Research Article |
Corresponding author: Himender Bharti ( himenderbharti@gmail.com ) Academic editor: Marek Borowiec
© 2021 Himender Bharti, Joginder Singh Rilta, Tarun Dhadwal.
This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Citation:
Bharti H, Rilta JS, Dhadwal T (2021) Two new species of Ooceraea (Hymenoptera, Formicidae, Dorylinae) from India with ten-segmented antennae. ZooKeys 1010: 165-183. https://doi.org/10.3897/zookeys.1010.58436
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Two new species, O. decamera sp. nov. and O. joshii sp. nov., of the ant genus Ooceraea are described from India. These species differ from other known congeners on the basis of number of antennal segments. An illustrated key to the known species based on the worker caste is also provided.
Cerapachys, distribution, illustrated key, O. decamera sp. nov., O. joshii sp. nov., systematics, taxonomy
The taxonomic history of the ant genus Ooceraea Roger, 1862 has been challenging, since its inception based on the type species O. fragosa. The taxonomic ambiguity has led to its uncertain placements in different subfamilies: in Myrmicinae (
The genus is currently represented by 14 species (
Taxonomic analysis was conducted on a Nikon SMZ 1500 stereo zoom microscope with maximum magnification of 112.5×. Digital images of the specimens were prepared using a Nikon SMZ 1500 stereomicroscope fitted with a Micro Publisher digital camera (Figs
HL Head length: maximum length of head capsule in full-face view, measured from transverse line spanning the anterior most point of clypeus to that of posterior most point of head capsule;
HW Head width: maximum width of head capsule in full-face view (excluding eyes);
SL Scape length: maximum length of antennal scape excluding basal condylar bulb;
MW Mesosomal width: maximum width of promesonotum in dorsal view;
ML Mesosomal length: maximum diagonal length of mesosoma in lateral view, measured from posterodorsal border of pronotal flange to posterior basal angle of metapleuron;
PL Petiolar length: maximum length of petiole in lateral view;
PH Petiolar height: maximum height of petiole in lateral view (including subpetiolar process);
PW Petiolar width: maximum width of petiole in dorsal view;
PPL Postpetiolar length: maximum length of postpetiole in lateral view;
PPH Postpetiolar height: maximum height of postpetiole in lateral view;
PPW Postpetiolar width: maximum width of postpetiole in dorsal view;
CI Cephalic index: HW/HL × 100;
SI Scape index: SL/HW × 100;
PI1 Petiolar index 1: PL/PH × 100;
PI2 Petiolar index 2: PW/PL × 100;
PPI1 Postpetiolar index 1: PPL/PPH × 100;
PPI2 Postpetiolar index 2: PPW/PPL × 100;
WI Waist index: PPW/PW × 100.
Depositories
India, Kerala, Periyar Tiger Reserve 9.5627°N, 77.2348°E, 780 m.
Holotype: HL 0.57; HW 0.56; SL 0.34; MW 0.39; ML 0.68; PL 0.29; PH 0.34; PW 0.27; PPL 0.32; PPH 0.34; PPW 0.30; CI 98; SI, 61; PI1 85; PI2 93; PPI1 94; PPI2 88; WI 111. Paratype: HL 0.57; HW 0.56; SL 0.33; MW 0.39; ML 0.68; PL 0.29; PH 0.33; PW 0.26; PPL 0.32; PPH 0.34; PPW 0.30; CI 98; SI, 59; PI1 88; PI2 89; PPI1 94; PPI2 88; WI 111.
Head in full-face view, almost as long as broad, with lateral margin weakly convex and converging anteriorly, with posterior margin concave medially and posterior lateral corners rounded. Anterior clypeal margin reduced and slightly concave in the middle. Eyes present, small in size, with two ommatidia, parafrontal ridge prominently produced. Mandibles edentate, sub-triangular. Antenna 10-segmented; scape short and clavate, reaching almost mid-length of the head; apical funicular segment fusiform. Frontal lobes reduced. Antennal sockets fully exposed from above.
Mesosoma in lateral view weakly convex; promesonotal suture and metanotal groove absent. Pronotum in dorsal view anteriorly marginate. Propodeum in dorsal view with posterior margin concave; propodeal declivity in lateral view slightly concave, with lateral margin slightly marginate; propodeal lobe reduced. Petiolar node in dorsal view as long as broad, rounded anteriorly, in lateral view hemiglobular; subpetiolar process well-developed, with sickle-shaped anteroventral apex. Postpetiole in dorsal view subtrapezoidal, with anterior margin transverse and posterior margin convex, in lateral view with anteroventral corner angulate. Gastral segment I (abdominal segment IV) large, occupying the most part of gaster, in lateral view with dorsal margin weakly and roundly convex.
Sculpture. Head foveolate-reticulate; mesosoma, petiole and postpetiole foveolate-reticulate; gaster foveolate, with foveae smaller than those of head and mesosoma.
Pilosity and Pubescence. Body covered with erect or sub-erect hairs; sides of head and legs covered with shorter hairs; scape and funicular segments covered with short decumbent or subdecumbent hairs.
Body coloration. Head and gaster light brown; mesosoma, petiole and postpetiole darker than the head; legs yellowish brown.
Queen. Unknown.
Male. Unknown.
Ooceraea joshii sp. nov. and O. decamera sp. nov. (described below) are distinctly separated from the other valid congeners by having 10-segmented antennae. Furthermore, the two new species are well distinguished from each other by a combination of the following characters: head shape (almost as long as broad in O. joshii sp. nov., rectangular, distinctly longer than broad in O. decamera sp. nov.); presence of ommatidia (present in O. joshii sp. nov. and absent in O. decamera sp. nov.); propodeal lobes (reduced versus roundly produced); petiolar node in lateral view (hemiglobular versus rectangular); subpetiolar process (anteroventral part sickle-shaped versus forming a rectangular and semitransparent lobe); pilosity (head and body comparatively more pilose in O. joshii sp. nov.); and sculpturation (head, mesosoma, petiolar, postpetiolar node, and gaster with more pronounced foveolate sculpture in O. joshii sp. nov.).
The type series was found in leaf litter samples collected from the Medaganam region of the Periyar Tiger Reserve situated at an elevation of 780 meters. The region is composed of an undisturbed tropical moist evergreen forest with low light penetration, with a mean average daytime temperature of 30 °C.
Known only from the type locality.
The species has been named in honor of Professor Amitabh Joshi, a distinguished evolutionary biologist based at Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR), Bengaluru, India.
India: Madras, Alagarkovil, 21 km. N Madurai, 10.02308°N, 77.833333°E, 250–350 m alt.
Holotype
worker, India, Madras, Alagarkovil, 21 km N Madurai, 10.02308°N, 77.833333°E, 250–350 m alt.; 2 November 1972; Besuchet Lobt Mussard leg. (Specimen number/barcode: MCZ-ENT00649398) [
Head in full-face view rectangular, distinctly longer than broad (CI 74), with lateral sides weakly convex, with posterior margin concave medially, with occipital lobes/corners angulate. Anterior clypeal margin slightly projecting forward. Eyes absent. Parafrontal ridge prominent and elevated. Mandibles edentate but weakly serrate. Antennae with 10 segments; scape short, clavate, slightly surpassing the mid-length of head. Frontal lobes reduced. Antennal sockets fully exposed from above.
Mesosoma in lateral view almost flat; promesonotal suture and metanotal groove absent. Pronotum in dorsal view with anterior margin weakly and roundly convex, with humeral corner rounded. Propodeum in dorsal view with posterior margin concave; propodeal declivity in lateral view almost straight, with lateral margin marginate; propodeal lobe roundly produced. Petiolar node in dorsal view subtrapezoidal, distinctly broader than long, in lateral view rectangular with anterior and posterior margins almost straight and dorsal margin weakly convex. Subpetiolar process well-developed, with anteroventral part forming a rectangular and semitransparent lobe. Postpetiole broader than long, anterior margin weakly concave and posterior margin weakly convex, in lateral view with anteroventral part broadly and roundly produced. Gastral segment I (abdominal segment IV) large occupying the most part of gaster, in lateral view with dorsal margin almost straight, base of cinctus of first gastral tergite cross-ribbed.
Sculpture. Head, mesosoma, petiole and postpetiole shallowly foveolate-reticulate; mandibles and dorsal surface of gaster sparsely foveolate, foveae somewhat smaller as compared to those present on head, mesosoma, petiole, and postpetiole.
Pilosity and pubescence. Whole body covered with pale yellow erect and sub-erect hairs; appressed pubescence abundant on antennae and legs.
Body coloration. Mandibles, antennae, legs, subpetiolar process and gaster light brown; head, mesosoma and gaster dark brown.
Queen. Unknown.
Male. Unknown.
The two species significantly differ from each other on the basis of dimensions of head capsule and shape of subpetiolar process.
Unknown.
Known only from the type locality. The place has been transformed into agricultural land and is prone to anthropogenic activities. Thus, this reinforces the concept that important biodiversity components, which are already rare, are imperiled due to local extinctions.
Antennal count and distribution of Ooceraea species in different biogeographical regions.
Sr. No. | Species | Antennal count | Biogeographical region |
---|---|---|---|
1. |
Ooceraea octoantenna |
8 | Palearctic |
2. | Ooceraea alii (Bharti & Akbar, 2013) | 9 | Oriental |
3. | Ooceraea australis (Forel, 1900) | 9 | Australasia |
4. | Ooceraea biroi (Forel, 1907) | 9 | Malagasy, Neotropical, Oceania, Oriental, Palearctic |
5. | Ooceraea crypta (Mann, 1921) | 9 | Oceania |
6. | Ooceraea fuscior (Mann, 1921) | 9 | Oceania |
7. | Ooceraea papuana Emery, 1897 | 9 | Australasia |
8. | Ooceraea pawa (Mann, 1919) | 9 | Australasia |
9. | Ooceraea pusilla Emery, 1897 | 9 | Australasia |
10. |
Ooceraea quadridentata |
11 | Oriental |
11. | Ooceraea besucheti (Brown, 1975) | 11 | Oriental |
12. | Ooceraea coeca Mayr, 1897 | 11 | Oriental |
13. | Ooceraea fragosa Roger, 1862 | 11 | Oriental |
14. | Ooceraea guizhouensis (Zhou, 2006) | 11 | Palearctic |
We sincerely thank Dr Marek Borowiec for significant input on Ooceraea decamera sp. nov., Dr David Lubbertazi for providing access to the type material, Dr Eli Sarnat for providing images of Ooceraea crypta and Ooceraea fuscior, Dr Katsuyuki Eguchi for valuable comments on the manuscript and Mr Patrick McCormack for photography. We acknowledge the use of images from Antweb (CASENT0249322_D, CASENT0055090_D, ANTWEB1041156_P, D, CASENT0903779_D, CASENT0171152_P, D, H, CASENT0911143_D, CASENT0922424_D, CASENT0106215_D), from Museum of Comparative Zoology, Harvard University (MCZ-ENT00649398_H,P,D) Antwiki (Ooceraea pusilla Emery, 1897) and map from antmaps.org. Financial assistance rendered by the Ministry of Environment, Forest and Climate Change (Grant No. 22018/41/2010-CS (Tax)), Govt. of India, New Delhi is gratefully acknowledged. We also thank Forest and Wildlife Department, Govt. of Kerala for granting the permission to collect the research material vide Order No. WL 10-55389/2014 dated 07.01.2016.