Strumigenys ananeotes Longino & Booher, 2019

Booher, Douglas B., 2021, The ant genus Strumigenys Smith, 1860 (Hymenoptera: Formicidae) in western North America North of Mexico, Zootaxa 5061 (2), pp. 201-248 : 218-221

Strumigenys ananeotes Longino & Booher, 2019

Figure 36

Distribution. USA; Utah.

Type material: Holotype worker: USA, Utah, Salt Lake Co.: Salt Lake City, 40.77100 -111.85419 ± 20 m, 1410 m, 13–14 Aug 2018, urban garden, nest in soil (J. Longino #10240), unique specimen identifier (casent0645955)[ CAS].

Paratypes: Paratype workers, alate queens: same data as holotype, unique specimen identifiers for workers; (casent0645954) [ UMNH], (casent0645956) [ MCZC], (casent0645957) [ USNM], (casent0645965) [ JTLC], (casent0648042) [ BYU], (casent0799940) [ UGCA], (casent0799942) [ UGCA], and for queens (casent0799941) [ UGCA], (casent0799943) [ JTLC] .

Worker measurements (holotype and paratypes n=6): HL = 0.524 –0.554 (0.544); HW = 0.388 –0.398 (0.393); ML = 0.09–0.102 (0.097); PW = 0.254 –0.271 (0.265); SL = 0.275 –0.306 (0.288); FL = 0.342 –0.356 (0.352); HT = 0.279 –0.303 (0.289); EL = 0.039 –0.047 (0.043); WL = 0.544 –0.572 (0.554); CI = 71–75 (72); MI = 16.3–18.4 (17.5); SI =70–76 (73).

Queen measurements (n=1): HL = 0.587; HW = 0.423; ML = 0.103; PW = 0.344; SL = 0.304; FL = 0.396; HT = 0.316; EL = 0.113; WL = 0.665; CI = 72; MI = 17.6; SI = 72.

Diagnosis (adapted from Longino & Booher 2019). Strumigenys ananeotes can be distinguished from all other North American species by tooth morphology and clypeal pilosity. In some specimens of S. ananeotes , the basalmost tooth is small or missing, which gives a count of eight or seven teeth of alternating sizes. The setae on the anterior margin of clypeus between the mandibles are dorsoventrally directed translucent spoon-shaped setae with irregularly scalloped apical borders. Strumigenys ananeotes shares similar dentition with three other Nearctic species that have principal teeth alternating between large and small pointed teeth: midwestern species S. lucky , and eastern species S. metazytes ( Bolton, 2000) and S. hyalina ( Bolton, 2000) . Strumigenys metazytes has only three larger principle teeth flanked by smaller teeth. Strumigenys lucky and S. hyalina have four larger teeth flanked by smaller teeth as does S. ananeotes but the larger teeth decrease in size such that tooth seven (the fourth of the large teeth) is only about half the length of first large tooth; in S. ananeotes tooth seven is only slightly smaller than tooth one. Strumigenys lucky and S. hyalina also differ in the shape and orientation of setae on the anterior margin of the clypeus between mandible insertions. In S. hyalina , these setae are translucent and spoon-shaped but have evenly flat apical margins; in S. lucky they are opaque, more narrowly expanded, and evenly rounded or pointed apically. Of western species, S. ananeotes is most similar to S. chiricahua , but in S. chiricahua , the first three teeth increase in size and do not completely overlap when the mandibles are closed, whereas in S. ananeotes the large teeth overlap the opposing smaller teeth when the mandibles are closed. The only other USA species with similar mandibular teeth is the introduced species S. margaritae Forel, 1893 , which also has teeth that alternate in size, but the smaller teeth are blunt and not pointed as in S. ananeotes . However, in other characters S. margaritae bears little resemblance to S. ananeotes .

Description of worker. Mandibles with a short diastemmic gap, when measured from margin of clypeus to the first tooth, the gap is longer than the length of the first tooth. Basal lamella broadly and evenly triangulate with slightly concave free sides. Mandibles with seven or eight main teeth alternating between similarly sized long and short teeth (if eight then basalmost tooth is an additional small tooth). These teeth followed by five minute denticles and ending apically with a small tooth. In closed position long teeth overlap short teeth of opposite mandible. Eyes well developed with 7–10 ommatidia.

Maximal width of clypeus 1.1–1.3 times length. Free margins of clypeus smooth, broadly and evenly rounded, with outline only obscured slightly by heavily punctate sculpture.

Pronotum and mesonotum are broadly rounded in profile. In profile view, metanotal groove is apparent and broadly impressed. The mesonotum is raised above groove and forms a step down to the propodeum. Some paratypes have a sharply raised transverse ridge at the anterior dorsal border of the mesonotal groove that interrupts outline. Propodeal teeth triangular, directed posteriorly and only slightly longer than lamellae that subtends teeth, which evenly follows declivitous face of the propodeum and is nearly equal in width along its length. Bulla of propodeal spiracle large (0.031 –0.042 in widest length) and directed posteriorly. Bullae of femoral glands apparent on all femora and oval in shape, positioned at a distance to apex that is equal to or less than length of the bulla.

Sculpture. Head and clypeus densely punctate to reticulopunctate except for a small area of the frontal triangle. Similar sculpture on the dorsum of mesosoma, dorsal half of the declivitous face of the propodeum, and dorsal node of petiole. Side of mesosoma with punctate sculpture peripherally, but otherwise smooth and shining. Disc of postpetiole free of sculpture and shining. Bulla of metapleural gland heavily reticulopunctate with a band connecting sculpture to propodeal spiracle. The rest of the side of propodeum smooth and shining. Gaster with basigastral costulae prominent and extending approximately one quarter of the length of the first gastral tergite, otherwise smooth and shining.

Pilosity. Ground pilosity of head consisting of simple to clavate erect setae that curve towards the midline of head, these setae on head being more expanded towards the clypeus. Dorsum of clypeus with similar setae but smaller than those along anterior margin. Anterior fringe of setae of clypeus with most setae curving ventrally and/or towards the midline of clypeus. A pair of much smaller setae between the mandibles curve ventrally and somewhat away from the midline. In some individuals a single seta or pair of outer neighboring setae also curve ventrolaterally away from midline. Setae along anterior margin of scape clavate with at least one pair curving towards the base; additional numerous simple setae of similar or shorter length also present on scape. Two pairs of elongate differentiated flagellate setae present on head, one pair at apicoscrobal region and one pair straddling the midline near posterior margin of head.

Ground pilosity of mesosoma sparse, consisting of simple short curved reclinate setae. Differentiated elongate flagellate setae present singly on each humeral angle, as a pair on dorsum of pronotum between humeral setae, and as a pair on the dorsal surface of mesonotum. Two pairs of similar elongate flagellate setae present on petiole and postpetiole and are numerous on gastral tergites. First gastral tergite with short appressed to subappressed setae lateral to the medial pairs of flagellate setae. Legs with numerous short reclinate simple setae. A single differentiated elongate flagellate seta present on meso- and meta-tibia, meso-basitarsi, and two setae on meta-basitarsi.

Spongiform appendages. Spongiform appendages present on lateral and posterior surfaces of petiolar node, as an irregular flange along the ventral surface of petiole, as a ventral lobe on postpetiole and as a narrow flange on dorsal anterior surface of postpetiole that connects to a broad flange on lateral and posterior surfaces of postpetiole.

Description of queen. Other than typical queen morphology e.g., wings and enlarged mesonotum, queens are similar to workers. The most apparent morphological differences are larger size (see queen measurements above); larger eyes (eyes with 45–50 pigmented ommatidia); wider petiolar node (1.5–1.8 times wider than long in workers and>2 times wider in queen); and a spiracle present on anterior of metapleural gland bulla (absent or inconspicuous in workers).

Comments. Longino & Booher (2018) provided a diagnosis but no measurements or description, anticipating doing this in a more thorough treatment. Measurements and a full description are provided here. There are now two collections of this species, the type series and a second collection <1km from the first. The type series was collected by myrmecologist J.T. Longino in his back yard garden in an urban area of Salt Lake City, Utah. On the evening of August 13, 2018, Longino found four workers foraging on the soil surface at night in his raised garden bed. The following night he sifted through several layers of soil to a depth of about 10 cm collecting a total of 66 workers (some carrying larvae), and six alate queens. The presence of alates in this August collection predicts mating flight phenology similar to observed native eastern species that produce sexuals in late summer that disperse from late summer through fall (Duffield & Alpert 2012). Also collected in the vicinity were other ant species Tetramorium immigrans Santschi, 1927 , Brachymyrmex depilis Emery, 1893 , Solenopsis molesta ( Say, 1836) , and Formica neoclara Emery, 1893 ( Longino & Booher 2019). The name S. ananeotes , meaning newly emerged, reflects the unintended stewardship of this species provided by urban irrigation of green spaces, which may increase preferred moist environments for Strumigenys and their springtail prey ( Blackith & Blackith 1975). A second collection was made by Tobias Hays, a University of Utah student, under some paving stones in a nearby neighborhood (J. Longino, pers. com.).

Figures

FIGURE 36. Holotype worker of Strumigenys ananeotes [CAS: casent0645955]. Photographed by Michele Esposito (AntWeb 2021).