Rogeria species groups

Kugler (1994. A revision of the ant genus Rogeria with description of the sting apparatus (Hymenoptera: Formicidae). J. Hym. Res. 3: 17-89) organized Rogeria species into groups, stating "Some species can be assembled into more or less distinct species groups. Others can not be placed easily in any group, or seem to link several groups. These incertae sedis species are described with the group to which they may be most related." The diagnostic characters of these groups can be helpful in making species determinations.

The explanation and diagnostic details of the species group arrangements are prefaced by the following:

The stigmatica-group may be distinct enough to be treated as a separate genus, but for now seems tied to the rest of Rogeria through Rogeria blanda.

In the creightoni species group, extensive variation and often limited and scattered collections made it difficult to ascertain which specimens were simple variants and which were distinct species. At one time or another, I considered recognizing between four and 20 species in this group. Ultimately, I tried to steer a middle course between these extremes; neither masking the variation by describing large conglomerate species, nor encumbering the genus with a lot of dubious new species names. As a result, I have been somewhat more venturesome about naming new species in this group, yet there remain a number of rather heterogeneous species (Rogeria alzatei, Rogeria brunnea, Rogeria creightoni, Rogeria leptonana). I have described and illustrated some of the variants in these heterogeneous species in order to alert other taxonomists to remaining species problems and the need for extensive collecting, especially in the Caribbean Islands and circumcaribbean countries.

In the diagnoses below, if a species is listed as undissected, the palpal formula, pygidium, and sting apparatus characters are unknown.

stigmatica-group

Diagnosis. —(prominula and megastigmatica not dissected). WL 0.67-1.30mm. Palpal formula 3,3 or 3,2. Eye with 4-41 facets. Metanotal groove distinct and extends down sides of mesosoma. Petiolar peduncle without a keel and inferior process a small step or absent. Nodes and gaster wide. Gaster with terminal segments not rotated ventrad, or only slightly rotated (besucheti). No pygidial gland sculpture or any evidence of reservoirs. Sting apparatus: weakly sclerotized, spiracle occupying more than 1/4 of spiracular plate; no anal plate; valve chamber not arising abruptly from base sting shaft; sting shaft and lancets weak, spatulate (except perhaps for prominula); sting shaft apex without any flange; furcula a simple arch (no dorsal arm). Predominantly dense areolate macrosculpture on head (except middorsum), mesosoma (except some stigmatica), and nodes. Mandibles with piligerous punctures and stronger, more extensive carinulate sculpture than in other Rogeria species. No microsculpture on most of body. Body of clypeus with a median erect hair low near anterior margin.

Similar incertae sedis species: Rogeria blanda. This species has sculpture and pilosity like ciliosa and gibba, but has a 2,2 palpal formula, weak metanotal groove, dentate inferior petiolar process, and gaster, pygidium and sting apparatus typical of other groups.

scandens-group

Diagnosis. —(terescandens not dissected). WL 0.78-1.17mm. Palpal formula 3,2 Eyes large (30-80 facets). Propodeal spiracle faces strongly caudad. Metapleural lobes prominent, triangular. Petiolar node low, anterior face indistinct from peduncle (except some subarmata). Inferior petiolar process dentate. Postpetiolar sternum large. Pygidial gland sculpture and reservoirs present, at least in subarmata. Sting apparatus like that of inermis (Fig. 42). Head, mesosoma, and nodes predominantly rugose; sides of head below eye smooth. Dorsa of head, mesosoma nodes, and gaster T1 with sparse, stiff, untapered, erect hairs and sparse, inconspicuous appressed pilosity (occasional decumbent hairs in some subarmata). Scapes and legs with appressed hair only.

Similar incertae sedis species: Rogeria procera, Rogeria tonduzi. These both lack the stiff hairs and inflated postpetiole that make the group so distinctive, but otherwise are so similar that perhaps they should be included.

germaini-group

Diagnosis. —WL 0.65-1 .05mm, usually > 0.80mm. Mandibles triangular. Palpal formula 3,2. Body of clypeus not projecting over apron. Eye small (6- 20 facets; OI 0.09-0.14). Propodeal spines rather long (PSI 0.18-0.23); directed caudad. Petiole with prominent keel and dentate inferior process. Petiolar node rises abruptly from anterior peduncle and with more or less distinct anterior, dorsal and posterior surfaces. Posterior two-thirds of postpetiolar node with parallel or slightly convergent sides. Postpetiolar sternum in side view rather long, its anterior corner perpendicular. Pygidial gland sculpture and reservoirs present. Sting apparatus similar to that of inermis, but sting shaft and lancets weak; lancet lacks barbule. Laterodorsa, sides, and posterior head rugose-areolate (sometimes effaced on sides). Mesosoma predominantly rugose or vermiculate-rugose. Microsculpture weak; intervals on head and mesosoma shiny and nearly smooth. Mesosoma dorsum and gaster Tl with abundant fine, tapered, erect-suberect hairs, but very little, if any, decumbent or appressed pilosity.

Similar incertae sedis species: Rogeria pellecta, Rogeria sicaria (sicaria not dissected) These have different petiole shapes and more decumbent hair on the mesosoma. Rogeria sicaria also differs in clypeus, propodeal spines, and erect pilosity.

creightoni-group

Diagnosis.— (brunnea, nevadensis, and tribrocca not dissected). WL 0.51-0.93mm. Mandibles triangular, except as noted. Palpal formula 3,2 or 2,2. Eyes small (6-19 facets). Petiole with a distinct node and dentate inferior process. Pygidial gland sculpture and reservoirs present. Sting apparatus like that of inermis unless otherwise noted. Mesosoma predominantly rugose or carinate. Head dorsum, mesosoma, nodes, and gaster covered with two distinct kinds of hairs: 1) short, decumbent pilosity and 2) equally or less abundant longer, erect-suberect hair (except for lack of erect hair on head of some scobinata.). Usually more than 10 pairs on mesosoma dorsum (9 in some leptonana, 8 in carinata) and 2 or more posterodorsally projecting hairs on each node. All hairs tapered.

Similar incertae sedis species: Rogeria inermis, Rogeria belti, Rogeria cornuta, Rogeria neilyensis, Rogeria exsulans (cornuta and neilyensis not dissected). These do not have two distinct types of hair on the mesosoma dorsum.

curvipubens-group

Rogeria cuneola
Rogeria curvipubens

Diagnosis.—WL 0.50-0.63mm. Mandibles triangular. Palpal formula 2,2. Clypeal apron usually convex (medially flattened in Haitian curvipubens). Eye small (4-11 facets). PSI 0.13-0.18. Petiole with distinct node, weak keel, and dentate inferior process. Postpetiole from above usually as in Fig. 74. Pygidial gland sculpture and reservoirs present. Sting apparatus as in inermis (Fig. 42), except for sting shaft and lancets of curvipubens. Median head and cheeks with weak longitudinal rugose-areolate macrosculpture. Mesosoma with predominantly rugose macrosculpture and areolate microsculpture, both often weak. Body covered with appressed-decumbent pilosity. Erect hairs sparse: none on scapes or extensor surfaces of legs, 0-16 on head (if present, short and limited to posterior head), usually 2-7 pairs on mesosoma dorsum (rarely 8), 0-1 pair posterodorsally projecting and 0-1 laterally projecting hairs on each node. Anterior portions of gaster Tl often lack erect hair. All hairs tapered.

Similar incertae sedis species: Rogeria micromma, Rogeria minima (neither dissected). Rogeria micromma has a subrectangular postpetiole in dorsal view and abundant erect hair on head. Rogeria minima has stiff, cuneate hairs and a 2,1 palpal formula.

foreli-group

Rogeria bruchi
Rogeria foreli

Diagnosis.—WL 0.50-0.80mm, usually < 0.75mm. Mandibles triangular. Palpal formula 2,2. Eye 5-20 facets. Propodeal spines wide at base. Petiole with distinct node and dentate inferior process. Pygidial gland sculpture and reservoirs present. Sting apparatus almost identical to that of inermis (Fig. 42). Sculpture predominantly microareolate on head, mesosoma, and waist; macrosculpture feeble and limited to head. Most of body with short, appressed-decumbent pilosity only. Erect-suberect hairs present on mandibles, clypeus, ventral head, coxae, trochanters, sterna of gaster, and terminal terga of gaster.