Adelomyrmex Emery

Fernández, F., 2003, Revision of the myrmicine ants of the Adelomyrmex genus-group (Hymenoptera: Formicidae)., Zootaxa 361, pp. 1-52 : 8-13

Genus Adelomyrmex Emery

Adelomyrmex Emery , 1897:590. Type species: Adelomyrmex biroi Emery , 1897 (monobasic). Kempf, 1972:18 (Checklist of Neotropical species). Bolton, 1994:106 (Preliminary tribal assignment). Bolton, 1995:58 (World catalog).

Apsychomyrmex Wheeler , 1910:261. Type species: Apsychomyrmex myops Wheeler (monobasic). Emery, 1922:268; Smith, 1947: 468-473 (partial revision). Kempf, 1972:18 (as junior synonym of Adelomyrmex ).

Arctomyrmex Mann , 1921:457 (as subgenus of Adelomyrmex (sensu lato)). Type species: Adelomyrmex hirsutus Mann (monobasic). Brown, 1973:178 (provisional junior synonym of Adelomyrmex ). Bolton 1994:106 (synonymy confirmed).

Adelomyrmex includes some of the least known myrmicine ants, which are rare in insect collections. The queen was unknown to date in the New World, and the male was unknown to date in the World. Little of the way of life of the species is known.

Notes about synonymy and taxonomic history. The myrmicine ant genus Adelomyrmex was previously known from the Neotropical and Oriental Regions, with 12 species ( Fernández & MacKay, 2003). The Neotropical species were formerly in the genus Apsychomyrmex (described by Wheeler in 1910), with the sole species Apsychomyrmex myops , based on a single worker from Guatemala. Menozzi (1931) described two new species, A. silvestrii and A. tristani , from Guatemala and Costa Rica respectively. Smith (1947) offered a synthesis of the systematics, way of life and geographical distribution of this genus, redescribing taxa and expanding the known ranges of some species. In this paper, Smith (1947) suggested the possibility of the presence of Apsychomyrmex in México and South America. Kempf (1972) in his Neotropical catalogue, synonymized Apsychomyrmex and Adelomyrmex , following a suggestion of W.L. Brown, who did not provide formal justification for that proposal. Authors have followed Kempf's arrangement (i.e., Brown, 1973; Hölldobler & Wilson, 1990; Bolton, 1994, 1995). The Western Pacific islandic species Adelomyrmex hirsutus Mann and A. samoanus Wilson & Taylor were initially placed in the subgenus Arctomyrmex Mann .

Recognition. The basal mandibular tooth isolates Adelomyrmex not only from its close relative, Baracidris , but from most other myrmicines ( Perissomyrmex possesses teeth in the basal margin, but this is a very distant genus [Longino & Hartley, 1994]). In some workers of A. tristani and A. silvestrii , this tooth is hardly noticed, but this may be interpreted as secondary reduction.

Diagnosis. Adelomyrmex is defined by at least three traits postulated to be synapomorphic, that establish the putative monophyly of this taxon.

(1) Clypeal structure: elevated medially, in form of a very narrow longitudinal platform, with sharply delimited lateral borders (Figs. 9, 16, 22, 26, 47, 48, 54). From this median platform the clypeus is sloped laterally in form of a concavity each side, and in lateral view forms a ventral concavity (e.g. Fig. 15). The anterior clypeal border, in the elevated portion, is formed in some taxa as a slightly or distinctly defined bidentate projection (as in Fig. 9), the median clypeal teeth. The anterior clypeal margin possesses, in most species, a pair of teeth, one on each side of the median proyection, generally close and opposed to the teeth of the basal margin of mandibles (e.g. Figs. 9, 22, 29), the lateral clypeal teeth.

(2) Number and disposition of the clypeal setae: one apical (sometimes replaced with a pair of apical setae), which is projected laterally, and two pairs of paracarinal setae, the first pair inserted near the lateral borders of the clypeal platform and the second laterally from the sides of the clypeus (Figs. 16, 22). The clypeal area possesses other setae, but in some species, number and conformation vary among the included species. The pattern of the clypeal setae (an apical and two paracarinal setae) is constant in all species studied.

(3) Mandibles with a tooth near the proximal quarter of the basal margin. In general it is followed by a hiatus or notch of variable size (Figs. 22, 54). In most of the species these teeth are (with the closed or almost closed mandibles) opposed to the teeth of the anterior clypeal margin (the lateral clypeal teeth). Additionally, the palpal formula is 2,2 or less (Fig. 59).

Description. With character states of Adelomyrmex genus-group, modified as follows. Worker. Monomorphic, length from 1.80 to 4.2 mm. Body variously sculptured, from striate to coarsely reticulorugose. Erect or suberect setae on body, shorter and appressed on antennae and legs.

Head longer than wide, with posteriolateral corners rounded, and posterior margin slightly convex, flat, or slightly concave. Clypeus pronouncedly raised or elevated medially as a narrow longitudinal plate. Clypeus with median apical to slightly subapical seta long, projected laterad, also two lateral and two dorsal long setae posteriad apical seta. In side view clypeus concave ventrally. Anterior clypeal margin with two teeth near and opposing basal mandibular teeth. Frontal carinae distinct, closely approximated, with elongate and impressed area between them, extended to clypeal plate. Antennae 12 segmented, with 2-segmented club. Eyes relatively small, with 3 to 30 facets, situated slightly anteriad middle of head. Mandible with 4 to 7 teeth, with distinct tooth on basal margin, near to proximal quarter, in full face view opposing lateral clypeal teeth. Hypostomal tooth present, except in A. boltoni and A. longinodus . Palpal segments 2,2 or 1,1.

Promesonotum convex, without promesonotal suture. Metanotal groove distinct to indistinctly impressed. Propodeum with two spines. Propodeal spiracle round and at some distance from propodeal margin. Propodeal lobe subtriangular, rounded. Legs moderately stout, both middle and hind tibiae without spurs. Petiole distinct, campaniform to pedunculate; petiole with several ventral transverse rugae; postpetiole with conspicuous ventral transverse rugae (appearing in profile as toothlike projection).

Gaster oval (in one species with anterior angulate emarginations). Gaster smooth and shining to subopaque. Black to light brown in color. Sting large.

Queen (Fig. 42): As worker, differing from workers in the normal myrmicine queenly traits. General body size as in worker in some species. Ocelli three; anterior ocelli in fossae. Eyes with more than 120 facets. Anterior promesonotal area smooth and shining, posterior area sculptured. Most of katepisternum smooth and shining. Wings as in figure 43, densely and finely setose.

Male (previously unknown, based on A. vaderi , Figs. 43, 44). With general traits of myrmicine males. Surface sculpture: promesonotum, major areas of sides of mesosoma and gaster smooth and shining, promesonotum with several punctures; head, mesonotum, propodeum (lateral and dorsal surfaces), petiole and postpetiole irregularly rugulose, postpetiole devoid of ventral transverse carinae. Anterior border of head, and propodeal, petiolar and postpetiolar dorsum with transverse trend.

Pilosity: body abundantly setose. Head, dorsum of mesosoma, petiole, postpetiole and gaster with conspicuous suberect long setae, those of petiole and postpetiole more appressed; in full face view, several long setae oriented outward and anteriorly from clypeal area; antennae densely covered with short, decumbent setae; numerous short, erect setae on eyes; mandibles with long curved setae directed outward and forward.

Head hemispheric. Clypeus medially protuberant, convex. Frontal carinae only partially covering antennal insertions. Eyes large, globose, with numerous facets (>30 in maximum diameter). Three ocelli, prominent and sphaerical. Antennae 13-segmented, flagellomeres increasing in size from scape to apex, without evident club; scape less curved than in workers, surpassing conspicuously border of vertex. Labrum exposed. Mandibles simple, pointed. Palpal formula (in situ) 2,2. Propodeal spiracle opening shifted posteriad and laterad. Propodeum without spines. Wings (Fig. 43) densely setose, but less than in females. Petiole subcampaniform, with node evenly meeting in rounded summit, postpetiole dome-shaped.

Geographical distribution. Adelomyrmex is represented in the Neotropical Region by 23 species ranging collectively from northern México to southern Brazil and Paraguay, but absent from Chile, in the south, and from the West Indies, in the Caribbean Basin. The three species of the Old World inhabit islands (Fiji, Samoa and New Guinea) more or less near the Australian continent. Initially the genus was divided in several species-groups (e.g. Fernández & MacKay, 2003; however, a recent cladistic analysis ( Fernández, unpublished) failed to support any of these groups. Then, for time being is not desirable to propose groups until more analysis can made.

Key to the species (workers):

1 Head and dorsum of promesonotum smooth and shining (as in Figs. 57, 58, 60) ... 2

- Head and promesonotum at least partly sculptured with striae, rugulae or punctures(as in Figs. 8, 11, 23, 28, 49, 56) .................................................................. 4

2(1) Petiole with node low (Figs. 57, 64, 65); propodeal spines large (Figs. 57, 64, 65); lateral clypeal teeth absent or not visible (Fig. 58) ................................................ 3

- Petiole with node high, shorter (as in Fig. 12); propodeal spines reduced to angles; lateral clypeal teeth present; México.............................................. A. micans sp.n.

3(2) Propodeal dorsum and sides smooth; Brazil .............................. A. longinodus sp.n.

- Propodeal dorsum and sides with longitudinal rugulae; Brazil and Paraguay ........ .......................................................................................................... A. boltoni sp.n.

4(1) Most of promesonotum and first gastral tergum with coarse punctures; Old World ................................................................................................................................ 5

- Promesonotum at least partly with striae and/or rugulae; gaster without coarse punctures; New World .......................................................................................... 7

5(4) Propodeal spines large, stout (Fig. 66); New Guinea .................................. A. biroi

- Propodeal spines small (Figs. 67, 68) .................................................................... 6

6(5) Head with longitudinal striation; eyes reduced to a few ommatidia; mesosoma in lateral view as in figure 68; Samoa ...................................................... A. samoanus

- Head punctate; eyes reduced to dark spots; mesosoma as in figure 67; Fiji ........... ................................................................................................................ A. hirsutus

7(4) Mesosomal dorsum with small to large areas smooth and shining (as in Figs. 49, 56) ............................................................................................................................... 8

- Mesosomal dorsum always sculpturated througout (Figs. 11, 17, 23, 28, 39, 40) .. ..............................................................................................................................12

8(7) Propodeal spines very short, wider than long (Fig. 45); promesonotum with small to median-sized, smooth and shining central area; México and Costa Rica............ ....................................................................................................... A. brevispinosus

- Propodeal spines as long as wide or longer than wider (Fig. 51); promesonotum with a large smooth and shining area.................................................................... 9

9(8) Dorsum of head, between vertex and central area, smooth and shining and densely foveolated; Costa Rica........................................................................................ 10

- Dorsum of head never smooth and shining nor foveolate, instead reticulated or rugoreticulate .......................................................................................................11

10(9) Eyes with 7-8 ommatidia; HW> 0.50 mm; dark brown in color...... A. foveolatus

- Eyes with one ommatidium; HW <0.50 mm; light brown in color...... A. minimus

11(9) Most of side of pronotum smooth and shining (Fig. 51); hypostomal teeth large, stout (Fig. 53); eyes with 5 ommatidia; Costa Rica and Panamá....... A. laevigatus

- Sides of pronotum never with areas smooth and shining; hypostomal teeth never large or stout, eyes with two ommatida; Costa Rica............................... A. microps

12(7) Mesosoma and gaster devoid of any kind of pilosity; body with bead-like carinae; postpetiole with a strong transverse carina; México........................... A. betoi sp.n.

- Mesosoma and gaster always hairy; carinae of body not bead-like; postpetiole without strong transverse carina.......................................................................... 13

13(12) Postpetiole posteriorly overhanging gaster (Figs 13, 18); in dorsal view, gaster distinctly emarginate at base, with humeral angles; Central America....... A. silvestrii

- Postpetiole posteriorly not overhanging gaster (as in Figs. 12, 24); in dorsal view gaster without humeral angles..............................................................................14

14(13) Dorsum of mesosoma coarsely rugo-reticulate (Fig. 11).....................................15

- Dorsum of mesosoma with at least some central rugulae or costae more or less longitudinal (as in Figs. 23, 28), rarely with transverse striae (Fig. 39).............. 16

15(14) Propodeal spines pointed, higher than wide (Fig. 7); México to Colombia............ .................................................................................................................. A. myops

- Propodeal spines low, wider than high; México............................ A. mackayi sp.n.

16(14) Lateral clypeal teeth very reduced, smaller than median clypeal teeth; HW 0.44 mm or less.............................................................................................................17

- Lateral clypeal teeth larger than median clypeal teeth; HW> 0.44 mm .............18

17(16) Eyes with six ommatidia; anterior margin of clypeal plate concave; HW> 0.42; Central Andes in Colombia .......................................................... A. cristiani sp.n.

- Eyes with four ommatidia; anterior margin of clypeal plate straight; HW <0.42 mm; México to Costa Rica............................................................ A. longinoi sp.n.

18(16) HW <0.82 mm ....................................................................................................19

- HW> 0.82 mm ....................................................................................................21

19(18) Promesonotum in lateral view notably convex (Figs. 35, 37); dorsum of promesonotum with regular longitudinal striation ......................................................... 20

- Promesonotum in lateral view feebly convex (Fig. 33); typical mesosomal dorsum as in figure 23, but some as in figures 39, 40; probably a complex of species; Méx- ico to Colombia ......................................................................................... A. tristani

20(19) Promesonotum strongly convex anteriorly (Fig. 37); propodeal spines low, broader than higher (Fig. 37); Brazil ............................................. A. striatus sp.n.

- Promesonotum evenly convex (Fig. 35); propodeal spines triangular (Fig. 35); Gorgona Island in SW Colombia ................................................... A. costatus sp.n.

21(18) HW> 0.90 mm; SW Colombia ...................................................... A. grandis sp.n.

- HW <0.90 mm .................................................................................................... 22

22(21) Promesonotum with abundant erect hairs (each about 0.14 mm); body brown with appendages light brown; Eastern Andes in Colombia ....................... A. vaderi sp.n.

- Promesonotum with few to almost none erect hairs; head, mesosoma, petiole and postpetiole black with gaster and appendages dark brown; México....................... ....................................................................................................... A. robustus sp.n.