Pyramica mariae Sosa-Calvo, Schultz

Jeffrey Sosa-Calvo, Ted R. Schultz & John S. Lapolla, 2010, A Review of the Dacetine Ants of Guyana (Formicidae: Myrmicinae), Journal of Hymenoptera Research 19, No. 1, pp. 11-43 : 18-21

Pyramica mariae Sosa-Calvo, Schultz , and LaPolla, n. sp.

( Figs 6, 8 , and 10)

Material examined.— Holotype: worker, labeled ‘‘ GUYANA: Mt. Ayanganna montane forest ; 1300 m; 59 ° 57.969 ' W 5 ° 22.483 ' N; 13.x.2002; T.R. Schultz, J. LaPolla, C. Marshall, R. Williams; litter sample.’’ USNM ENT No. 00413858 . (UGBC). Paratypes: 3 workers, same locality as in holotype. USNM ENT No. 00413859, 00442882, 00442883 . (USNM) .

Diagnosis (worker). — Mandibles linear, elongate, and narrow; inner margin of mandibles with two clearly defined teeth, which are larger than the rest; labral lobes short with long trigger hairs at their apices; metapleuron smooth and shining; ventral portions of petiole and postpetiole lacking spongiform tissue.

Description (worker). — Possessing characters of the gundlachi -group and gundlachi - complex ( Bolton 2000). Head: in full-face view nearly as broad as long; inner margin of elongate mandibles slightly concave to more or less straight, with 4 teeth on left mandible and 3 on right mandible, of which a pair of teeth are larger on each mandible (same in paratypes); with 2 minute intercalary denticles between apicodorsal and apicoventral fork teeth; labral lobes short, almost invisible in full-face view; trigger hairs long; eyes with 3 ommatidia in longest row, with 6–7 ommatidia in total. Cephalic dorsum with two pairs of erect hairs: one pair located close to occipital margin and another pair located close to highest point of vertex; each upper scrobal margin with a short apicoscrobal hair that projects laterally. Mesosoma: pronotum with a pair of short humeral hairs that project laterally; mesonotum with a pair of short, erect, stiff hairs; mesopleuron and metapleuron mostly smooth and shining; dorsum of promesonotum, propodeum, and propodeal declivity strongly reticulate. Metasoma: peduncle of petiole long, length of petiole 3–3.5 times longer than its disc; petiolar disc reticulate-punctate, with a pair of erect hairs on posterior portion of disc; ventral portion of petiole lacking spongiform tissue; disc of postpetiole reticulate, ventral portion of postpetiole lacking spongiform tissue; posterior portion of postpetiole disc with a row of 4 erect hairs; first gastral tergite almost entirely reticulate except for a small portion at posterior portion of tergite. Individuals light brown to brown.

Measurements: holotype (and paratype): GL = 0.59 (0.48), HL = 0.52 (0.48–0.50), HW = 0.42 (0.38–0.46), ML = 0.36 (0.36– 0.38), PL = 0.28 (0.24–0.27), PPL = 0.12, PW = 0.27 (0.23–0.24), SL = 0.30 (0.30– 0.31), TL = 2.47 (2.24–2.28), WL = 0.58 (0.55–0.56). Indexes: CI = 81 (78–92), MI = 73 (72–75), PI = 48 (43–49), SI = 71 (65–82). (n = 4)

Gyne and male.— Unknown

Etymology.— Named in honor of the first author’s mother, Maria del Carmen Calvo, in gratitude for her encouragement and support.

Comments.— Pyramica mariae n. sp. is clearly a member of the gundlachi -group (refer to Bolton [2000: 176– 179 p.] for further information). Within the gundlachi - group, Bolton (2000) identified two complexes, crassicornis and gundlachi. Pyramica mariae belongs to the gundlachi complex and resembles P. denticulata (Mayr) , P. enopla Bolton, and P. vartana Bolton. Pyramica mariae shares with P. vartana the smooth and shining mesopleuron and metapleuron, but P. mariae can be distinguished from P. vartana by the form of the apicoscrobal and pronotal humeral hairs, both short and stiff ( mariae ) rather than long and filiform ( vartana ), and the disc of the postpetiole is reticulate ( mariae ) rather than smooth and shining ( vartana ).

Pyramica mariae is of similar size and color as P. enopla . However, P. mariae differs from P. enopla in that the apicoscrobal, humeral, and mesonotal hairs are short, erect, and stiff ( mariae ) rather than long and filiform ( enopla ); the metapleuron is smooth and shining ( mariae ) rather than reticulate ( enopla ); the dorsum of the petiole bears a single pair of hairs ( mariae ) rather than two pairs of hairs ( enopla ); and the dorsum of the postpetiole lacks an anterior pair of hairs ( mariae ), present in enopla .

Pyramica mariae can easily be confused with P. denticulata ( Figs 7, 9 , and 11) with which it shares the most character states. However, the species can be separated by: (i) mandibular dentition: P. denticulata has 5–10 preapical denticles of similar size, whereas P. mariae has 3–4 preapical denticles, two of which are larger than the rest. In Pyramica mariae , at least in the four specimens examined, there are 4 teeth on the left mandible and 3 teeth on the right mandible; (ii) mesosomal sculpture: the metapleuron in P. denticulata is reticulate, whereas in P. mariae it is smooth and shining; (iii) petiole proportions: the petiolar peduncle in P. denticulata is relatively shorter ( PI 38–42) than in P. mariae ( PI 43– 49) ( Figs 12 –13).

The four specimens known of P. mariae were collected in a leaf-litter sample extracted with a mini-Winkler. The sample was collected in a primary lower montane forest (1300 m). Other species in the gundlachi -group have been recorded from wet forest habitats and from lowland rainforest to cloud forest and some in agroecosystems. Pyramica denticulata , the species perhaps most closely related to P. mariae , has been collected in lowland (<1000 m) forests in Panama ( Sosa-Calvo et al. 2006) to subtropical forests in the wet Chaco region of Argentina ( Theunis et al. 2005). Nothing is known about the biology of P. mariae other than the collection data.

MODIFIED VERSION OF KEY IN BOLTON (2000)

In Bolton’s (2000) key, Pyramica mariae keys out to P. denticulata . The key can be modified as below to include P. mariae . Numbering of couplets follows Bolton (2000).

23. In lateral view, postpetiole lacking ventral spongiform lobe; sometimes a minute vestige visible; mesonotum with a pair of erect hairs.................... 23b

– In lateral view, postpetiole with reduced ventral spongiform lobe but distinct; if lobe very shallow then mesonotum with pair of straggly (i.e., laid out in an irregular, untidy way) flagellate hairs....................... couplet 25 in Bolton (2000)

23b. Mandibles long, MI 72–85. Dorsum of pronotum lacking pair of stiff erect hairs... 23c

– Mandibles short, MI 58–65. Dorsum of pronotum with pair of stiff erect hairs... eggersi

23c. Inner margin of mandibles with 5–10 preapical denticles of similar size. Metapleuron densely reticulate. Peduncle of petiole short, PI 38–42.............. denticulata

– Inner margin of mandibles with 3–4 preapical denticles, two distinctly larger than rest. Metapleuron smooth and shining. Peduncle of petiole elongate, PI 48–49...................................................... mariae new species

Fig. 13. Relationship between petiole length and Weber’s length among Pyramica denticulata , P. mariae , and P. enopla . Measurements in millimeters.

Figures

Figs 6–11. Full-face (dorsal) and lateral views of the holotype worker of Pyramica mariae, new species (6, 8, 10) and P. denticulata (7, 9, 11).

Fig. 12. Relationship between head width and head length among Pyramica denticulata, P. mariae, and P. enopla. Measurements in millimeters.