HADROTARSINAE

Agnarsson, Ingi, 2004, Morphological phylogeny of cobweb spiders and their relatives (Araneae, Araneoidea, Theridiidae), Zoological Journal of the Linnean Society 141 (4), pp. 447-626 : 466-467

HADROTARSINAE : CLADE 52

Hadrotarsine monophyly is strongly supported, although one of the putative synapomorphies, ALS stridulatory ridges, suggested by Forster et al. (1990) and Griswold et al. (1998: character 67) is doubtful. Hadrotarsus has stridulatory ridges on the ALS and Griswold et al. observed these in both Emertonella , and Dipoena . However, I have examined three Dipoena species , including their exemplar ( D. nigra Emerton ; Fig. 6D ) as well as D. torva Thorell , and D. cf. hortoni (pers. observ.), and none have stridulatory ridges. Gmogala also lacks such stridulatory ridges (pers. observ.). Either Dipoena has secondarily lost this supposed hadrotarsine synapomorphy, or the character is synapomorphic for a subsidiary hadrotarsine clade [so far known only from Hadrotarsus , Emertonella , and Euryopis (203, Fig. 9B )].

An identical stridulatory mechanism also occurs in Chilenodes ( Malkaridae : Palpimanoidea) ( Platnick & Forster, 1987). The placement of Chilenodes and many other palpimanoids is dubious at best ( Schütt, 2002). Classical palpimanoids are two-clawed with claw tufts, have plumose body setae, lack paracymbia and have a palpal conformation entirely different from araneoids. Chilenodes (Malkaridae) , however, along with (at least) the families Mimetidae , Holarchaeidae , Pararcheidae and Micropholcommidae (all currently Palpimanoidea, but see Schütt, 2000, 2002 for alternative placement) are three-clawed, have serrate body setae (otherwise a highly conserved araneoid synapomorphy), have a typical araneoid palpal conformation (e.g. with an embolic tegular membrane) and a paracymbium; an araneoid synapomorphy. Lehtinen (1996) came to similar conclusions based on leg cuticle ultrastructure. If the placement of Chilenodes in Araneoidea is confirmed, this character may indicate relatedness with hadrotarsines. Interestingly, another malkarid, Sternodes foraminatus Butler , shares some unique features with Phoroncidia (see Fig. 62A–D , and legend).

Nonetheless, several characters unite hadrotarsines including Dipoena , such as: the presence of two pairs of spermathecae (10, Fig. 93I ), sperm duct entering the embolus (left palp, ventral view) counter-clockwise (60), cheliceral promargin without teeth (106, Fig. 5F ), shortened paturon (117, Fig. 5C ), thin cheliceral bases (118, Fig. 5D ), long and slender cheliceral fangs (120, Fig. 9F ), high carapace (124, Fig. 5D ), carapace nearly as wide as long (126), triangular labium (136, Fig. 5A ), palmate female palpal claws (177, Fig. 9E ), grouped flat-tipped sensory setae on tarsus I (197, Fig. 8C, D ), FL absent (212, Fig. 8A ), a functional male AG (219, Fig. 6F , males, as females, lack FL). The loss of prey-catching webs (224) is an ambiguous synapomorphy, but there have been no observations of prey-catching on D. nigra .

Wunderlich’s (1978) synonymy of Hadrotarsidae with Theridiidae produced a monophyletic group, but resulted in a family name with much broader circumscription and less utility. The distinctness of hadrotarsines and the absence of some classical theridiid synapomorphies - male palpal tibial rim setae (16, Fig. 13C ), rim orientation (17, Fig. 10A ), abdominal stridulatory picks (150, Fig. 18B–D ), dorsal suprapedicellate proprioreceptors (163, Fig. 43A, B ), and theridiid type tarsal comb (194, Fig. 11E, F ; 195, Fig. 59A, B ) - speak of the revalidation of Hadrotarsidae (see also Baert, 1984a, b), contra Wunderlich (1978) and Griswold et al. (1998). However, the phylogenetic position of this clade is contradicted in current molecular research, where Hadrotarsinae is embedded within Theridiidae ( Arnedo et al., 2004) . If correct, elevating Hadrotarsinae to family level would render Theridiidae as here circumbscribed paraphyletic; such a decision therefore awaits a combined analysis.

Griswold et al. (1998) found hadrotarsines to nest within Theridiidae , but that result is not strongly supported by their data. A single character ( Griswold et al., 1998; character 65) unifies Anelosimus and the hadrotarsines in their cladogram; colulus reduced to less than half the length of its setae. However, as discussed in this study (172–175), Anelosimus lacks a colulus, in Dipoena the colulus is clearly larger than half the length of its setae, and the condition in Emertonella (colular area strongly invaginated) is unique. If only these entries in the matrix of Griswold et al. (1998) are changed accordingly, a sister relationship between Hadrotarsinae and the remaining theridiids becomes an equally good explanation of their data.

Hadrotarsinae includes the following 14 genera: Anatea , Audifia , Dipoena , Dipoenata , Emertonella , Euryopis , Eurypoena Wunderlich 1992 , Gmogala , Guaraniella , Hadrotarsus , Lasaeola , Trigonobothrys , Yaginumena and Yoroa .

Figures

Figure 5. Dipoena nigra. A, female labium; the triangular shape is a synapomorphy of Hadrotarsinae (136-1). B, tip of male chelicera; note plumate hairs (121-1). C, D, male prosoma. C, front view, the short cheliceral paturon (arrow) is a synapomorphy of Hadrotarsinae (117-1). D, side view of the elevated prosoma (124-1). E, female prosoma side view, less elevated than in male; note also the short and thick segments of the palp. F, female cheliceral fang, both promargin (106-1) and retromargin (110-1) without teeth. G, tip of male fourth tarsus. Scale bars: A, B, 50 Mm; C–E, 100 Mm; F, G, 10 Mm.

Figure 6. Dipoena nigra. A, serrated bristles of tarsal comb (193-1, 194-0, 195-0); compare to the characteristic theridiid tarsal comb, e.g. Achaearanea (Fig. 11E, F). B, C, tip of tarsus I female. B, note presence of grouped flat tipped setae ventrally (arrow), a Hadrotarsinae synapomorphy (197-1). C, ventral view. D, female spinnerets, FL is probably absent (212-1), the size and shape of the AGs is uncertain, but probably one is enlarged and flattened (215-1, see male in F); note also the absence of stridulatory ridges on ALS (arrow, 203-0), previously thought to be a hadrotarsine synapomorphy. E, Dipoena torva female PLS, with a small AG, lacking FL. F, male PLS has a functional (219-1), flattened AG, the second non-AC spigot is morphologically similar to FL, but given the condition in the female is probably an AG. Scale bars: A–C, 20 mm; D, 50 mm; E, F, 10 mm.

Figure 8. Euryopis gertschi. A, female PLS; note absence of FL (212-1). B, tip of male tarsus IV; note short central claw (upper arrow, 200-2) and serrated setae of the hadrotarsine tarsal comb (lower arrows, 193-1, 194-0, 195-0). C, tip of female tarsus I; note short central claw (upper arrow) and grouped flat tipped setae ventrally (lower arrow, 197-1). D, ventral view of flat tipped setae, probably sense chemicals (taste) by touch. E, long and slender hadrotarsine cheliceral fang (120-1); note unusual outgrowth at base (arrow). F, details of cuticular outgrowth at base of male fang; this is the only species in which I have seen this structure, and its function (if any) is unknown. Scale bars: A, D, 10 mm; B, E, 50 mm; C, F, 20 mm.

Figure 9. Euryopis and Emertonella. A–D, spinnerets. A, B, female Euryopis flavomaculata. A, all. B, ditto, left spinning field; note ridges on ALS (203-1) and the absence of FL on PLS (212-1). C, D, Emertonella funebris male. C, left field; note presence of functional AG (219-1). D, colular setae; note invagination of the colular area (vertical arrow, 172-2), and the pair of long colular setae (horizontal arrows). E, E. flavomaculata palpal claw; the palmate condition (177-1) is a synapomorphy of Hadrotarsinae. F, ditto, cheliceral fangs. Scale bars: A, B, E, F, 50 mm; C, D, 20 mm.

Figure 10. Achaearanea tepidariorum. A–C, male palp. A, ventral. B, retrolateral; note split in the embolus (94-1). C, dorsal, the BCH (23-1) is a putative synapomorphy of Achaearanea. D, E, dorsal portion of male prosoma, showing stridulatory ridges (128-1) near the pedicel (PE). F, male abdomen, showing SPR (150-1) and nubbins (SN, 149-1) around the pedicel, the additional stridulatory picks (ASP) are found in Achaearanea and some other theridiines (162-1). Scale bars: A–D, F, 100 mm; E, 10 mm.

Figure 11. Achaearanea tepidariorum. A, male SPR and nubbins. B, female PLS. C, D, female palpal claw, showing semi palmate condition (177-2). E, F, female fourth tarsus. E, theridiid tarsal comb (193-1). F, individual setae of the tarsal comb with longitudinal grooves (194-1), and hooked comb condition (195-1). Scale bars: A, E, F, 100 mm; B, C, 50 mm; D, 10 mm.

Figure 13. Ameridion, male. A–C, Ameridion nr. petrum, palp. A, mesial. B, ventral; note elongated tibia. C, ventral closeup. D, E, Ameridion sp. palp. D, mesial. E, expanded; note cymbial outgrowth containing Chd (22-1). F, Ameridion nr. petrum, prosoma and left palp; note basal cheliceral knobs (upper arrow, 115-1) and a relatively long palpal tibia (lower arrow). Scale bars, A–C, E, F, 100 mm; D, 50 mm.

Figure 18. Anelosimus eximius. A, tip of cymbium of the expanded palp; note depressed tip (arrow), the light sclerotization of the cymbial tip is a synapomorphy of Anelosimus (26-1). B, male SPR; curvy rows (159-1) are characteristic of some Anelosimus. C, the much less pronounced female picks. D, male SPR area; note also proprioreceptic setae (PR, left arrow points toward a dorsal (11 o’clock) proprioreceptor, 163-1). E, female spinnerets. F, female PLS and PMS. G, male PMS. Scale bars: A–D, 50 Mm; E–G, 20 Mm.

Figure 43. Crustulina sticta, female. A, abdomen, white box shows area enlarged in B. B, close-up of abdominal proprioreceptors (arrows); note setae of the modified SPR (see also in C) carry much shorter setae. C, anterior ventral abdomen, showing pedicel area, Ep and BL. D, tip of fourth tarsus. E, palpal tarsus; note small TO (arrow, 198-0), and serrated bristles ventrally. F, spinnerets. G, PLS. Scale bars: A–C, F, 100 Mm; D, E 50 Mm; G, 20 Mm.

Figure 59. Nesticodes rufipes, female. A, tarsal comb. B, serrated setae of tarsal comb. C–E, spinnerets. C, left field. D, ALS. E, PLS. F, epigynum. Scale bars: A, 100 Mm; B, 10 Mm; C, 50 Mm; D, E, F, 20 Mm.

Figure 62. Phoroncidia sp., male. A–D, palp. A, mesial; note spines on tegulum, such spines are also present in Sternodes foraminatus Butler (see Moran, 1986), originally in Palpimanidae, later made the type of Sternodidae (Moran, 1986) and then transferred to Malkaridae by Platnick & Forster (1987). Sternodes shares several additional features with Phoroncidia. B, ventral. C, dorsal. D, close-up of tegular spines (TS). E, prosoma, head shape is typical for males of this genus (103-2). F, stridulatory area of abdomen, highly reduced. G, posterior end of prosoma, no stridulatory ridges visible (150-0). H, epiandrous gland spigots. Scale bars: A–C, E–G, 100 Mm. D, H, 10 Mm.

Figure 93. A–D, models of male sperm duct trajectory. A, Anelosimus eximiu: ectal view, numbers indicate where the duct completes loops 1-3. B, A. eximius, dorsal view. C. Theridion. D, Faiditus. E-J, schematic illustrations. E, Faiditus chickeringi, ducts. F, Anelosimus rupununi, epigynum. G, Kochiura aulica, epigynum. H, A. rupununi, internal female genitalia. I, Dipoena nigra, internal female genitalia. J, Kochiura aulica, internal female genitalia. (F–H & J, drawn by Sarah Crews.)