at least some Lathrodectus-species, f. inst. L. 13-guttatus and L. Curacaviensis (Mull.), 

 shows verv evident traces of segmentation. The whole apex of the abdomen is encircled by a furrow; the 

 segment thus formed includes the anus, mamillae and the yellow spöts at the sides of these latter organs. 

 On the under side of the abdomen this furrow is sometimes less distinct, except in the middle, where it 

 always forms a short transverse groove (with two openings?) towards the hinder part of the posterior 

 yellow ventral band. Another short transverse groove (slit?) is seeu in the middle between this groove 

 and the rima genitalis; there is also a transverse groove or slit immediately before the mamillje. — In 

 the embryo of spiders, the abdonien, as is known, is evidently segmentated, with 5 (as in Pholcus) or 

 more segments. (Conf. f. inst. Claparéde, Recherches sur Févolution des Araignées, in Natuurkund. Ver- 

 handeliugeu uitgegev. d. het Provinciaal Utrechtsche Genootschap v. Kunsten en "VVetenschappen I, 1 (1862)). 

 By the above uamed grooves and the rima genitalis, the limits of 5 original segments are probably indi- 

 cated. (There appear also to exist two small openings just behind the rima genitalis, which perhaps 

 mark the limit of a 6:th segment). The furrows and grooves here mentioned may also be observed in other 

 spiders, f. inst. in several species of the genera Lithypliantes and Steatoda. 



K. Vet. Ak.Kl. Hnn.U. Bd. \Z. X:o 5. 9 



