Triaeris Simon

Platnick, Norman I., Dupérré, Nadine, Ubick, Darrell & Fannes, Wouter, 2012, Got Males?: The Enigmatic Goblin Spider Genus Triaeris (Araneae, Oonopidae), American Museum Novitates 2012 (3756), pp. 1-36 : 6-22

Triaeris Simon

Triaeris Simon, 1891: 561 (type species by monotypy T. stenaspis Simon ).

DIAGNOSIS: Members of this genus have notably elongated, ventrally spinose patellae on leg I (figs. 17, 37), a feature that is shared with a group of undescribed genera from West Africa. The males assigned below to Triaeris can easily be separated from those of the undescribed groups by several unique modifications, including the leaf-shaped setae on the palpal patella (figs. 74, 107), the enlarged, subdistal seta on the labium (figs. 70, 86), and the pair of enlarged setae near the anterolateral corners of the sternum (figs. 70, 89, 90, 126); they also differ in having a simple embolus without accessory structures (figs. 73, 105). The females assigned below to Triaeris show a wide range of genitalic structures, but differ from those of the undescribed genera in having hypertrophied posterior genitalic elements, which occupy most of the postepigastric scutal area and involve external modifications of that scutum (figs. 31, 32). The notably elongated seta found in both sexes on the anterior surface of each cheliceral paturon (figs. 4, 6, 83, 84, 110, 111) may also be unique to Triaeris .

GENDER: The gender of the name Triaeris has been controversial; Bonnet (1959), for example, regarded the name as masculine. That view was disputed by Brignoli (1974: 209), who indicated that:

Some doubt may arise concerning the genus [sic, lapsus for gender] to be attributed to the name Triaeris ; in my opinion, the etymology is clear: Tris + aeris i.e. “with three parts of copper”; in practice, an apposition. Berland has taken it as masculine and has described T. macrophthalmus ; according to me, by analogy with other names again created by Simon, such as Xestaspis, Anasaspis , Coryssocnemis , etc., it sounds better in the feminine (the noun aranea being understood).

Our colleague H. Don Cameron has kindly indicated that Brignoli’s etymology is erroneous, reflecting an accidental similarity. Simon consistently followed a 19th-century grammar school convention to differentiate a long “e” from a short “e” by spelling the long “e” as “ae.” To distinguish the Latin words levis (“light,” short e) from lēvis (“smooth,” long e), for example, Simon spelled smooth as laevis. Thus, Triaeris is properly spelled Triēris in standard Latin (and without the macron, to accord with the Code, Trieris). Simon’s original spelling of the generic name is of course protected by the Code, but the gender is determined by the correct Latin spelling. The word triēris is a two-ending Latin adjective meaning “having three banks of oars” (e.g., the spelling is triēris for masculine or feminine, triēre for neuter). Simon’s type species, T. stenaspis , does not solve the problem since stenaspis is also a two-ending adjective (meaning “having a narrow carapace”). So Triaeris should be treated as masculine under ICZN Art. 30.1.4.2, which specifies masculine as the default gender in such cases.

DESCRIPTION: Total length of males 1.3–1.6, of females 1.2–2.3. Cephalothorax: Carapace broadly oval in dorsal view, anteriorly narrowed to about half its maximum width, pars cephalica domed in lateral view in males, strongly elevated in females, anterolateral corners with strongly sclerotized, triangular extension in males, surface of elevated portion smooth (figs. 2, 81, 108), surface of sides smooth (fig. 82, 109) or finely reticulate (fig. 3), pars thoracica with rounded posterolateral corners, posterolateral edge without pits, posterior margin not bulging below posterior rim, posterolateral surface without spikes, depressions, radiating rows of pits, or fovea (but longitudinal dark stripe sometimes present on foveal area), lateral margin straight, rebordered, without denticles; plumose setae near posterior margin of pars thoracica absent; marginal, nonmarginal pars cephalica, pars thoracica setae all dark, needlelike. Clypeus low, ALE separated from edge of carapace by their diameter or less, often by their radius or less; margin slightly to strongly rebordered (figs. 4, 83, 110), curved downwards in front view, vertical in lateral view, median projection absent; setae dark, needlelike; chilum absent. Eyes six, well developed, ALE oval, PME squared, PLE oval; posterior eye row recurved from above, usually procurved from front; ALE usually separated by their radius to diameter, ALE-PLE separated by less than ALE radius, PME touching throughout most of their length, PLE-PME separated by less than PME radius. Sternum longer than wide, uniform, not fused to carapace, median concavity absent, with radial furrows between coxae I–II, II–III, III–IV (figs. 5, 117), furrow smooth, radial furrow opposite coxae III absent, surface smooth, without pits, microsculpture absent, sickle-shaped structures absent, anterior margin with continuous transverse groove in males, posterior margin extending posteriorly beyond anterior edges of coxae IV as single extension, anterior corner with strongly sclerotized triangle in males, lateral margin with infracoxal grooves bearing anterior, posterior openings, distance between coxae approximately equal, extensions of precoxal triangles present, lateral margins with narrow extensions between coxae, without posterior hump; setae sparse, dark, needlelike, densest laterally, originating from surface, without hair tufts; males with pair of enlarged, posteromedially directed setae situated near anterolateral corners (figs. 89, 90, 126). Chelicerae straight, anterior face unmodified; promargin with one broad tooth, retromargin at least sometimes with numerous denticles (fig. 113); fangs without toothlike projections, directed medially, shape normal, without prominent basal process, tip unmodified (figs. 7, 85, 112); setae dark, needlelike, densest medially; paturon inner margin with scattered setae, distal region unmodified, posterior surface unmodified, promargin with row of flattened setae, inner margin unmodified, laminate groove absent; at least in T. stenaspis and T. ibadan , one seta on anterior surface of paturon greatly elongated, reaching more than half of paturon length (figs. 4, 6, 83, 84, 110, 111). Labium in males rectangular, not fused to sternum, posterior margin with unsclerotized area around midline, anterior margin indented at middle, much more heavily sclerotized than sternum, subdistal portion with enlarged seta (fig. 86); in females more triangular, slightly indented at middle, with few distal setae (figs. 8, 114). Endites in males distally excavated, serrula absent (figs. 87, 88), much more heavily sclerotized than sternum, with narrow translucent band separating greatly enlarged anterior portion from short posterior portion, posterior portion fused with labium at its posterolateral corners (figs. 86, 87); in females distally not excavated, serrula present in single row (figs. 9, 10, 115, 116). Female palp without claw or spines; patella without prolateral row of ridges; tibia with two or three trichobothria (figs. 30, 121); tarsus not expanded (figs. 28, 29, 119, 120). Abdomen: Cylindrical, without long posterior extension, rounded posteriorly, interscutal membrane without rows of small sclerotized platelets; dorsum soft portions white, without color pattern. Book lung covers large, ovoid, without setae, anterolateral edge unmodified; posterior spiracles not connected by groove. Pedicel tube short, unmodified (fig. 11), scutopedicel region unmodified, scutum extending far dorsal of pedicel, plumose hairs, matted setae on pedicel area absent, cuticular outgrowths near pedicel all absent. Dorsal scutum strongly sclerotized, without color pattern, usually covering most of abdomen length, more than half of abdomen width, not fused to epigastric scutum (fig. 1), middle surface smooth, sides smooth, anterior half without projecting denticles. Epigastric scutum weakly sclerotized, surrounding pedicel, not protruding, small lateral sclerites absent, without lateral joints in females. Postepigastric scutum weakly sclerotized, short, only around epigastric furrow in females, longer, fused to epigastric scutum in males, anterior margin unmodified, with posteriorly directed lateral apodemes only in some females. Spinneret scutum present, incomplete ring, with fringe of stout setae. Supraanal scutum absent. Dorsal, epigastric, postepigastric setae dark, needlelike. Dense patch of setae anterior to spinnerets absent; interscutal membrane with setae. Spinnerets (scanned in T. stenaspis and T. ibadan ): anterior, posterior laterals bisegmented, PMS unisegmented (figs. 12, 92, 122); anterior laterals with one major ampullate gland and three piriform gland spigots in males (fig. 93), two or three in females (figs. 13, 123), posterior medians with two spigots in males (fig. 94), five in females (figs. 14, 124), posterior laterals with four spigots in males (fig. 95), six or seven in females (figs. 15, 125); colulus represented at least by pair of setae. Legs: Femur IV not thickened, same size as femora I–III; patella I elongated, measured dorsally, almost as long as tibia I (figs. 16, 17), other patellae also elongated but less dramatically (fig. 18); patella plus tibia I about as long as carapace; tibia I unmodified, tibia IV without ventral scopula or specialized hairs on ventral apex, metatarsi I, II mesoapical comb absent, metatarsi III, IV weak ventral scopula absent. Leg spines present on patella I (and sometimes II), tibia I, II, IV, spines longer than segment width. Superior tarsal claws (scanned in T. stenaspis and T. ibadan ) with three or four large, basally situated teeth on outer surface, those of legs I, II with several smaller, distally situated teeth on inner surface, those of legs III with fewer, larger teeth on inner surface, those of legs IV elongated, with only one large tooth (or none) on inner surface (figs. 19–26, 96–99); claws on legs III, IV accompanied by modified setae with clawlike tips (figs. 21, 22, 25, 26, 98, 99); inferior claw absent. Trichobothrial base ridged (fig. 27). Tarsal organ with three receptors on legs I, II, two receptors on legs III, IV, palps (figs. 100–104; Platnick et al., 2012a: figs. 11–15). Genitalia: Male epigastric region with sperm pore small, oval, situated between anterior and posterior spiracles, unmodified (fig. 91); furrow without Ω-shaped insertions or setae. Male palp of normal size, not strongly sclerotized, right and left palps symmetrical; embolus light, prolateral excavation absent; trochanter normal size, unmodified; femur normal size, two or more times as long as trochanter, without posteriorly rounded lateral dilation, attaching to patella basally; patella shorter than femur, not enlarged, without prolateral row of ridges, with group of prolateral leaf-shaped setae (figs. 74, 107); tibial trichobothria not examined; cymbium narrow in dorsal view, fused with bulb proximally but with clearly defined seam between, extending beyond distal tip of bulb, plumose, stout setae absent but distal patch of setae present; bulb shorter than cymbium, slender, elongated; embolus a short, simple process (figs. 105, 106). Female genitalia complex, posterior elements hypertrophied, involving external modifications of postepigastric scutum (figs. 31, 32, 118), anterior receptaculum relatively small (fig. 33).

DISTRIBUTION: Aside from the pantropical type species, the genus is known only from West Africa .

INCLUDED SPECIES: Of the various names currently assigned to Triaeris (see Platnick, 2012, for a listing), only T. stenaspis and its synonyms actually belong to the genus. Of the other African species, T. equestris (from Príncipe) belongs to a different genus in the Triaeris subgroup, whereas T. macrophthalmus (from Kenya and Zanzibar) belongs to a different genus in the Zyngoonops group. The various taxa from outside of Africa are wildly misplaced.

Key to Species

1. Males (known only in T. togo and T. ibadan ).............................................................................2

– Females.............................................................................................................................................3

2. Legs and palps patterned (fig. 129); palpal patella with relatively few leaf-shaped setae (fig. 107).................................................................................................................................. ibadan

– Legs and palps without color pattern; palpal patella with many leaf-shaped setae (fig. 74). ...................................................................................................................................................... togo

3. Posterior receptaculum a wide triangle (figs. 33, 39, 40)............................................ stenaspis

– Posterior receptaculum otherwise................................................................................................4

4. Posterior receptaculum long, narrow throughout its length (figs. 46, 53).............................5

– Posterior receptaculum otherwise................................................................................................6

5. Posterior receptaculum with long, squiggled posterior duct (figs. 52, 53)....................... fako

– Posterior receptaculum with short posterior duct (figs. 45, 46)....................................... moca

6. Posterior receptaculum with darkened, parallel sides (figs. 57, 59)................................... oku

– Posterior receptaculum otherwise................................................................................................7

7. Posterior receptaculum with leaf-shaped sides (figs. 64, 66).................................... menchum

– Posterior receptaculum otherwise................................................................................................8

8. Legs patterned (fig. 129); posterior receptaculum with triangular posterior invagination (figs. 133, 134)....................................................................................................................... ibadan

– Legs without color pattern; posterior receptaculum with median, external slit (figs. 76–80).. ...................................................................................................................................................... togo