Strumigenys eggersi Emery, 1890

Silva, Thiago Sanches Ranzani Da, Chaul, Júlio Cezar Mário & Feitosa, Rodrigo Machado, 2022, Lectotype designation and redescription of four commonly collected Neotropical species of Strumigenys (Hymenoptera: Formicidae), European Journal of Taxonomy 798 (1), pp. 103-126 : 116-119

Strumigenys eggersi Emery, 1890

Figs 5–6

Strumigenys eggersi Emery, 1890: 69 .

Strumigenys (Pyramica) eggersi – Brown 1948: 110.

Pyramica eggersi – Bolton 1999: 1673.

Strumigenys eggersi – Baroni Urbani & De Andrade 2007: 128.

Diagnosis

Strumigenys eggersi mostly resembles S. denticulata and can be distinguished from this species by the combination of shorter mandibles (ML 0.288 and MI 65.6 from the former opposed to the ML 0.355 and MI 84.9 from the latter), humeral setae filiform ( Fig. 6B ), presence of a pair of erect setae in the anteromedial area of the pronotum ( Fig. 6B ), and fourth abdominal tergite mostly sculptured.

Type material

Lectotype (designated herein) (label information) ( Fig. 5 ) BRAZIL • “ Strumigenys eggersi St. Thomas Eggers ” [handwritten]; “Typus” [printed]; “ ANTWEB CASENT 0904936 ” [printed]; “ Strumigenys eggersi Emery, 1890 LECTOTYPE” [printed]; MCSN .

Paralectotypes (label information) BRAZIL • 2 workers; same label information as for lectotype; “ Strumigenys eggersi Emery, 1890 PARALECTOTYPE” [printed]; MCSN • 1 worker; same label information as for lectotype; “ Strumigenys eggersi Emery, 1890 PARALECTOTYPE ” [printed]; “ MZSP78535 ” [printed]; MZSP • 1 worker; “ St. Thomas ” [handwritten]; “ G. Mayr ” [printed]; “Type” [printed]; “ Strumigenys eggersi Emery, 1890 PARALECTOTYPE ” [printed]; “ NHMW-HYM4953 ” [printed]; NHMW • 1 worker; same label information as for preceding; “ NHMW-HYM4954 ” [printed]; NHMW • 1 worker; “ S. Thomas ” [handwritten]; “ Strumigenys eggersi Em. ” [handwritten]; “ Strumigenys Eggersi Emery S. Thomas ” [handwritten]; “Type” [printed]; “GBIF-D/FoCol 2160 specimen + label data documented” [printed]; ZMHB .

Additional material examined

BRAZIL – Bahia • 5 workers; Ilhéus ; 14°47′36.62″ S, 39°2′46.97″ W; [no date]; [no collector]; MZSP . – Espírito Santo • 1 worker; Reserva Biológica Córrego Grande ; 18°10′55.8″ S, 39°54′19.8″ W; 51 m a.s.l.; 31 Jan. 2018 – 5 Feb. 2018; N. Safar, H. Cândido, and M. Cóser leg.; Winkler; CELC, UFV- LABECOL-008214 . – Mato Grosso • 1 worker; Canarana-Querência ; 13°04′ S, 52°23′ W; M. Bicalho and V. Ribeiro leg.; UFV-LABECOL-001788 . – Minas Gerais • 1 worker; Viçosa ; 13 Mar. 1998; S.M. Soares leg.; CELC, UFV-LABECOL-001805 • 1 worker; Araponga ; Apr. 2011; D. Muscardi; CELC, UFV-LABECOL-001811 • 1 worker; Viçosa, Horto UFV ; 20°45′24.11″ S, 42°52′26.43″ W; 660 m a.s.l.; Mar. 2012; J. Chaul leg.; CELC, UFV-LABECOL-001790 • 1 queen; Viçosa ; 20°46′12.3″ S, 42°52′02.4″ W; 29 Feb. 2016; S. Epifânio, R. Jesus and J. Chaul leg.; CELC, UFV-LABECOL-007490 • 1 worker; Monte Carmelo ; 23–26 May 2016; J.M.M. Aguiar leg.; CELC, UFV-LABECOL-008354 • 1 queen; Buritizeiro, Fazenda Porto ; Feb. 2005; R.B.F. Campos leg.; CELC, UFV-LABECOL-001816 • 1 worker; Ipaba, Fazenda Macedônia ; Jan. 2005; T. Marques leg.; CELC, UFV-LABECOL-001813 . – Santa Catarina • 1 queen; Araranguá, Restinga Morro dos Conventos ; 7–23 Jan. 2008; D.C. Cardoso and M.P. Cristiano leg.; CELC, UFV-LABECOL-001815 . – Pará • 1 worker; Paragominas ; Jan.–Jul. 2011; R. Solar leg.; CELC, UFV-LABECOL-001778 . – Paraná • 1 worker; Matinhos ; 25°49′26.94″ S, 48°32′58.14″ W; [no date]; [no collector]; MZSP . – Rio Grande do Sul • 2 workers; Morro Reuter ; 29°32′18″ S, 51°4′53.86″ W; [no date]; [no collector]; MZSP . – Rio de Janeiro • 1 worker; Santa Teresa ; 22°56′42.11″ S, 43°12′39.70″ W; [no date]; [no collector]; MZSP . – São Paulo • 1 worker; Ilha dos Búzios ; 23°47′56.89″ S, 45°7’60.00″ W; [no date]; [no collector]; MZSP .

Lectotype measurements

ABD4L 0.321; DPW 0.104; EL 0.043; HL 0.439; HT 0.25; HW 0.366; ML 0.288; PH 0.115; PL 0.197; PPL 0.098; PW 0.245; SL 0.221; WL 0.461; TL 1.872; CI 83.4; DPI 52.8; LPI 58.4; MI 65.6; OI 11.7; SI 60.4.

Paralectotype measurements

ABD4L 0.304; DPW 0.102; EL 0.036; HL 0.415; HT 0.253; HW 0.343; ML 0.278; PH 0.107; PL 0.202; PPL 0.087; PW 0.241; SL 0.230; WL 0.443; TL 1.729; CI 82.7; DPI 50.5; LPI 53.0; MI 67.0; OI 10.5; SI 67.1 (n = 1; ZMHB GBIF-D/FoCol 2160).

Non-type measurements

ABD4L 0.320 –0.410; DPW 0.085 –0.115; EL 0.040 –0.050; HL 0.420 –0.470; HT 0.240 –0.270; HW 0.340 –0.390; ML 0.250 –0.280; PH 0.110 –0.130; PL 0.190 –0.210; PPL 0.080 –0.100; PW 0.220 – 0.255; SL 0.220 –0.250; WL 0.420 –0.490; TL 1.690 –1.955; CI 81.0–86.0; DPI 44.7–55.3; LPI 55.0– 61.9; MI 58.1–65.9; OI 10.8–14.1; SI 62.0–66.7 (n = 6).

Description

SCULPTURE. Head entirely reticulate-punctate, including antennal scrobe. Mesosoma entirely reticulatepunctate, except for katepisternum which is smooth ( Fig. 6B ). Fourth abdominal tergite reticulatepunctate almost entirely. Length of basigastral costulae, in dorsal view, less than half the length of postpetiole.

SETAE. Cephalic ground-setae remiform (Fig, 6A). Two pairs of remiform erect setae on cephalic dorsum; both pairs located in the posterior third of cephalic dorsum, one pair nearer to occipital margin than the other. Apicoscrobal setae flagellate ( Fig. 6A ). Anterior margin of scape with one or more remiform setae curved towards antennal insertion. Humeral setae filiform ( Fig. 6B ). Pair of erect setae located in the antero-medial area of pronotum filiform ( Fig. 6B ). Setae on petiole, postpetiole and fourth abdominal tergite remiform to slightly clavate.

HEAD. Masticatory margin of mandible with six preapical denticles ( Fig. 6A ). Apex of mandible with two minute intercalary denticles ( Fig. 6A ). Anterior clypeal margin, in dorsal view, convex medially. Eye, in lateral view, with three ommatidia in the longest row. Eye located in the anterior half of head. In dorsal view, scape cylindrical. Third flagellomere smaller than fourth flagellomere; length of former almost a third of length of latter.

MESOSOMA. Humerus with a small angular projection. Dorsum of mesonotum, in lateral view, convex, confluent with dorsum of pronotum. Metanotal groove relatively well impressed. Propodeal spine relatively long and triangular, somewhat translucent, and linked to propodeal lobe by a narrow lamella that extends throughout propodeal declivity. Femoral bulla small, ovate and located distally on the dorsal margin of sclerite.

METASOMA. Petiolar node, in dorsal view, wider than long; in lateral view, anterior margin longer than dorsal margin. Anterior margin of postpetiole, in dorsal view, medially concave. Lateral and ventral spongiform processes of petiole absent. Ventral spongiform lobe of postpetiole small ( Fig. 6B ). Lateral spongiform lobe of postpetiole minute, almost vestigial ( Fig. 6B ). Ventral basigastral spongiform pad reduced to curved (U-shaped in anterior view) carina.

Comments

Bolton (2000) considered S. eggersi as a member of the gundlachi complex (i.e., a cluster of species under the gundlachi species group), along with Strumigenys connectens Kempf, 1958 , S. decipula ( Bolton, 2000), S. denticulata Mayr, 1887 , S. enopla ( Bolton, 2000), S. gemella Kempf, 1975, S. gundlachi (Roger, 1862), S. jamaicensis Brown, 1959, S. laevipleura Kempf, 1858, S. lalassa ( Bolton, 2000), S. nubila Lattke & Goitía, 1997, S. subedentata Mayr, 1887 , S. trieces Brown, 1960, S. vartana ( Bolton, 2000), and S. xenognatha Kempf, 1958.

This species is widespread in the Neotropics, with its northernmost range in Florida, USA ( Wetterer 2018) and southernmost range in Santa Fé, Argentina ( Vittar & Cuezzo 2008). According to Wetterer (2018), this species can be commonly found in urban areas when occurring outside its original range, which was, according to Brown (1960), “probably south Brazil and Bolivia, though a lack of collections from central and northern Brazil prevents us from knowing how far north this species extends”. Since Brown’s (1960) work, the number of records of S. eggersi in the Neotropical region has greatly increased, especially due to recent sampling efforts conducted in ecosystems both within and adjacent to the Amazon basin. Nonetheless, there still remains a large record gap for the species in the center of the Amazon biome. Although the revision of the species was not the aim of the present work, it is important to consider that the continuous reduction of this ‘distribution gap’ is fundamental when addressing the specific boundaries for S. eggersi .

Among the specimens examined, dentition patterns varied greatly, both in size and number. In the lectotype, there are total of seven preapical teeth restricted to the distal third of the inner margin of the mandible, while in some other specimens observed there are five or six preapical teeth. Bolton (2000) mentioned that specimens belonging to S. eggersi can have four to eight teeth in the inner margin of the mandible, indicating that teeth variation is expected in this species. However, Longino (2006) provided an important account on the usefulness of teeth variation in demarcating different species of Strumigenys belonging to the gundlachi group, indicating that dental variation (number and relative size of teeth) should be carefully considered when discriminating potential new species in this group.

Figures

Fig. 5. Lectotype of Strumigenys eggersi Emery, 1890 (CC-BY, CASENT0904936, Will Ericson, from www.antweb.org). A. Head, mandibles and antennae, in dorsal view.B. Full body, in lateral view.C. Full body, in dorsal view.

Fig. 6. Generalized schematics of Strumigenys eggersi Emery, 1890, showing useful identification features. A. Head in dorsal view. B. Mesosoma, petiole, and postpetiole in lateral view.