Leptanilloides Mann, 1823

Delsinne, Thibaut, Sonet, Gontran & Donoso, David A., 2015, Two new species of Leptanilloides Mann, 1823 (Formicidae: Dorylinae) from the Andes of southern Ecuador, European Journal of Taxonomy 143, pp. 1-35 : 5-8

Genus Leptanilloides Mann, 1823

Diagnosis of the Leptanilloides biconstricta species-group

Species from the Leptanilloides biconstricta species-group possess the typical characters of the genus (see diagnosis in Borowiec & Longino 2011) but can be grouped by the fact that they share the following criteria: promesonotal connection completely unfused and flexible; lateroclypeal tooth (called genal tooth in Brandão et al. 1999, Longino 2003 and Donoso et al. 2006) well-developed (although apparently lacking in L. caracola Donoso et al., 2006 , a species known only by its holotype; because this criterion may be difficult to observe with a stereo microscope, even at high magnification, the absence of a lateroclypeal tooth in L. caracola should be confirmed in SEM); abdominal segment III (postpetiole) nearly as high as abdominal segment IV; and postpetiolar spiracle situated proximately to the anterior margin of the tergite.

Moreover, species from this group are generally smaller than species of the L. legionaria species-group ( Fig. 1 ).

This group includes the ten following species:

L. atlantica Silva et al., 2013

L. biconstricta Mann, 1923

L. caracola Donoso et al., 2006

L. copalinga Delsinne & Donoso sp. nov.

L. erinys Borowiec & Longino, 2011

L. femoralis Borowiec & Longino, 2011

L. gracilis Borowiec & Longino, 2011

L. improvisa Brandão et al., 1999

L. prometea Delsinne & Donoso sp. nov.

L. sculpturata Brandão et al., 1999

Diagnosis of the Leptanilloides legionaria species-group

Species from the Leptanilloides legionaria species-group possess the characters of the genus (see diagnosis in Borowiec & Longino 2011) but are grouped because they share the following criteria: promesonotal connection at least partially fused; lateroclypeal tooth absent or reduced; postpetiole reduced and isolated; and postpetiolar spiracle shifted posteriad on anteromedian side of the tergite.

This group includes the following four species:

L. legionaria Brandão et al., 1999

L. mckennae Longino, 2003

L. nomada Donoso et al., 2006

L. nubecula Donoso et al., 2006

Key to workers of Leptanilloides

1. Abdominal segment III (postpetiole) in lateral view much smaller than adjoining fourth abdominal segment. Spiracle of segment III shifted posteriad on anteromedian side of tergite. Body size relatively large, HL 0.68–0.75 ( Fig. 1 ) ………………2 ( L. legionaria species-group)

– Abdominal segment III (postpetiole) in lateral view nearly as high as abdominal segment IV. Spiracle of segment III situated forward on the tergite. Body size relatively small, HL 0.31–0.62 ( Fig. 1 ) ……………………………………………………………5 ( L. biconstricta species-group)

2. Head subquadrate, CI 85–88; lateral margin nearly straight and parallel. Propodeal declivity short and vertical, propodeum with dorsal and posterior faces clearly differentiated ( Ecuador) ……… ……………………………………………………………………… L. nomada Donoso et al., 2006

– Head subrectangular, CI 75–83; lateral margin convex. Propodeal declivity usually rounded without clear distinction between dorsal and posterior faces ……………………………………3

3. Head sculpture less dense, at most 10–12 shallow foveolae across face at midlength. Lateral margin of head distinctly convex. Lateroclypeal tooth present. Posterior margin of head slightly concave ( Colombia) …………………………………………………… L. legionaria Brandão et al., 1999

– Head sculpture denser, with at least 15 foveolae across face at midlength. Lateral margin of head slightly convex. Lateroclypeal tooth absent. Posterior margin of head deeply concave …………4

4. Legs shorter, HW/HTL×100> 78. Hypostomal tooth present ( Ecuador) ………………………… ………………………………………………………………… L. nubecula Donoso et al., 2006

– Legs longer, HW/HTL×100 <78. Hypostomal tooth absent ( Costa Rica) ……………………… ………………………………………………………………………… L. mckennae Longino, 2003

5. Lateroclypeal tooth absent. Masticatory margin of mandible edentate ( Ecuador) ………………… …………………………………………………………………… L. caracola Donoso et al., 2006

– Lateroclypeal tooth present. Masticatory margin of mandible dentate (at least minute denticles present) ……………………………………………………………………………………………6

6. In lateral view, abdominal segment IV narrowly attached to preceding segment III and broadly to succeeding segment V, with contrast between widths of anterior and posterior articulations of segment IV in lateral view …………………………………………………………………7

– In lateral view, abdominal segment IV relatively broadly attached to preceding segment III, with little contrast between widths of anterior and posterior articulations of segment IV in lateral view ………………………………………………………………………………………8

7. In lateral view, sternite of abdominal segment III evenly rounded, making sternal and tergal portions subequal. Petiole as long as postpetiole. Reticulation on mesopleuron and metapleuron uninterrupted. Head densely foveolate, with c. 20–30 foveolae covering a straight transverse line at head midlength. HL ≤ 0.36 ( Brazil) ……………………………… L. atlantica Silva et al., 2013

– In lateral view, sternite of abdominal segment III (postpetiole) distinctly bulging anteriorly, making sternal portion of segment deeper than tergite ( Borowiec & Longino 2011: fig. 2d). Petiole longer than postpetiole ( Borowiec & Longino 2011: fig. 2d). Reticulation on mesopleuron and metapleuron superficial and interrupted. Head sculpture less dense, with only 10–20 foveolae covering a straight transverse line at head midlength. HL = 0.49 in only measured specimen ( Bolivia, Colombia, Venezuela) ………………………………………… L. biconstricta Mann, 1823

8. In lateral view, petiolar sternite distinctly bulging medially ……………………………………9

– In lateral view, petiolar sternite straight (not bulging) or bulging anteriorly …………………10

9. Hindtibia with two very small, simple spurs, without pectinate spur clearly visible under 50× magnification. Petiolar spiracle opening in an excavation distinctly larger than propodeal spiracle ( Borowiec & Longino 2011: fig. 5g–h). Flange over metapleural gland opening sharply pointed posteriorly ( Mexico, Guatemala) ………………………… L. gracilis Borowiec & Longino, 2011

– Hindtibia with large pectinate spur, clearly discernable under 50× magnification. Petiolar spiracle not in excavation, similar and subequal to or smaller in diameter than propodeal spiracle ( Borowiec & Longino 2011: fig. 4g–h). Flange over metapleural gland opening rounded posteriorly ( Venezuela) ……………………………………………… L. femoralis Borowiec & Longino, 2011

10. Head narrow, HL <0.30, HW <0.20, CI <60. Head dorsum densely foveolate with foveolae separated by less than their diameter, often contiguous ( Colombia) ……………………………… ………………………………………………………………… L. sculpturata Brandão et al., 1999

– Head broader, HL> 0.30, HW> 0.20, CI> 65. Head dorsum less densely foveolate, with foveolae separated by about their diameter or more ……………………………………………11

11. Size large, HL ≥ 0.50, HW ≥ 0.38. Flange over metapleural gland opening short, not surpassing propodeum declivity margin in lateral view, and rounded posteriorly ………………………12

– Smaller, HL <0.45, HW <0.35. Flange over metapleural gland opening long, surpassing propodeum declivity margin in lateral view, and sharply pointed posteriorly ………………13

12. HL = 0.50 on single known specimen. Masticatory margin of mandible distinctly dentate, with regularly spaced and well-developed teeth ( Brandão et al. 1999: fig. 16) ( Ecuador) …………… …………………………………………………………………… L. improvisa Brandão et al., 1999

– HL ≥ 0.58. Masticatory margin of mandible dentate but teeth extremely minute, blunt and irregularly shaped, difficult to discern even under magnifications of about 100× ( Figs 4B , 6C ) ( Ecuador) ……………………………………………… L. prometea Delsinne & Donoso sp. nov.

13. Ventral margin of petiolar sternite forming an even convexity in lateral view. Reticulation on mesopleuron, metapleuron and lateral side of petiole uninterrupted. In dorsal view, petiole subquadrate, 67 ≤ PI ≤ 80 ( Ecuador) ……………………… L. erinys Borowiec & Longino, 2011

– Ventral margin of petiolar sternite relatively straight in lateral view ( Fig. 3C ). Reticulation on mesopleuron, metapleuron and lateral side of petiole superficial and interrupted. In dorsal view, petiole slender, rectangular, 52 ≤ PI ≤ 63 ( Fig. 3D ) ( Ecuador) …………………………………… ………………………………………………………… L. copalinga Delsinne & Donoso sp. nov.

Figures

Fig. 1. Relationship between HL and WL among workers in species of Leptanilloides and Asphinctanilloides. Specimens measured are holotypes or paratypes. Measurements are in mm. WL is called Mesosoma Length (ML) in Borowiec & Longino (2011) and Silva et al. (2013). Triangles: the two Leptanilloides described in this paper (L. copalinga Delsinne & Donoso sp. nov. and L. prometea Delsinne & Donoso sp. nov.); diamonds: Leptanilloides biconstricta species-group (La: L. atlantica, Lb: L. biconstricta, Lc: L. caracola, Le: L. erinys, Lf: L. femoralis, Lg: L. gracilis, Li: L. improvisa, Ls: L. sculpturata); dots: Leptanilloides legionaria species-group (Ll: L. legionaria, Lm: L. mckennae, Lno: L. nomada, Lnu: L. nubecula); stars: Asphinctanilloides species (Aa: A. amazon Brandão et al., 1999, Aan: A. anae Brandão et al., 1999, Am: A. manauara Brandão et al., 1999).

Fig. 4. Leptanilloides prometea Delsinne & Donoso sp. nov. – A–C. Paratype worker (specimen code 4052301). A. Habitus, dorsal view. B. Head in full-face view. C. Habitus, lateral view. – D. Apex of hindtibia; reservoir of metatibial gland is visible under translucent cuticle at the base of the tibial spur (paratype, specimen code 4052313).

Fig. 6. Leptanilloides prometea Delsinne & Donoso sp. nov. Paratype worker (specimen code 4052301). A. Head, ventral view. B. Mesotibial pectinate spur. C. Anterior part of the head in full-face view, showing vertical and fused frontal carinae, exposed antennal socket, well-developed lateroclypeal tooth, strongly convex clypeal lamella and subtriangular mandible with minute denticles along its inner margin. D. Lower part of propodeum in lateral view, showing the flange over the metapleural gland opening. E. Petiole in lateral view. F. Simple claw (hindleg).

Fig. 3. Leptanilloides copalinga Delsinne & Donoso sp. nov. Paratype worker (specimen code 4006301). A. Anterior part of the head in full-face view, showing vertical and fused frontal carinae, exposed antennal socket, lateroclypeal tooth, strongly convex clypeal lamella and subtriangular mandible with minute denticles along its inner margin. B. Lower part of propodeum in lateral view, showing the long and sharp flange over the metapleural gland opening. C. Petiole in lateral view. D. Propodeum and petiole in dorsal view. E. Abdominal segment III (postpetiole) in lateral view. F. Mesotibial spur, short and pectinate.