Introduction

Apidae, the largest bee family of the world, includes over 6,090 species (Ascher & Pickering 2023). The size of the family justifies the placement of its taxa into 33 tribes which is the highest compared to other bee families. This family includes honeybees, carpenter bees, bumblebees, stingless bees, orchid bees, cuckoo bees and a few other lesser-known species. The bees of this family are prolific pollinators, contributing significantly to both the economy and the environment. Genus Tetralonioidella Strand, 1914, belongs to tribe Melectini, subfamily Apinae and family Apidae under superfamily Apoidea. Tribe Melectini consists of apiform to anthophoriform cleptoparasitic bees. These melectines are known to be parasites of Anthophorini species (Michener 2007). This genus has been recorded as cleptoparasitic on Habropoda Smith, 1854 and Elaphropoda Lieftinck, 1966 throughout Thailand, Malaysia, Sumatra, Java and Taiwan (Lieftinck 1972, Wu 2000). The presence of a variety of cleptoparasitic bees is a sign of a thriving bee community. These bees act as an indicator group and play a stabilizing role in preserving bee alpha diversity. They are quick to respond to environmental changes, making them valuable for inclusion in bee monitoring programs (Sheffield et al. 2013). Strand (1914) erected the genus Tetralonioidella based on the Taiwanese species Tetralonia hoozana Strand, 1914 (=Tetralonioidella hoozana (Strand, 1914)) and published one month before the description of genus Protomelissa Friese, 1914 (Lieftinck 1972). The designation and description of T. hoozana as type species (being the first inclusion in the genus) was rediscovered by Lieftinck (1983). This rediscovery held nomenclatural precedence over Protomelissa.

Tetralonioidella is a rare, oriental bee genus with a total of 19 species worldwide, among which only two have been reported from India (Ascher & Pickering 2023). The range of species distribution of Tetralonioidella extends from northern India and Nepal along the Himalayas through southeast China and Taiwan, as well as Thailand and Malaysia to far south as Sumatra and Java (Michener 2007). The members of this genus are characterized by their rounded marginal cell which is longer than the distance from its apex to the wing tip; scutellum convex with scutellar transverse medial carina; body without spots of white pubescence but with yellow, brown, orange or black hairs (Michener 2007, Niu et al. 2017).

Based on specimens collected from one of the northeastern Indian states, i.e., Meghalaya (25°02′ and 26°07′ N and longitudes 89°49′ and 92°50′ E and an elevation range from 60 m to 1961 m asl) and review of all available species accounts, characters used to distinguish this species (Lieftinck 1972, Niu et al. 2017, Dubitzky 2007), could be inferred that only three species of Tetralonioidella are recognized from India, including this new species. Incidentally, all three species have been recorded from Meghalaya. Literature shows that Tetralonioidella has higher species diversity in China than any other country (Niu et al. 2017). In this contribution, we provide diagnosis, description and illustrations of the Indian Tetralonioidella species. Thus, the current study with description of a new species along with a key to Indian Tetralonioidella species aims to contribute to better understanding of these slender Melectine bees of the Indian subcontinent.

Materials and methods

Random sampling with a standard insect sweep net was conducted during the daytime when insects are active. The sweepings were performed over wildflowers of Chinese Rain Bells in an undisturbed area of the Botanical Survey of India, Umiam, Meghalaya (one of the northeastern states in India). The specimens were collected and transferred to the polythene bags containing cotton soaked 100% ethanol and later killed and preserved in 70–90% ethanol. They were then relaxed on blotting paper or relaxing chamber with an airtight lid, cleaned with the help of Camel brush and then they were pinned carefully in a standard manner, i.e., through the scutum of the thorax, and stretched accordingly in such a manner that the legs are directed away from the body and wings stretched so as to make an almost 90° angle with the body for proper characterisation. The mounted specimens were then labelled with information such as: place of collection with coordinates, date of collection and collector's name. These specimens were then transferred to insect collection boxes preserved with naphthalene balls, which were further used for identification. Photographs were taken with LEICA MC190 HD digital camera attached to the LEICA M205 C stereozoom automountage microscope at various magnifications. All files were processed with Adobe Photoshop CS5 for preparation of illustrations. The morphological terminology follows that of Michener (2007). Absolute measurements were taken in millimetres (mm) for all body parts (except for Fig. 2b in μm). The following abbreviations are used throughout:

Abbreviations

Tetralonia (Tetralonioidella) Strand, 1914: 140.

Protomelissa Friese, 1914: 322. Type species: Protomelissa iridescens Friese, 1914 = Tetralonia hoozana Strand, 1914, by subsequent designation (Sandhouse, 1943: 592).

Callomelecta Cockerell, 1926: 621. Type species: Callomelecta pendleburyi Cockerell, 1926, by original designation.

Type species. Tetralonia hoozana Strand, 1914, by monotypy.

Diagnosis of the genus Tetralonioidella:

View Full Size

Tetralonioidella meghalayensis sp. n. female holotype. a. Metasoma, dorsal view. b. Mesosoma, dorsal view. c. Labrum and mandible, frontal view

Citation: Animal Taxonomy and Ecology 70, 2; 10.1556/1777.2024.12683

• Download Figure
• Download figure as PowerPoint slide

View Full Size

Tetralonioidella meghalayensis sp. n. female holotype. a. Forewing. b. Antenna. c. Head, frontal view

Citation: Animal Taxonomy and Ecology 70, 2; 10.1556/1777.2024.12683

• Download Figure
• Download figure as PowerPoint slide

View Full Size

Tetralonioidella meghalayensis sp. n. female holotype. a. Hind tarsal claw, ventral view. b. Dorsal habitus. c. Lateral habitus.

Citation: Animal Taxonomy and Ecology 70, 2; 10.1556/1777.2024.12683

• Download Figure
• Download figure as PowerPoint slide

Type material. Holotype♀, paratypes 3♀, India, Meghalaya, Ri Bhoi district, Botanical Survey of India, Umiam (25.6777° N, 91.9043° E), ca 1000 m, 27.X.2022, Collector: Pynhunlin Dohling.

Type deposition. The holotype and paratypes are deposited in National PUSA Collection (NPC), Division of Entomology, Indian Agricultural Research Institute (IARI), New Delhi-110012, India.

Floral record. Chinese Rain Bells (Strobilanthes hamiltoniana) of family Acanthaceae.

Etymology. The new species is named after the Indian state, Meghalaya, from where it was collected.

Description.

Measurements. Female: BL = 15.07 mm, HL = 3.45 mm, HW = 5.36 mm, CL = 1.93 mm; CW = 2.74 mm; FWL = 10.34 mm, HWL = 6.76 mm, ThL = 4.59 mm; ThW = 3.73 mm, MsL = 7.03 mm, MsW = 5.63 mm, OOD = 0.80 mm, IOD = 0.52 mm, EL = 3.18 mm, EW = 1.53 mm, GW = 0.90 mm.

Integument colour. Body black; galea, maxillary palpi and glossa amber yellow; mandible (Fig. 1c) basal 2/3rd olive green-brown, apical 1/3rd reddish black; labrum brownish black with two antero-lateral tuberculous light ochreous spots; clypeus reddish dark brown with a small, pale yellow apicomedial spot tapering posteriorly on lower distal portion (Fig. 1c). All other parts of head black. Antenna black, outer parts of AF1 tip and AF2 reddish yellow spots with the rest of flagellar segments dull yellowish grey ventrally (Fig. 2b). Mesosoma black; tegulae yellowish brown (Fig. 1b); axilla reddish black; veins and pterostigma dark brown (Fig. 2a); wing membrane translucent with shades of brown and papillate apically; all legs mostly reddish black with yellowish brown tarsal segments; tibial spurs brown; claws yellow basally to reddish black apically. Metasomal tergites black with amber yellow laterally; metasomal sternites reddish brown except transparent yellowish-brown line along apical margin of S1–S4; pygidial plate reddish brown basally, black apically.

Pubescence. Short to moderately long silvery-white hairs on outer margin of basal half of mandible with long piceous bristles towards condylar groove of mandibular apex; labrum (Fig. 1c) with sparse short to moderately long yellow hairs medially and row of yellow short bristles distally; clypeus with with pale yellowish long hairs laterally. Hairs all over head unbranched, yellow, except mixture of yellow with long, dark brown to black in paraocular area, frons, between lateral ocelli and vertex; gena mixture of silvery white, pale yellow and few black hairs. Pilosity around the antennal socket and scape laterally, short to long silvery white but pale yellow on scape dorsally (Fig. 2c). Mesosoma mainly covered with bicoloured hairs which are yellow basally and turning brown apically (Fig. 1b); dark tipped hairs next to the tegulae, but yellow hairs anteriorly, dark brown hairs posteriorly and mixture of dark brown with yellow hairs in between the wings; silvery white hairs on pronotum, lateral propodeum, coxa and trochanter of all legs, mesepisternum, and metepisternum. Mid and hind femora with brown hairs; hind tibia dark amber brown hairs outside (Fig. 3c), upper yellowish brown, lower black inner hairs; basitarsus complete, long, black hair with penicillus yellowish brown distally at the tip. Metasoma covered with mixture of yellow and dark brown, long, simple or branched hairs throughout; apical parts of T1–T3 with short, yellow fringe hairs obscured with long hairs from medial region of the respective tergites; long, dense, yellow tomentum on major part of T4 (Fig. 1a); T6 with long, dark brown bristles at apical and lateral ends of the pygidial plate. All metasomal sternites medially with short to moderately long, dark brown hairs and ventrally on lateral ventral regions of S2–S4 with silvery white, loose, long hairs (Fig. 3c); S6 apical black fringe with short, shiny pale yellow to long dark brown to black fringe of hairs.

Structure:

Head. Head wider than long (HW/HL = 5.368/3.448 = 1.556 mm); mandibular apex (Fig. 1c) simple but with an obscure dorsal subapical tooth; mandibular condylar groove, condylar ridge and acetabular groove with few long bristles; galea with punctation, downcurve short bristles apically; maxillary palpus six segmented with second palpomere longest, followed by fifth and sixth palpomere as shortest palpomere; labrum (Fig. 1c) broader than long (LW/LL = 1.796/0.952 = 1.874 mm), shiny, shagreen, upper two basolateral regions are yellowish, tuberculous and transparent; labral apex broadly rounded but deeply emarginated apicomedially; clypeus and supraclypeus protuberant, strongly convex in profile; clypeus (Fig. 2c) smooth and punctate; supraclypeus laterally tessellate, densely foveolate as clypeus in its lower medial region; frons rough, strongly shagreen, tessellate, protuberant, convex, sloping upwards with a weakly carinated medial longitudinal frontal line; width of compound eye greater than width of gena; antenna (Fig. 2b) long, 12 segmented, reaching beyond the tegula attaining scutellum; scape long (AS = 1.194 mm), slightly curve; pedicel short (AP = 0.112 mm); first flagellomere elongate, AF1(0.980 mm) > AF2(0.288 mm) + AF3(0.375 mm); presence of fine minute punctures on tip of AF1 and whole of AF2; terminal antennal segment AF12 is slightly longer than AF2; compound eyes parallel sided, slightly converging above (Fig. 2c); area between ocelli tessellated with fine to coarse punctations; ocello-occipital distance longer than inter-ocellar distance (OOD = 0.804 mm; IOD = 0.519 mm) and vertex tessellate with fine punctures.

Mesosoma. Mesosoma ordinarily oval (length = 4.590 mm; width = 3.732 mm); Pronotum without ridge; pronotal lobe conspicuous; scutum (Fig. 1b) dull to slightly shiny, shagreen, tessellate with fine close punctations; tegula (Fig. 1b) shiny, tessellate; convex scutellum which is dull, tessellate with fine and dense punctations; axilla short, broad, angulate and not pointed; scutellar spines absent; metanotum flat, declivous, tessellate; propodeal triangle including medial region smooth, shiny but antero-lateral regions strongly shagreen and tessellate; lateral parts of propodeum dull, tessellate, with fine small punctures; mesepisternum and metepisternum distinctly punctate and tessellate. Hind femur (FeL = 2.446 mm) shorter than tibiae (TiL = 3.282 mm), which have fine dense punctures; inner hind tibial spur straight, parallel sided lightly curved apically; hind basitarsus broad, very slightly convex from the base to the outer margin of it; inner ramus of hind tarsal claw blunt, arolium present (Fig. 3a). Submarginal cell longer (SMC = 1.204 mm) than its distance from the tip to the apex of the wing margin (1.147 mm); posterior margin of first SMC longer than that of the third SMC and first recurrent vein received near apex of second submarginal cell (Fig. 2a).

Metasoma. Metasomal width (5.633 mm) distinctly broader than mesosomal width (3.732 mm) (Fig. 1a). All tergites dull, shagreen, tessellate with distinct coarse punctures laterally; T1 (T1L = 0.552 mm) is shorter in length than T2 (T2L = 0.902 mm) (Fig. 1a) and has a broad groove on the lower inner side anteriorly with fine and shallow closely spaced punctures on dorsal side; T5–T6 dull shiny; V-shaped pygidial plate with fine punctures, apex narrowly rounded and slightly concave on lateral sides having finely reticulate-tessellate sculpture with a subapical ridge. Apical margins of sternites S1–S6 shining, with weakly defined sparse punctures and broad posterior depressions of all sternites.

Male. Unknown

Diagnosis of T. meghalayensis.

The new species, T. meghalayensis is structurally quite reminiscent of one of the Oriental species reported from China and India, namely, T. himalayana (Bingham, 1897) (Fig. 5d) in its anthophoriform body shape, body pubescence and colouration. The new species can be distinguished from its congeners by having the following specific characteristics: T4 (Fig. 1a) widely covered with yellow tomentum below the simple dark hairs, delineating a subtriangular posterior surface and tapering basally (such a feature is absent in all other known species, such as T. himalayana (Fig. 5d), etc) and absence of scutellar spines (Fig. 1b) (present in all other species such as Tetralonioidella wuae Niu & Zhu, 2017 (Fig. 5f)). Its other distinctive features are broad labrum (Fig. 1c) almost twice as broad as long (as in T. tricolor (Lieftinck, 1972), but longer in T. himalayana (Fig. 5d)); labral apex (Fig. 1c) more deeply incised apicomedially (similarly to T. himalayana (Fig. 5b) and Tetralonioidella damenglongensis Niu & Zhu, 2017 compared with shallowly emarginated in T. tricolor (Fig. 5a), Tetralonioidella longqiensis Niu & Zhu, 2017, (Tetralonioidella vulpecula) Lieftinck, 1944, T. hoozana and without emargination in T. wuae (Fig. 5f); antenna long (Fig. 2b), reaching beyond the tegulae, as in T. damenglongensis, T. wuae compared to short antenna, reaching front margin of tegula in T. longqiensis and T. tricolor and reaching middle of tegula in Tetralonioidella heinzi Dubitzky, 2007 (Fig. 5g). Mesosoma pubescence (Fig. 1b) is wholly bicoloured, i.e., yellow with dark brown to black, as commonly in the genus Tetralonioidella, with the exception of having unicoloured pubescence like densely yellow in T. tricolor, yellowish orange in T. heinzi (Fig. 5g) and T. wuae, fox red in T. hoozana and xanthine orange in Tetralonioidella pendleburyi and T. vulpecula (Lieftinck, 1972) and forewing (Fig. 2a) with distinct papillae apically as in T. himalayana, T. longqiensis and many others except (with only numerous minute hairs apically) in T. heinzi (Fig. 5g) and T. wuae.

Discussion

The first species reported from the country is T. himalayana, from Kumaon hills, Uttarakhand (Bingham 1897) followed by T. tricolor from Meghalaya. Tetralonioidella meghalayensis is found to be closely related to Tetralonioidella formosana Cockerell, 1911, which is today treated as conspecific with T. himalayana. In spite of the fact that Lieftinck (1972) found no convincing characteristics to support the split between T. formosana and T. himalayana, he treated them as two distinct species with only vague differences in pubescence colouration, features of the labrum and propodeal triangle. Therefore, in this paper, for comparison, we have studied both species under the present valid name of Tetralonioidella himalayana Bingham, 1897. Lieftinck (1972) described T. tricolor which was the second species to its genus in the country but first to be discovered from Meghalaya, India. However, the new species is not closely related to T. tricolor but it is structurally quite reminiscent of one of the Oriental species reported from China and India, namely, T. himalayana in its anthophoriform body shape, body pubescence and colouration. Some of its morphological traits are clearly distinctive from other species and they have been briefly mentioned in the diagnosis above.

The potential distribution maps of this new species show that T. meghalayensis could also be established in more other Indian states, according to the distribution records in available literature. Interestingly, the known distribution of all the species under the genus Tetralonioidella have been limited to the Oriental region only. It is hoped that by publishing a detailed description of this new species included in the keys to the species of Tetralonioidella found in India, that the additional specimens, including its male, will be discovered through future survey work. Table 1 shows the checklist of the genus Tetralonioidella Strand, 1914 from India and its distribution map is shown in Fig. 4. The Northeastern region of India, including Meghalaya, has rich biodiversity found in the area, ranging from alpine scrubs to tropical rainforests, which contributes to the large and varied Oriental fauna and this requires more systematic and faunistic studies in the country. Thus, it is possible that numerous other bee species may await recognition.

View Full Size

Updated distribution map of the species under the genus Tetralonioidella found in India (respective states of the species mentioned in the checklist)

Citation: Animal Taxonomy and Ecology 70, 2; 10.1556/1777.2024.12683

• Download Figure
• Download figure as PowerPoint slide

Key to the species of Tetralonioidella Strand, 1914 of India

(Couplet no. 6 and 7 of Lieftinck, 1972 modified)

1. 1.Maxillary palpi with third segment longest; labrum (Fig. 5a) short, twice as long as wide, its apical margin shallowly rounded notched at the middle; dorsal view of antennal scape is devoid of tuft of long raised hairs, AS3 shorter than AS4; scutellar spines present; inner ramus of mid and hind tarsal claws squarish; vestigial tarsal arolia…………….….T. tricolor (Lieftinck, 1972)
   1. -Maxillary palpi variable; labrum short or long, either twice as long as wide or slightly shorter, its apical margin deeply rounded notched in the middle; dorsal view of antennal scape (Fig. 2c, Fig. 5c) dense hairy with presence of tuft of long raised hairs, AS4 shorter than AS3; scutellar spines present or absent; inner ramus of mid and hind tarsal claws laterally compressed, not squarish (Fig. 3a); conspicuous tarsal arolia……………………….………………2
2. 2.Labrum (Fig. 5b) is 1.3 times broader than long; scutellar spines present, may or may not be fully covered by long pale pubescence; scutum (Fig. 5d) densely haired medially; propodeal triangle smooth to slightly wrinkled laterally; T4 (Fig. 5d) with ordinarily long hairs as on rest of tergites, without yellow tomentum ………………………T. himalayana (Bingham, 1897)
   1. -Labrum (Fig. 1c) is 1.8 times broader than long; scutellar spines (Fig. 1b) absent; scutum (Fig. 1b) sparsely haired medially; propodeal triangle smooth, not wrinkled laterally; T4 (Fig. 1a) widely covered with yellow tomentum below the simple dark hairs, delineating a subtriangular posterior surface and tapering basally………………………………………………………………………………………………T. meghalayensis (Dohling & Dey sp. n.)

View Full Size

a. Labrum of T. tricolor (Lieftinck, 1972) (female from fig. 4 of Lieftinck 1972), b. Labrum of T. himalayana (male, same as for female shown as P. formosana, its senior synonym, from fig. 1 of Lieftinck, 1972), c. Antenna of T. himalayana (male, same as for female, from fig. 2 of Lieftinck, 1972), d. Dorsal habitus of T. himalayana (female from fig. 1.f. of Ghosh et al. 2023), e. Mesosoma of T. wuae, showing the scutellar spines obscured by the pubescence (female from fig. 22.f. of Niu et al. 2017), f. Labral apex without emargination medially of T. wuae (female from fig. 22.c of Niu et al. 2017), g. Lateral habitus of T. heinzi (female from fig. 1 of Dubitzky 2007)

Citation: Animal Taxonomy and Ecology 70, 2; 10.1556/1777.2024.12683

• Download Figure
• Download figure as PowerPoint slide