Bogidiella hindustanica, Sidorov & Reddy & Shaik, 2018

Sidorov, Dmitry, Reddy, Yenumula Ranga & Shaik, Shabuddin, 2018, Groundwater amphipods (Crustacea, Malacostraca) of India, with description of three new cavernicolous species, Zootaxa 4508 (3), pp. 403-426 : 413-414

Bogidiella hindustanica , new species

Figures 2B , 6–8

Diagnosis. Slender, small-sized amphipod of typical bogidiellid habitus (sexual dimorphism unknown); distinguished by shallow coxal plates (wider than deep); posterodistal corners of pleonal plates I–III sub-acute; antenna I longer than antenna II; accessory flagellum of antenna I long, 3-articulate; mandibular molar welldeveloped; maxilla I palp normal, 2-articulate; propodi of both gnathopods almond-shaped, propodus of gnathopod I somewhat large; pereopods V and VI normal; coxal gills present on pereopods IV and V (observed on a damaged specimen). Largest female 2.75 mm.

Material examined. Holotype MNHN-IU- 2018-50. INDIA: ♀ ca. 2.75 mm, oostegites developed, setose, Kapiladevi caves, cave-pool sediments, 19.532333, 78.995028, elevation 324 m, Telangana state, coll. Shabuddin Shaik, 12 th May 2013. Paratypes MNHN-IU- 2018-51: 1 broken ♀ ca. 2.75 mm, oostegites developed, setose, 3 juveniles, ca. 1.5 mm fragment; same data as for holotype. Accompanying fauna: Indoniphargus subterraneus sp. n. ( Amphipoda : Austroniphargidae ) described below.

Etymology. The specific epithet hindustanica (Latin) is an adjective, derived from the historical toponym, Hindustan, for the Indian subcontinent. Gender feminine.

Description of holotype MNHN-IU- 2018-50. GENERAL BODY MORPHOLOGY ( Figs 2B , 6A , 7D , 8A, E, I ). Body unpigmented, smooth. Head as long as first pereon segment; rostrum indistinct, interantennal lobe evenly rounded apically; eyes absent. Pleonal plates I–III with sub-acute posterodistal corners and with single seta on posterior margin each, ventral margin of plates unarmed. Telson subquadrate, narrowed apically, with apical margin straight, bearing 2 tiny setae apically. ANTENNAE ( Figs 2B , 6A ). Antenna I ca. 40% of body length; primary flagellum of 7 articles, each article with 2 or 3 setae, aesthetascs present on each of 5 distal articles; ratios of peduncular articles 1–3 1:1:0.6; proximal article of peduncle with a few thin setae on ventral margin; accessory flagellum long, 3-articulate. Ratio of lengths of antenna I to antenna II is 1:0.77; flagellum of antenna II with 5 articles, each article sparsely setose, articles 1, 2 and 5 bearing slender semitransparent, rod-like structures (probably aesthetascs); peduncular article 4 slightly longer than article 5; flagellum 60% shorter than peduncle (articles 4+5); last 2 peduncular articles with sparse setae; gland cone not markedly elongate. MOUTH PARTS ( Figs 6 B–H). Labrum roundish, epistome produced. Inner lobes of paragnath well developed, outer lobes broadly spaced, sparsely setose apically; mandibular process narrow. Left mandible: incisor with 5 teeth, lacinia mobilis consisting of 2 finely denticulate plates of similar size; 2 or 3 densely plumose spines between lacinia and molar process; molar produced and triturative. Right mandible: incisor with 5 teeth, lacinia mobilis with 5 teeth, a row of 3 densely plumose spines between lacinia and molar process; molar similar to that of left mandible; mandibular palp article 2 about twice as long as palp article 3; proximal palp article without seta; article 2 with 1 seta on inner margin; distal article truncated, with 3 long unequal setae on apex, and numerous fine setae near lateral margin on distal half of article. Maxilla I palp 2-articulate, with 3 long setae of equal length on apex (palps symmetrical); outer plate with 7 finely pectinate spines; inner plate with 2 faintly plumose setae. Maxilla II inner plate broader than outer one, with 6 apical setae; outer plate with 7 long setae of varying size apically. Maxilliped outer plate evenly rounded apically, with 3 long, simple apical spines and 2 stiff setae on lateral face, and 2 long lateral setae in distal part; inner plate with 2 bifid apical spines and 1 stiff naked seta, 2 setae located on ventral face; palp 4- articulate; palp article 2 longest, nearly straight on outer margin, slightly convex on inner margin, with a row of 5 long, simple setae along inner margin; article 3 0.7× as long as article 2, with sharply pointed cuticular projection distally and bearing a set of 4 long, stiff setae in ventrodistal position and 2 thin setae in dorsodistal position; article 4 longer than preceding article, distinctly curved and tapering distally, with 1 dorsal seta, and 1 seta at base of nail, inner margin pubescent, nail sharply pointed, 0.25× length of pedestal. COXAL PLATES, OOSTEGITES AND GILLS ( Figs 2B , 7A, D ). Coxal plates I–VII wider than long, without overlapping one another; coxa V largest; coxal plates V–VII progressively smaller posteriad, sub-triangular, plates V and VI bearing 1 stiff seta each posteriorly. Oostegites (brood plates) small, progressively larger posteriad, linear, setose with long setae on pereopods II–V. Coxal gills ovate, stalked on coxae IV and V. GNATHOPOD I (GII missing) ( Figs 2B , 7A ). Gnathopod I, basis oblong, broadest medially, with 1 long seta on posterior margin; merus with 2 stiff setae on distoposterior margin, posterior surface densely spinose; carpus triangular, with 2 setae of equal length on pointed spinose distoposterior lobe; propodus oblong, about 2.0× longer than broad, palmar margin slightly convex, 3.0× longer than posterior margin, palmar angle indistinct, armed with 3 strong spines and 1 long seta; anterior margin with 1 seta, and a group of 3 setae anterodistally; palm armed with 9 or 10 stiff, tiny notched setae along inner and outer faces; dactylus falcate, about 60% length of propodus, with 2 notches accompanied by thin seta on inner face, demarcation of nail indistinct. PEREOPODS III and IV (PV through PVII missing) ( Figs 2B , 7B, C ): lacking lenticular organs; structurally similar, bases rather long, fusiform, and each with 2 setae on distal margin; dactyli about 0.3× length of corresponding propodi. PLEOPODS AND UROPODS ( Figs 2B , 8 B–H). Pleopods I–III subequal; peduncular articles linear, in ratios of ca. 0.9:1.0:0.9, with 2 retinacula each; inner rami reduced, 1- articulate, shorter than basal width of article 1 of outer ramus; outer ramus 3-articulate, fringed with long, plumose setae at distal end of each article. Uropod I peduncle without basofacial spine and with 1 dorsomedial spine; exopodite as long as endopodite; endopodite length 0.5× peduncle; rami straight, each ramus armed with 3 spines apically (1 of them much larger, sword-shaped). Uropod II peduncle with 1 dorsomedial spine distally; exopodite to endopodite length 0.7:1.0; endopodite as long as peduncle; rami straight, each ramus armed with 3 or 4 spines apically (1 of them much larger, sword-shaped). Uropod III long, with peduncle twice shorter than rami, armed with 2 notched spines on apex; endopodite with 5 singly inserted spines along outer margin and 3 long, sharply pointed apical spines; exopodite with 5 singly inserted notched spines along margins and 6 apical spines (2 of them much larger, sword-shaped).

Variation. No morphological variation was observed in two damaged adult female specimens of the same body length. Three probably juvenile females measuring ca. 1.1–1.5 mm in body length and without clearly visible oostegites (brood plates) were found in the material examined. The specimens showed no ontogenetic variation in the morphology of appendages except for palms of both gnathopods (see Figs 7E, F ) being poorly armed, and articles more profusely covered with minute bristles. Further, the study of these juvenile specimens leaves no doubt that B. hindustanica sp. n. has normal pereopods V and VI and so cannot be assigned to Orientogidiella gen. n.

Sexual dimorphism. Males unknown.

Distribution and ecology. Bogidiella hindustanica sp. n. is known only from its type locality (see Fig. 1 ).

Remarks. Bogidiella hindustanica sp. n. is assigned to the lindbergi -group (group D, which contains species for which sexually dimorphic characters are unknown, see Koenemann & Holsinger 1999), and to this group we also attribute B. totakura Senna et al., 2013 because the sexual dimorphism of this species remains still enigmatic. Bogidiella hindustanica sp. n. closely resembles B. totakura in possessing the following features: normal pereopods V and VI; 3-articulate accessory flagellum on antenna I; broad mandibular molar and almost similar form and armature of mandibular palps; and uropods I and II rami with 3 or 4 apical spines (1 of them much larger, sword-shaped). B. hindustanica sp. n. can, however, be distinguished from the latter species by (character states of B. totakura in parentheses): pleopods I–III inner rami reduced, 1-articulate (inner rami absent); and entire apical margin of telson has 2 minute setae (apical margin notched, bearing 2 large spines).

Figures

FIGURE 1. Height map of India showing geographic distribution of subterranean amphipods. Question mark (?) indicates collections of undescribed specimens of Bogidiella sp. reported in Holsinger et al. (2006). Asterisk (*) indicates new sample sites.

FIGURE 2. Habitus of examined specimens: (A) Orientogidiella reducta gen. n., sp. n., holotype MNHN-IU-2018-47, male, 5.5 mm; (B) Bogidiella hindustanica sp. n., holotype MNHN-IU-2018-50, female, 2.75 mm; (C) Indoniphargus subterraneus sp. n., holotype MNHN-IU-2018-52, female, 5.2 mm.

FIGURE 6. Bogidiella hindustanica sp. n., holotype MNHN-IU-2018-50, female, 2.75 mm: (A) head and antennae; (B) mandible, right; (C) mandible, left; (D) labrum (=upper lip); (E) paragnaths (=lower lip); (F) maxilla I; (G) maxilla II; (H) maxilliped. Scale bars 0.1 mm.

FIGURE 7. Bogidiella hindustanica sp. n., (A–D) holotype MNHN-IU-2018-50, female, 2.75 mm: (A) gnathopod I; (B) pereopod III; (C) pereopod IV; (D) thoracic segments II–VII; (E, F) paratype MNHN-IU-2018-51, juvenile, 1.2 mm: (E) gnathopod I; (F) gnathopod II. Scale bars 0.1 mm.

FIGURE 8. Bogidiella hindustanica sp. n., holotype MNHN-IU-2018-50, female, 2.75 mm: (A) pleonal plates I–III; (B–D) pleopods I–III; (E) urosome; (F) uropod I; (G) uropod II; (H) uropod III; (I) Telson. Scale bars 0.1 mm.