Metagonia, SIMON, 1893

HUBER, BERNHARD A., 2000, New World Pholcid Spiders (Araneae: Pholcidae): A Revision At Generic Level, Bulletin of the American Museum of Natural History 2000 (254), pp. 1-348: 53-55

publication ID

http://doi.org/ 10.1206/0003-0090(2000)254<0001:NWPSAP>2.0.CO;2

persistent identifier

http://treatment.plazi.org/id/03ACD276-8F60-FFDF-FF77-FCD644443EDA

treatment provided by

Felipe

scientific name

Metagonia
status

 

METAGONIA SIMON, 1893  

Metagonia Simon, 1893b: 472   (type species by original designation M. bifida Simon, 1893   ; examined). – Gertsch, 1971: 82–83; 1977: 105; 1986: 40–41. – Gertsch and Peck, 1992: 1194– 1195. – Huber, 1997a: 342.

Anomalaia González-Sponga, 1998: 24   (type species by original designation A. mariguitarensis González-Sponga, 1998   ; examined). NEW SYN- ONYMY.

JUSTIFICATION OF SYNONYMY: The type species of Anomalaia   shares with ‘‘typical’’ Metagonia species   (i.e., southeast Brazilian species herein considered closely related to the type species, which is only known from the female) the asymmetrical female internal genitalia, the hinged process on the procursus, and the dorsal attachment of the bulb to the cymbium.

DIAGNOSIS: Small to medium-sized (total length usually ~ 1.5–3 mm), usually pale, long-legged leaf- and cave-dwellers, AME always missing. Easily distinguished from other New World genera by the simple, often dorsally attached bulb consisting of a globular part and a tubular embolus ending in a spine, by the male clypeus that is usually sexually modified, by the complex procursus that is usually provided with a ventral hinged process, and by the vulva that is usually pro- vided with a complex system of sclerotized ducts. Distinguished from the putative sister group (Old World Pholcus   group sensu Hub- er, 1995) by the ventral hinged process of the procursus, and by the absence of any bulbal projection other than the embolus.

DESCRIPTION: Total length usually ~ 1.5–3 mm, rarely up to 5 mm (e.g., M. caudata O. Pickard-Cambridge   ). Carapace roundish, ocular area barely elevated (figs. 1–2); ochreyellow, sometimes with distinct brown pattern (figs. 201, 210, 282); thoracic groove usually absent (present in M. globulosa   , n. sp.; fig. 280). Six eyes in two triads, absent in some troglobites, AME always missing. Distance PME-ALE small (~ 15–25% of PME diameter). Male clypeus usually with sexual modifications, usually species-specific. Male chelicerae usually with modified hairs (figs. 28–29), sometimes with one or more pairs of frontal apophyses, rarely with lateral stridulatory ridges (figs. 40, 273, 285). Male palps large in relation to overall size; coxa without retrolateral apophysis, femur sometimes with conspicuous ventral or prolateroventral apophysis (e.g., fig. 246), procursus usually complex, with ventral hinged process (figs. 208, 213, 258, 276); bulb often attached dorsally to cymbium, with tubular embolus ending in spine (fig. 53), without further projections. Tarsal organ capsulate in all species examined ( M. argentinensis Mello-Leitão   , rica Gertsch   , blanda Gertsch   , tinaja Gertsch   , delicata (O. Pickard-Cambridge)   , uvita Huber   , globulosa   , n. sp., maldonado   , n. sp.; figs. 61–66). Legs usually thin and long (leg 1 usually ~ 8–13 X body length; in M. globulosa   only 4.4 X body length; tibia 1 l/d: 50–100; in M. globulosa   only 26), leg 1 always longest, legs 2 and 4 about same length, leg 3 shortest; often with darker patellae and tibia-metatarsus joints, sometimes with up to three dark rings on femora and tibiae; without spines, vertical and curved hairs; retrolateral trichobothrium of tibia 1 at ~ 7–15%, more distally only in M. globulosa   (21–23%); tarsus 1 with ~ 20– 30 pseudosegments that are distinct distally, but difficult to count proximally. Opisthosoma very variable in shape, from globular to cylindrical to bifid, often overhanging spinnerets (e.g., figs. 203, 249, 279); grayishochre, often with darker spots, whose num- ber varies widely even within species. Male gonopore with four epiandrous spigots in all species examined ( M. argentinensis   , rica   , blanda   , delicata   , uvita   , maldonado   ; figs. 113–118). ALS usually with several (5–6) piriform gland spigots (examined: M. argentinensis   , rica   , blanda   , globulosa   , maldonado   ; figs. 146–150), with only one piriform gland spigot each in M. delicata   and uvita   (fig. 175); other spinnerets typical for family.

Sexual dimorphism slight, females with shorter legs, unmodified clypeus and chelicerae, with greater variation in opisthosoma size and shape. Epigynum ranging from extremely inconspicuous (same pale color as opisthosoma) to dark-brown rugose plates (e.g., figs. 223, 270); internally with dorsal pore plates in various configurations (e.g., figs. 216, 224, 248); uterus externus often with complex system of sclerotized ducts ventrally (figs. 218, 225, 255, 262, 278, 290; receptacles?), often asymmetric.

MONOPHYLY: All species included share the globular bulb with tubular embolus ending in a spine, with no other projection; most species share the ventral hinged process on the male procursus, the dorsal attachment of the bulb to the cymbium, and a complex system of sclerotized ducts in the female internal genitalia. See Specific Relationships, group 3 below, for species that lack these characters; they are nevertheless assigned to the genus for their striking general similarity.

GENERIC RELATIONSHIPS: The genus is apparently more closely related to some Old World genera (the Pholcus   group sensu Huber, 1995), than to other New World genera (tubular membranous embolus, globular hairs on male chelicerae with deep parallel grooves). Several other similarities to Old World genera, however, like small PME-ALE distance, capsulate tarsal organ, absence of palpal coxal apophysis and thoracic groove, and presence of ALS piriform gland spigots and epiandrous spigots, seem to be plesiomorphies.

SPECIFIC RELATIONSHIPS: The genus can be tentatively divided into five operational species groups, at least some of which are possibly monophyletic: (1) The group including the type species, most diverse in southern Brazil, but apparently ranging from central Argentina to Ecuador; with two possible synapomorphies: bifid opisthosoma and sclero- tized dark epigynum; including: M. argentinensis   , bicornis (Keyserling)   , bifida Simon   ,? duodecimpunctata Schmidt,? flavipes Schmidt, heraldica Mello-Leitão   , quadrifasciata Mello-Leitão   , strinatii (Brignoli)   (see Remark below), and the new species nadleri   , n. sp., bonaldoa   , n. sp. (2) The group previously assigned to Micromerys   (transferred by Huber, 1997a), ranging from Mexico to southern Brazil; often with cylindrical opisthosoma, usually very small (total length ~ 2 mm), male clypeus not or only slightly modified, with frontal cheliceral apophyses as possible synapomorphy; including: M. delicata   , uvita   , talamanca Huber,? unicolor (Keyserling)   , mariguitarensis   González- Sponga, and the newly described M. beni   , n. sp.; I have seen further undescribed material from Brazil, Ecuador, Bolivia, Colombia, and Guyana. (3) A group represented in this paper by four newly described species ( M. tingo   , n. sp.; taruma   , n. sp.; samiria   , n. sp.; maldonado   , n. sp.), ranging from Bolivia and Peru to Guyana (map 1) (possibly including M. auberti Caporiacco   from French Guiana); with complex procursus that lacks a hinged process, without sclerotized ducts in the female internal genitalia, with prolaterally attached bulb. All these characters are plesiomorphies, and the group is possibly a paraphyletic assemblage of primitive species. However, the reduction of globular hairs on the male chelicerae may constitute a synapomorphy of this group. (4) The group including all Central American species and the four known island species (see Distribution below), ranging from Mexico to northern Brazil; very similar to group 1, but opisthosoma not bifid, epigynum not sclerotized, male palpal femur without ventral apophysis; including the 45 Central American species in Gertsch (1986), plus M. lancetilla Huber   , reventazona Huber, toro Huber, hondura Hub- er, hitoy Huber, asintal Huber   , bellavista Gertsch and Peck   , reederi Gertsch and Peck, debrasi Pérez González and Huber   , and possibly lingua (Schmidt) and conica (Simon)   . I have seen further undescribed material from Colombia and Brazil (Manaus). This group is possibly not monophyletic. (5) A group so far only represented by the newly described M. furcata   , n. sp., from southeastern Brazil and the very aberrant M. globu- losa from Peru and Bolivia (the AMNH has females from Trinidad that appear closely related to M. globulosa   !), with globular opisthosoma and relatively short legs. This group is possibly close to, or nested within group 2 ( M. furcata   has cheliceral apophyses!).

REMARK: In the original description of Metagonia strinatii (Brignoli) (Brignoli, 1972a)   , the female internal genitalia (Brignoli’s fig. 9) are simple and symmetric, while those of ‘‘ Priscula cf. paeta   ’’ have asymmetrical internal sclerotized ducts (Brignoli’s fig. 13). The two figures were obviously mixed up.

MISPLACED SPECIES: When New World ‘‘ Micromerys   ’’ species were transferred to Metagonia (Huber, 1997a)   , Micromerys occidentalis (Mello-Leitão, 1929)   was the only species not examined. I have since seen the female holotype (from Tapera, Pernambuco, Brazil; date and collector not given, in MNRJ), which is obviously a Micropholcus fauroti (Simon, 1887)   (NEW SYNONYMY), a pantropical pholcid (Deeleman and Prinsen, 1987; Pérez González, 1995).

NATURAL HISTORY: Most species (for which these data are known) have been collected either in caves (mainly in Mexico) or from the undersides of leaves ( Gertsch , 1986; Huber , 1997a). The only easy way to collect them in reasonable numbers seems to be by hand (turning over leaves, or picking them from cave walls), which may be the reason for the relatively poor representation of the genus in the collections I have seen. (Gertsch, when revising the genus, had eight specimens from four species from Costa Rica available for study, collected traditionally by sweeping of foliage; during my own work in Costa Rica I collected with little effort about 350 specimens from eight species, usually at the rate of about one specimen per minute, all by hand). Only one species ( M. rica Gertsch   ) has been studied in some detail with respect to prey capture, courtship, copulation, egg sac production, and genital mechanics (Huber, 1997a)   .

DISTRIBUTION: From Mexico to central Argentina. The only record for the USA (Texas) is from a single individual in a banana bunch from Mexico. The genus is conspicuously absent on the Antilles, with the exception of two eyeless troglobites ( M. debrasi   on Cuba, M. jamaica   on Jamaica). The only other is- land species are two more eyeless troglobites on Galápagos ( M. bellavista   , reederi).

COMPOSITION: The genus now includes a total of 79 nominal species. Judging from the undescribed species I have seen in the few collections studied, a comprehensive revision would probably yield at least several dozens of new species in South America.

Kingdom

Animalia

Phylum

Arthropoda

Class

Arachnida

Order

Araneae

Family

Pholcidae