Ochetellus Shattuck 1992
Creators: name: Yoshimura, Masashi
name: Fisher, Brian L.
Publisher: name: Zenodo
Year: 2011
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Insecta
Hymenoptera
Formicidae
Ochetellus

description: Ochetellus Shattuck, 1992
(Figs 1, 8, 12, 18, 20, 25, 31, 34, 43, 46, 51, 57, 63, 68, 73, 78)
With characters of Dolichoderinae. All known males alate. Median hypostoma present (Fig. 63). Mandible triangular, but its basal angle indistinct. Basal margin of mandible without denticles and smooth, and masticatory margin with several stout teeth and minute denticles (Fig. 73). Apical tooth on masticatory margin longer than subapical one. Palpal formula 6,4 (one specimen of O. glaber from Japan was dissected: Fig. 78). Third maxillary palpal segment longer than fourth, but shorter than combined length of fourth and fifth. Distal margin of labrum widely concave and bilobed, with longest setae located near apices of lobes (Fig. 68). Scape excluding its basal condyle shorter than length of flagellar segments 1+2 (Fig. 1). Pedicel barrel-shaped. Lateral margins of first flagellar segment slightly convex, and those of second segment straight. Axillae not medially compressed, anterior and posterior margins roughly parallel. Petiolar node raised vertically, its anterior margin as long as posterior margin in lateral view. Node strongly expanded laterally so that its posterior attachment conceals anterior portion of abdominal segment III in dorsal view. Petiole broadly attached to abdominal segment III (Fig. 18). Anterior surface of abdominal segment III without indentation (Fig. 20). Pygostyles present.
Distal portion of abdominal sternum IX bilobed, its distal margin widely concave (Fig. 25). Apicoventral portion of basimere without projection (Fig. 31). Harpago moderate in size, widely separated from basimere by membranous region, narrow in lateral view, without distinct ventral face (as in Fig. 23). Basal portion of aedeagus does not bear distinct ventral lobe (Fig. 43). Ventral margin of aedeagus with denticles.
Forewing not extremely elongate apical to wing stigma, its radial sector reaches costal margin (Fig. 51), media absent apical to 1m-cu, short branch of 2rs-m recognizable, and 1m-cu present. On hindwing, M+Cu and 1rs-m+M present, free sections of radial sector and cubitus vestigial, cu-a present (Fig. 57), clavus larger.
Remarks. Only males of Ochetellus glaber collected in Japan and Hawaii were available. Males of Ochetellus are distinguished easily from those of the four other Malagasy dolichoderine genera by a barrel-shaped pedicel (not narrowed basally), a laterally expanded petiole broadly attached to abdominal segment III (Fig. 18), and lack of an indentation on the anterior surface of abdominal segment III (Fig. 20). A laterally expanded petiole is found in one species of Tapinoma (Tapinoma mg11); however, its attachment with the third abdominal segment is narrow. The basal margin of the mandible is completely smooth; the only Malagasy dolichoderine genera that lack dentition on the basal margin are Ochetellus (Fig. 73) and Ravavy (Fig. 74). The posterior margin of mesoscutum is notched, but this character is also found in a species of Tapinoma (Tapinoma mg10).
Several of the present results for Ochetellus glaber disagree with those in previous studies. In this study, a median notch was observed on the posterior margin of the medial hypostoma (Fig. 63), while Ochetellus has been assigned by Shattuck (1992a) to a group having the hypostomal margin entire. The third maxillary palpal segment is longer than the fourth but shorter than the fourth plus fifth, while in Shattuck (1992a), Ochetellus has been assigned to a group with the third segment equal in length to the fourth. Abdominal segment III rises vertically in Ochetellus glaber, although this character has been regarded as elongate posteriorly in Shattuck (1995) and Brandão et al. (1999). The distal margin of the ninth abdominal sternum is concave (Fig. 25), while the margin in Shattuck (1992a, 1995) and Brandão et al. (1999) is regarded as entire and flat. The cuspis on the volsella is present (Fig. 46), but is recorded as absent in Shattuck (1992a, 1995) and Brandão et al. (1999).
Shattuck (1992a, 1995) and Brandão et al. (1999) proposed many male diagnostic characters to distinguish and analyze the relationships among dolichoderine genera. A number of the characters they provide are useful and have been included in the present study. However, some are more useful for recognizing species than genera. The anteromedial margin of the clypeus, inner margin of the compound eye, relative length of the third maxillary palpal segment compared with the fourth, relative length of the first flagellar segment compared with its width, the degree to which the petiole is concealed by abdominal segment III in dorsal view, and the presence of the cuspis varied considerably even within a single genus. The variation seen for the above characters is shown in Table 4.
1. Anteromedial margin of the clypeus is never notched or concave (0); broadly and shallowly concave (1); distinctly notched medially (2)
2. Inner margin of the eye in full-face view convex (2); concave (1); flat (0)
3. The third maxillary palpal segment is shorter than the fourth (0); equal with the fourth (1); longer than the fourth (2)
4. The first flagellar segment is three or more times as long as broad (2); less than three times but more than twice as long as broad (1); twice or less long as broad (0)
5. Indentation of abdominal segment III completely conceals the petiole in dorsal view (1); conceals only base of the petiole (0)
6. Cuspis of the volsella is absent (1); present (0)
Some character states proposed in Shattuck (1992a, 1995) and Brandão et al. (1999) were identical among all Malagasy genera examined in the present study and as a result are omitted from the character matrix (Tables 3, 4). In all of the material examined, the following character states were shared across genera: (1) the posterior margin of the clypeus is located anterior to the line drawn through posterior-most points of the antennal condyles; (2) the anterior clypeal setae are short and do not reach the anterior margin of the mandible; (3) the axillae fuse into a single horizontal plate in most cases without any longitudinal suture dividing them; (4) the pygostyle is present; (5) the digitus of the volsella has a down-curved tip; (6) the ventral margin of the aedeagal plate is dentate; (7) the pterostigma is developed without a “pterostigmal appendage” (Wheeler 1934: fig. 2); and (8) the radial sector in the forewing reaches the costal margin. In addition, we omitted a character for the location of posterior clypeal margin relative to the antennal condyle because no dolichoderine genus in the Malagasy region was distinguished by this character. The value of these characters to separate Malagasy genera from those in other regions was not assessed.
Some diagnostic characters proposed by Shattuck (1992a, 1995) were omitted from the character matrix because they proved difficult to score. The omitted characters include: concavity of the declivity of the propodeum, presence of a petiolar scale, angle of petiolar dorsum, development of the subpetiolar process, and size of the harpago. For example, the dorsal and declivitous margins of the propodeum are often completely continuous and without any divisions and landmarks between them, although only Ravavy miafina has a much longer dorsal margin. In addition, the “ventral lobe of the volsella” (sensu Shattuck 1992a) was not included because it could not be recognized.
In most males examined, we observed a process in the buccal cavity near the base of the mandible that projected inward. However, it was difficult to judge whether this process is the “anterior hypostomal flange” proposed by Shattuck (1992a, 1995). One species that clearly lacks this process is Ravavy miafina, while others seemed to have at least a weak process. Ward et al. (2010) included the lack of the process as part of their diagnosis of the tribe Leptomyrmecini. However, Ravavy also lacks this process and is a member of the tribe Bothriomyrmecini. In contrast, Ochetellus, which has this process, is a member of the Leptomyrmecini. Therefore, the hypostomal process is not always a useful character to diagnose the Leptomyrmecini.
description: Published as part of Yoshimura, Masashi & Fisher, Brian L., 2011, A revision of male ants of the Malagasy region (Hymenoptera: Formicidae): Key to genera of the subfamily Dolichoderinae, pp. 1-34 in Zootaxa 2794 on pages 10-11, DOI: 10.5281/zenodo.276993