Fossil and extant species of the genus Leptopholcus in the Dominican Republic, with the first cases of egg‐parasitism in pholcid spiders (Araneae: Pholcidae)

Representatives of the pholcid spider genus Leptopholcus are extremely rare on the American mainland, but fairly common on the major Caribbean islands. Previously, four extant Caribbean species were known, each one endemic to one of the Greater Antilles. Here we describe the first fossil representative of the genus, Leptopholcus kiskeya Huber and Wunderlich n. sp., originating from Dominican amber about 20 million years old. Two new extant species from the Dominican Republic are also described, L. toma Huber n. sp. and L. baoruco Huber n. sp., and new records are given for the widely distributed L. hispaniola Huber, 2000. Egg‐parasitism by a wasp of the genus Baeus Haliday (Scelionidae, Baeini) is documented for L. baoruco and L. hispaniola. These are the first records of egg‐parasitism in Pholcidae, and the first Neotropical Baeus species to parasitize spiders other than Araneidae and Theridiidae.


Introduction
The genus Leptopholcus has an interesting geographic distribution: it is widely distributed in the Old World tropics, but in the New World it is largely restricted to the Greater Antilles. Only recently, Leptopholcus was also recorded from the New World mainland (Huber et al. 2005), but in contrast to the Greater Antilles, where Leptopholcus is widely distributed in humid forests and has been frequently collected on each island, the three South American species are rare relicts in low precipitation areas. Since the usual habitat of Leptopholcus (underside of large live leaves) is in South and Central America occupied by representatives of the pholcid genus Metagonia, it has been suggested that this peculiar biogeography is the result of competitive exclusion (Huber et al. 2005). In agreement with this idea, Metagonia is largely absent from the Greater Antilles, where it is represented by a single troglomorphic species known from a Cuban cave (Pérez González and Huber 1999).
The distribution of Leptopholcus thus suggests that New World representatives are old relicts, derived from spiders present in the area before the break up of Pangaea in the Mesozoic. It was thus reasonable to expect that Leptopholcus was present on Hispaniola at the time of origin of Dominican amber, about 20-40 million years ago (Poinar 1992). This expectation was also based on the fact that pholcids are well represented in Dominican amber (Wunderlich 1988). Actually, more fossil than extant pholcid species are currently known from Hispaniola (Penney and Pérez-Gelabert 2002). Recently, one of us (J.W.) discovered an adult male specimen of Leptopholcus in Dominican amber. In the present paper we describe this new species and compare it with the previously described L. hispaniola as well as with two newly described species. This is the first in a series of papers on newly collected material that will elevate the number of known extant Hispaniolan pholcids from eight to about 25 species.
Egg-parasitism by wasps and flies is a common phenomenon in spiders (e.g. Disney 1994;Foelix 1996), but no case has previously been known for pholcid spiders, who carry their egg sacs with their chelicerae until the spiderlings hatch. Here we describe the first such case, involving scelionid wasps of the genus Baeus and at least two Dominican Leptopholcus species.

Materials and methods
The amber piece containing the fossil species described herein will be deposited in the Senckenberg Museum Frankfurt (SMF). The mine where is was found is unknown. All other specimens treated were collected by the first author during an expedition to the Dominican Republic in November and December 2005. The material is currently at the Alexander Koenig Zoological Research Museum, Bonn (ZFMK), but will later be partly transferred to the Museo Nacional de Historia Natural, Santo Domingo. Style of descriptions is as in Huber (2000). Measurements are in mm unless indicated otherwise. Drawings were done with a camera lucida, either on a Leitz Dialux 20 compound microscope or a Wild dissecting microscope. Photographs were made with a Nikon Coolpix 995 digital camera (204861536 pixels) mounted on a Nikon SMZ-U dissecting microscope. For SEM photographs, specimens were cleaned ultrasonically, dried in hexamethyldisilazane (HMDS) (Brown 1993), and photographed with a Hitachi S-2460 scanning electron microscope.

Etymology
The species name is a noun in apposition, derived from the type locality.

Diagnosis
Distinguished from known Caribbean congeners by the shapes of the apophyses on the male genital bulb, especially the unique appendix (Figures 3a, 4b, c, 9a), by the shape of the procursus (Figure 3b Figure 2a). Ocular area slightly elevated, with lateral triads on distinct low humps; distance PME-PME 285 mm; diameter PME 100 mm; distance PME-ALE 20 mm; distance AME-AME 85 mm, diameter AME 20 mm. Thoracic furrow absent. Sternum about as wide as long (0.6). Chelicerae with proximo-lateral projections and two modified hairs on distal apophyses (Figures 3c, 4d). Palps as in Figure 3a, b; coxa unmodified, trochanter with short retrolateral and long ventral apophyses, the latter with distal modified hair ( Figure 4h); femur with two small apophyses retrolaterally and one larger projection ventrally; procursus strongly bent dorsally, distal part longer than in other species, with distinctive distal structures ( Figure 4e); genital bulb with distinctive uncus and appendix and slightly sclerotized embolus (Figures 3a, 4b, c, 9a); palpal tarsal organ capsulate ( Figure 4f). Retrolateral trichobothrium of tibia 1 at 6%; prolateral trichobothrium absent on tibia 1, present on other tibiae; legs without spines and curved hairs, few vertical hairs; serrated hairs on tarsi 4 as in L. toma (cf. Figure 8g); pseudosegments on tarsi very indistinct, only a few visible distally. Gonopore with four epiandrous spigots ( Figure 4g). Spinnerets as in female (see below).

Variation
The pattern on the abdomen is fairly constant but variably distinct. Tibia 1 in two other males: 8.4, 8.7.

Female
In general similar to male, but abdomen tip mostly longer, in some cases much longer (Figure 2g, h), and ocular area not darker. Pattern on abdomen usually less distinct, in some cases even missing. All specimens with small but distinct AME lenses ( Figure 4a). Usually with pair of small grey marks behind ocular area. ALS with one widened, one pointed, and five cylindrically shaped spigots (Figure 4i), PMS with two small pointed spigots, PLS without spigots. Epigynum with median rounded projection (Figures 3d, 4j), with distinctive internal sclerotized structures, very elongated pore plates (Figures 3e, 4k). Tibia 1 in 18 females: 5.8-6.8 (mean: 6.4). Serrated hairs on tarsi 4 as in male.

Distribution
Known only from type locality ( Figure 10).

Diagnosis
Distinguished from known Caribbean congeners by the shapes of the apophyses on the male genital bulb (Figures 5a, 6a-c, 9b), by the shape of the procursus (Figure 5b), by the short male palpal trochanter apophysis (Figure 5b), and by the internal sclerotized structures in the female genitalia (Figures 2j, 5c, d). From L. toma and L. baoruco also distinguished by the shorter abdomen tip (Figure 2d).

Variation
All males (and females) from the Cordillera Central (La Cienaga; near Jima) have distinct AME spots (sometimes apparently even lenses), while males (and females) from all other localities lack these spots as well as any trace of AME lenses. The genitalia (male and female) in all these specimens are indistinguishable. Tibia 1 in 36 males: 6.3-8.3 (mean: 7.2).

Female
The single female specimen available at the time of the original description was from Haiti, Damiens (Huber 2000). The newly collected material clearly shows that this female specimen is not conspecific with the type specimen of L. hispaniola, but probably represents an undescribed species. Females of L. hispaniola have relatively short abdominal tips (similar to males), and the distinctive internal sclerotized structures in the genitalia differ markedly from those of the Haitian specimen (compare Figure 5d with Figure 308 in Huber 2000). Tibia 1 in 56 females: 4.7-6.6 (mean: 5.4). Epigynum as in Figures 5c, 6j; internal genitalia with oval pore plates (Figures 5d, 6m). Palpal tarsus with short distal cone-shaped claw, pair of strong hairs, and capsulate tarsal organ (Figure 6l). Figure 6k shows a female from La Cienaga with distinct AME pigment but without any trace of AME lenses. Serrated hairs on tarsi 4 as in male.

Distribution
Known from several localities in central, northern, and eastern Dominican Republic

Etymology
The species name is a noun in apposition, derived from the type locality.

Diagnosis
Distinguished from known Caribbean congeners by the shapes of the apophyses on the male genital bulb (Figures 7a, 8b, c, 9c), by the shape of the procursus (Figures 7b, 8a), and by the internal sclerotized structures in the female genitalia (Figures 2k, 7c, d). From L. hispaniola also by the much longer male palpal trochanter apophysis ( Figure 7b) and longer abdominal projection beyond the spinnerets ( Figure 2f); from L. baoruco also by the light ocular area (Figure 2e).

Variation
The other male from the type locality is slightly paler, with less distinct spots on the abdomen. The male from near Cabral has very similar palps, including the shape of the procursus, but the bulbal apophyses (especially the uncus) differ quite clearly (Figure 9d). This male is therefore assigned tentatively. Tibia 1 in other male from type locality: 6.1; male from near Cabral: 6.5.

Female
In general similar to male, but abdomen tip longer. AME pigment always present, but lenses indistinct (Figure 8f), in the dissecting microscope sometimes not visible. Epigynum with median rounded projection (Figures 7c, 8k), with distinctive internal sclerotized structures and roundish pore plates (Figures 7d, 8l, m). Palpal tarsus with short distal coneshaped claw, pair of strong hairs, and capsulate tarsal organ (Figure 8h). Tibia 1 in three females from type locality: 4.6-4.7; female from near Cabral: 4.6; females from Santo Domingo: 3.9, 4.3. Tarsus 4 with single row of serrated hairs ventrally (Figure 8g). Spinnerets as in Figure 8i, ALS with one widened, one pointed, and five cylindrically shaped spigots (Figure 8j), PMS with two small pointed spigots, PLS without spigots.

Distribution
Known from three localities in southern Dominican Republic ( Figure 10). Note that the specimens from two of these localities are assigned tentatively (see below).

Etymology
Kiskeya (or Quisqueya) was the name of Hispaniola used by the Taínos, an Arawakspeaking people originally occupying the island. It is here used as a noun in apposition.

Diagnosis
Distinguished from extant Caribbean Leptopholcus species by the long and slender procursus that is widened distally on the ventral side (Figure 11c; not widened on the dorsal side like L. hispaniola and L. toma), and by the shapes of uncus and appendix; from L. hispaniola also by the longer trochanter apophysis and the presence of distinct AME Figure 11. Leptopholcus kiskeya, holotype. (a) Entire specimen in ventral view; (b) body without legs, dorsal view; (c) prosoma with chelicerae and palps (grey), frontal to ventral view. l1, 3, left legs 1 and 3; ps, proximal bulbal sclerite; r1-4, right legs 1-4; tr, trochanter.
lenses; from L. baoruco and L. toma apparently also by the abdomen tip that barely projects beyond the spinnerets.

Unknown
Distribution Dominican Republic; mine not identified.

Material examined
Only type above.

Other inclusions
The amber piece contains four additional specimens: one 'acalyptrate' fly and one ceratopogonid (Diptera, kindly identified by B. Sinclair), one Hymenoptera, and one unidentified neopterous insect.

Egg-parasitism
In L. baoruco, at least four of the nine egg sacs collected in the field were parasitized by a wasp of the genus Baeus Haliday (Baeini, Scelionidae). In two of them, all eggs had a developing wasp inside, which is easily visible through the egg shell (Figure 1f). In the other two egg sacs (one of them is the median one in Figure 1f), two and one eggs, respectively, remained unparasitized (Table I). In L. hispaniola, one of six egg sacs was parasitized (originating from La Cienaga). In most egg sacs, there was a strong bias towards females