Diagnostic remarks

The newly described species can be placed in the family Siphonorhinidae based on the following combination of characters: pear-shaped head, with mouthparts not extending into a beak (Figs. 2A, 3B), while it extends into a beak in Siphonophoridae (Fig. 2B) (see Read & Enghoff 2009); gnathochilarium divided into separate plates (Fig. 4D), while all plates are fused in extant Siphonophoridae (see Read & Enghoff 2019: 10, fig. 3E); antennomere 2 twice as long as antennomere 3 (Figs. 3B, 5A); antennae elbowed between antennomeres 3 and 5 (Figs. 3B, 5A), vs. straight in Siphonophoridae (Fig. 2B) (see Read & Enghoff 2009).

Type species: Siphonorhinus pallipes Pocock, 1894 (Indonesia: Java: Bogor).

Included species

Siphonorhinus angustus Pocock, 1894 (Indonesia: Java).

Siphonorhinus cingulatus (Attems, 1936) (India; Vietnam).

Siphonorhinus coniceps (Attems, 1936) (Cambodia; India).

Siphonorhinus larwoodi (Turk, 1947) (India).

Siphonorhinus latus Silvestri, 1895 (Indonesia: Sumatra).

Siphonorhinus pallipes Pocock, 1894 (Indonesia: Java).

Siphonorhinus pellitus (Attems, 1930) (Indonesia: Flores).

Siphonorhinus robustus (Attems, 1938) (Laos; Vietnam).

Siphonorhinus parambikulam Anilkumar et al., sp. n. (India).

Diagnostic remarks

The newly described species is assigned to the genus Siphonorhinus based on the following characters: head shape more acuminate (Fig. 4A) and less rounded than in Illacme (Marek et al. 2023: 273, fig. 1A) and Notiorhinus (Moritz & Parra-Gómez 2023a: 570, fig. 3A). It differs from Notiorhinus (Moritz & Parra-Gómez2023a: 570, fig. 3C), Illacme (Marek et al. 2016: 9, fig. 3D), and Madagascarhinus (Wesener 2023: 170, fig. 4F), in which the salivary glands open in a single field above the labrum, and from the new species of Siphonorhinus by having its salivary gland openings arranged in two fields ventrally at the labral margin (Fig. 4F). Antero-lateral sides of gnathochilarial stipes with three macrosetae (Fig. 4C), while such setae are absent in the other five genera. However, the arrangement of the salivary gland openings and macrosetae have to be confirmed for the remaining Siphonorhinus species. Antennomere 6 strongly rounded and bulged (Fig. 5A, B), while it is cylindrical in Illacme (Marek et al. 2012: 90, fig. 8a), Nematozonium (Shelley & Hoffman 2004: 220, fig. 1), Madagascarhinus (Wesener 2023: 170, fig. 4D), and Notiorhinus (Moritz & Parra-Gómez 2023a: 570, fig. 3E), and weakly round/cylindrical and bulged in Kleruchus (Attems 1938: 296, fig. 194). Sensilla basiconica on antennomeres 5 and 6 in circular sensory pits (Fig. 5B), as reported for other Siphonorhinus (Attems 1930, 1938) and Kleruchus (Attems 1938), whereas these are not in a defined pit in Illacme (Marek et al. 2012: 90, fig. 8a) and Madagascarhinus (Wesener 2023: 170, fig. 4D), absent on antennomeres 5 and 6 in Nematozonium (Shelley & Hoffman 2004), and absent on antennomere 5 in Notiorhinus (Moritz & Parra-Gómez 2023a: 570, fig. 3E). Coxa and sternite of leg 1 fused (Fig. 6C) as in Siphonorhinus robusta (Attems, 1938) (Attems 1938: 302, fig. 213), Notiorhinus, in which the coxal portion is rectangular (Moritz & Parra-Gómez 2023a: 570, fig. 3G), and Madagascarhinus, in which it is triangular (Wesener 2023: 168, fig. 3A). The sternite and coxa of leg 1 are unfused in Kleruchus (Attems 1938: 296, fig. 193). Presence of paranota in Siphonorhinus (Figs. 3D, 5E, F) and Kleruchus (see Attems 1936, 1938), while they are absent in all other genera of the family: Illacme (Marek et al. 2012: 86, fig. 2), Nematozonium (Shelley & Hoffman 2004: 220, fig. 1), Madagascarhinus (Wesener 2023: 171, fig. 5A), and Notiorhinus (Moritz & Parra-Gómez 2023a: 571, fig. 4B). Last podomere of posterior gonopod extending in Siphonorhinus into a thin, long filament, dividing apically into two leaf-shaped styliform articles (Fig. 7F), whereas it bifurcates into three styliform articles in Madagascarhinus andasibensis Wesener, 2023 (Wesener 2023: 173, fig. 7B) and Notiorhinus floresi Moritz & Parra-Gómez, 2023a (Moritz & Parra-Gómez 2023a: 572, fig. 5F), and into 3–5 styliform articles in Illacme (Marek et al. 2023). In Nematozonium, the apical region of the extended podomere of the posterior gonopod is bifurcated into three spine-like processes, with a basal spine curving above the other two (Shelley & Hoffman 2004: 220, fig. 3), while in Kleruchus the last podomere of the posterior gonopod appears as three spine-like structures (Attems 1938: 298, fig. 203).

Diagnosis

As most Siphonorhinus species descriptions are 80–120 years old, incomplete, and based on female specimens, the following are some characters that could be unique for the species described below and should be checked for in other Siphonorhinus species: ventral side of labrum with two fields of salivary gland openings (Fig. 4F); collum laterally forming a triangular margin (Fig. 4B); legs 1–3 (Fig. 6C–E) and a few posterior body legs with a small accessory claw (Fig. 6A, B); base of posterior gonopod podomere 7 with a small spine (Fig. 7A, F).

Siphonorhinus parambikulam sp. n. is an elongate Siphonorhinus species with a flattened body and lateral paranota; with 58 tergites plus telson; ∼13 mm long and ∼1.15 mm wide, and orange-brown in color (Figs. 2A, 3C, F). The holotype of Siphonorhinus parambikulam sp. n. differs in tergite number from S. angustus (104 tergites), S. cingulatus (83), S. coniceps (68), S. latus (67), S. pallipes (74–94), and S. robustus (63), and in overall size, with these six species being much longer (length 23–43 mm) and wider (width 2.0–4.6 mm). Siphonorhinusparambikulam sp. n. also differs from the other seven Siphonorhinus species in its color: S. larwoodi is pale brownish-white, S. cingulatus brown with three dark stripes dorsally, S. coniceps and S. pellitus yellowish-brown, S. latus reddish-brown, S. pallipes grayish-black/dirty-white with a dark stripe dorsally, and S. robustus dark reddish-brown with a black-eel-striped pattern dorsally.

Siphonorhinus parambikulam sp. n. differs from the incompletely described S. larwoodi from the Himalayas in the higher segment number (58 vs. 40 in S. larwoodi), the longer antenna (shorter than the head in S. larwoodi), and the number of macrosetae (3 vs. 2 in S. larwoodi) on the lateral margin of the gnathochilarial stipes (Fig. 4C). Siphonorhinus parambikulam sp. n. differs in the number of tergites from the other two Indian species described from the Himalayas, S. cingulatus (58 vs. 83) and S. coniceps (58 vs. 68). Siphonorhinus parambikulam sp. n. differs from S. pellitus in the shape of the styliform articles on the posterior gonopod (leaf-shaped vs. claw-shaped in S. pellitus) and in the number of gonopod podomeres (anterior gonopod = six vs. five in S. pellitus; posterior gonopod = seven vs. six in S. pellitus) (see Attems 1930: 158, figs. 58–61). Siphonorhinus parambikulam sp. n. differs from S. robusta by the absence of elongated apical lamellae on podomere 6 of the anterior gonopod (Fig. 7A vs. Attems [1938, fig. 217]) and the bifurcation of the apical podomere of the posterior gonopod into a pair of leaf-shaped styliform articles (Fig. 7F) vs. a wart-like structure in S. robusta (see Attems 1938, fig. 218).

Etymology

The species epithet parambikulam, a noun in apposition, refers to the type locality of the species, Parambikulam Tiger Reserve, Kerala, India.

Type material

Holotype ♂ (Fig. 2A): ZFMK-MYR 9076, India, Prov - ince Kerala, Palakkad-Thrissur District, Parambikulam Tiger Reserve, evergreen forest, underside of a rotting log, hand collection, 10°23'42.3”N 76°39'07.2”E, 555 m, 2.XII.2019, leg. A. A. POOJA, P. P. SUDHIN, R. S. ABHIJITH. Zoological Survey of India, Calicut, Kerala, India (ZSI).

Description

Male holotype. Measurements: after dissection, 58 tergites + telson, ∼13 mm in length and ∼1.15 mm in width. [A few body rings (+5) were dissected for barcoding prior to photographing the specimen.]

Coloration [after 4 months in ethanol]. Head light-orange, antennae white, tergites orange-brown, legs creamish-white (Fig. 2A).

Head. Pear-shaped, ∼0.6 mm in length and ∼0.5 mm in width; almost three times as long as collum. Epicranium slightly arching above antennal base (Figs. 3B, 4B). Densely setose except for forehead (Fig. 4A, C), laterally covered by tubercles (Fig. 4B). Salivary gland openings in fields of > 30 pores on both sides of the labrum, facing downwards (Fig. 4F). Gnathochilarium divided, with central mentum, paired flap-shaped lamellae lingualis anterior to the mentum, paired stipites lateral to the mentum anteriorly, and lamellae lingualis apically with sensory palps (Fig. 4D–F). Gnathochilarium anteriorly deeply divided between the lamellae lingualis, exposing preoral chamber. Anterior setae of mentum and lamellae lingualis apically flattened and spiraling (Fig. 4D–F). Three macrosetae on antero-lateral margin of gnathochilarial stipes (Fig. 4C). Mandibles internalized, not visible externally. Mandibular gnathal lobe elongated, mesal surface of each gnathal lobe covered by serrated structures (pectinate lamellae) facing each other, laterally with a tuft of spines (Fig. 4F). Antennae long, reaching tergite 5 (Fig. 3B), elbowed between antennomeres 3 and 5 (Figs. 3B, 5A). Seven antennomeres + apical disc (Fig. 5A). Relative length of antennomeres: 6>2>5>3=4>1>7. Antennomere 2 longer than wide, antennomeres 3–5 cup-shaped, antennomere 6 rounded, bulged, and widest of all, antennomere 7 retracted within antennomere 6 (Fig. 5B, D). Antennomeres 1–3 dorsally setose, antennomere 6 densely setose. All antennomeres with small tubercles, fewer on anterior margins (Fig. 5A). Ventro-lateral anterior margin of antennomeres 5 and 6 with circular, sunken-in sensory pit. Sensory pit on antennomere 6 more circular than on antennomere 5, with sensilla basiconica inside (Fig. 5B, C). Sensory pits on antennomere 5 with 41 (left antenna) and 31 (right antenna) sensilla basiconica. Sensory pit on antennomere 6 with 49 (left antenna) and 28 (right antenna) sensilla basiconica (Fig. 5B; for more SEMs, see Supplementary Material). Apical disc with 4 apical cones and 3 clusters of spiniform sensilla basiconica, lateral cluster with 15 sensilla basiconica, anterior cluster with 2 sensilla basiconica, and posterior cluster with 4 sensilla basiconica, projecting between apical cones (Fig. 5D).

Collum. Trapezoidal in dorsal view, slightly covering epicranium. Twice as long as following tergites (Fig. 3B, C). Triangular in lateral view. Densely setose and completely covered with tubercles (Fig. 4B).

Tergites. Free from pleurites and sternites (Fig. 6A, B). Tergites 2–4 ca. half as long as following tergites (Fig. 3B). Prozonites covered by preceding metazonite. Prozonites glabrous, anterior 3/4 covered with scales, posterior 1/4 with tubercles. Metazonites twice as long as prozonites (Fig. 5F). Metazonites arched, laterally extending into paranota, densely setose, and completely covered with tubercles (Fig. 5E, F). Paranota oriented posteriad and slightly arching posteriad from tergite 7. Paranota with ozopores from tergite 5 to tergite 57 (Fig. 3B, E). Ozopore of tergite 5 positioned close to lateral-anterior margin of paranota. Ozopore of following tergites positioned some distance from lateral-posterior margin of paranota (Figs. 3B, E, 5F). Ozopore opening facing dorsally, slightly elevated, encircled by a row of setae and surrounded by spine-like tubercles (Fig. 5F, G). Tergite 58 (last tergite) twice as long as and narrower than the preceding tergites (Fig. 3E); apodous, paranota triangular and extending posteriad (Figs. 3F, 6B).

Pleurites. Separated from tergites by a clear division (Fig. 6B). Pleurites almost rectangular, separated into prozonite and metazonite. Prozonite glabrous, covered with scales, like the tergal prozonite. Metazonite covered with tubercles and setae, like the tergal metazonite (Fig. 5H).

Sternites. Free, separated from pleurites. Triangular, posterior margin with two excavations to accommodate the associated legs. Covered with tubercles and a few setae laterally. Medial sternal ridge directed ventrally, with few setae anteriorly. Spiracles circular, open, slightly elevated, positioned lateral to legs (Fig. 6A).

Telson. Preanal ring narrower than body rings, forming complete ring. Completely covered with tubercles, densely setose. Paraprocts oval, tubercles absent in middle, with setae crossing over at opening. Hypoproct semi-hemispherical, small, 1/5 of length of paraproct (Fig. 6B).

Legs. Leg 1 slightly longer and thicker than following legs, coxa fused with sternite, with 5 free podomeres, prefemur triangular distally. Setae prominent mesally (Fig. 6C). Leg 2 with 6 podomeres (free coxa), setose mesally. Tibia and tarsus densely setose, with long setae mesally (Fig. 6D). Seven podomeres from leg 3 onwards, trochanter and coxal sac present (Fig. 6F). A few posterior legs devoid of coxal sac (Fig. 6B). Relative length of podomeres of midbody leg: femur>tarsus>prefemur>coxa >postfemur=tibia>trochanter (Fig. 6A). Claw of legs 1–4 and few posterior legs divided, with large dorsal part and short ventral part (accessory claw) (Fig. 6A, D, E). Accessory claw longer and thicker on midbody legs, reaching 2/3 of dorsal part in length (Fig. 6G).

Male sexual characters. Paired pseudopenes on coxae of leg 2, conical, carrying gonopores (Fig. 6D, F). Legs 9 and 10 modified into anterior and posterior gonopods (Figs. 3B, 7A). Anterior gonopod. Modified leg 9. Sternite rectangular, posterior margin excavated to hold gonopod anteriorly. Medial sternal ridge less prominent than on other legs, with 2 or 3 setae anteriorly. Tubercles confined to lateral and posterior margins. Spiracles circular, open, positioned laterally (Fig. 7B). With six podomeres; twice as thick as posterior gonopod. Podomeres 1 and 2 forming a rounded, stout base, tapering from podomere 3. Relative length of podomeres: a6>a4>a1>a3>a5>a2 (Fig. 7C). Podomeres 1–3 with a few setae. Podomeres 4 and 5 with a row of setae. Podomere 6 completely covered with setae, a few anterior setae apically serrated and twisted (Fig. 7A, C, E). Podomeres 3–6 extending mesad into a shovel-shaped structure. Setae at margin of shovel-shaped structure thicker than remaining setae. Apical region of podomere 6 tapering to a funnel-shaped structure, basally curving, forming a cup-like structure (Fig. 7A, B, E). Posterior gonopod. Modified leg 10. Sternite surface covered with scales. With seven podomeres. Relative length of podomeres: p7>p4>p1>p6>p5>p2=p3. Podomeres 1–3 stout and wide (Fig. 7C). Tapering from podomere 4. Podomere 6 cylindrical (Fig. 7D). Podomeres 4 and 5 mesally with few short setae (Fig. 7A). Base of podomere 7 with a small spine on a wart-like structure (Fig. 7A, F). Podomere 7 extending into a thin, long branch, apically divided into 2 styliform articles (upper and lower) with leaf-shaped tip (Fig. 7A, C, F).

Female unknown.

Material examined

Assigned to Siphonophoridae based on the following features: head extending into beak; gnathochilarium not divided; antennae straight, not elbowed as in Siphonorhinidae; body slenderer than in Siphonorhinidae (Fig. 2A, B) (Enghoff et al. 2015).]

Barcoded specimens. India, Kerala Province: 1♂, Idukki District, Mannavan Shola, Annamudi Shola National Park, high altitude montane forest, hand collection (10°10′54.5″N, 77°11′25.8″E), 2140 m, 18.XI.2019, leg. A. A. POOJA, K. ULLAS (ZFMK-MYR 09048). – 1♂ (ZFMK-MYR 09049). – 1♀(ZFMK-MYR 09050). – 1♀ (ZFMK-MYR 09051). – 1♀ (ZFMK-MYR 09052). – 1♀ (ZFMK-MYR 09053). – 1♂, 19.XI.2019, leg. A. A. POOJA, K. S. NAFIN, K. ULLAS (ZFMK-MYR 09054). – 1♀(ZFMK-MYR 09055). – 1♀, Idukki District, Idli motta Shola, Annamudi Shola National Park, high altitude montane forest, near grassland, hand collection (10°10′09.5″N, 77°10′58.1″E), 2345 m, 20.XI.2019, leg. A. A. POOJA, K. ULLAS (ZFMK-MYR 09056). – 1♀, Idli motta Shola, Annamudi Shola National Park, high altitude montane forest (10°10′09.6″N, 77°10′22.2″E), 2471 m, (ZFMK-MYR 09057). – 1♂ (ZFMK-MYR 09058). – 1♂(ZFMK-MYR 09059). – 1♂ (ZFMK-MYR 09060). – 1♂ (ZFMK-MYR 09061). – 1♀ (ZFMK-MYR 09062). – 1♀, Winkler extraction (ZFMK-MYR 09063). – 1♂, Idukki District, Pambadum Shola National Park, high altitude montane forest, hand collection (10°08′00.3″N, 77°15′13.6″E), 1818 m, 21.XI.2019, leg. A. A. POOJA, K. S. NAFIN, K. ULLAS (ZFMK-MYR 09064). – 1♀(ZFMK-MYR 09065). – 1♂ (ZFMK-MYR 09066). – 1♂ (ZFMK-MYR 09067). – 1♂ (ZFMK-MYR 09068). – 1♂, Pambadum Shola National Park, high altitude montane forest, rain shadow (10°07′55.4″N, 77°15′44.1″E), 1970 m, 22.XI.2019, (ZFMK-MYR 09069). – 1♂ (ZFMK-MYR 09070). – 1♂, Idukki District, Kadalar Shola, Eravikulam National Park, high altitude montane forest, Winkler extraction (10°08′24.3″N, 77°02′39.3″E), 1703 m, 12.XII.2019, leg. A. A. POOJA, J. JITHIN (ZFMK-MYR 09071). – 1♀ (ZFMK-MYR 09072). – 1♂ (ZFMK-MYR 09073), Eravikulam National Park, Erachilpara waterfalls, hand collection (10°10′28.0″N, 77°05′20.1″E), 1929 m, 13.XII.2019. – 1♀(ZFMK-MYR 09074). – 1♀ (ZFMK-MYR 09075). – 1♂, Kollam District, Shendurney Wildlife Sanctuary, Sasthamnada Myristica Swamps, Winkler extraction (8°49′14.3″N, 77°02′50.6″E), 160 m, 19.XII.2019, leg. A. A. POOJA, P. P. SUDHIN, R. S. ABHIJITH (ZFMK-MYR 09077). – 1♂ (ZFMK-MYR 09078). – 1♂, Shendurney Wildlife Sanctuary, Dharaphabhana chappath, mix of evergreen and deciduous forest, Winkler extraction (8°52′40.1″N, 77°04′55.9″E), 181 m, 20.XII.2019, leg. P. P. SUDHIN, R.S. ABHIJITH (ZFMK-MYR 09079). – 1♂, Shendurney Wildlife Sanctuary, Onakathodu, Kadalar range, semi evergreen bordered with moist deciduous forest, Winkler extraction (8°54′06.1″N, 77°06′25.6″E), 174 m, 22.XII.2019, leg. A. A. POOJA, P. P. SUDHIN, R. S. ABHIJITH (ZFMK-MYR 09080). – 1♀(ZFMK-MYR 09081). – 1♂ (ZFMK-MYR 09082).

Non-barcoded specimens. India, Kerala Province: – 1♀, Idukki District, Mannavan Shola, Annamudi Shola National Park, high altitude montane forest, hand collection (10°10′54.5″N, 77°11′25.8″E), 2140 m, 18.XI.2019, leg. A. A. POOJA, K. ULLAS (ZFMK-MYR 09503). – 1♂, 5♀, Idli motta Shola, Annamudi Shola National Park, high altitude montane forest, hand collection (10°10′09.6″N, 77°10′22.2″E), 2471 m, 20.XI.2019, leg. A. A. POOJA, K. ULLAS (ZFMK-MYR 09540). – 1♀, Idukki District, Pambadum Shola National Park, high altitude montane forest, hand collection, (10°08′00.3″N, 77°15′13.6″E), 1818 m, 21.XI.2019, leg. A. A. POOJA, K. S. NAFIN, K. ULLAS (ZFMK-MYR 09566). – 1♀, Pambadum Shola National Park, rain shadow region (10°07′55.4″N, 77°15′44.1″E), 1970 m, 22.XI.2019, (ZFMK-MYR 09577). – 6♀, Idukki District, Erachilpara waterfalls, Eravikulam National Park, high altitude montane forest, hand collection (10°10′28.0″N, 77°05′20.1″E), 1929 m, 13.XII.2019, leg. A. A. POOJA, J. JITHIN (ZFMK-MYR 09772). – 1 juvenile (sex undeterminable), Kollam District, Dharaphabhana chappath, Shendurney Wildlife Sanctuary, mix of evergreen and deciduous forest, Winkler extraction (8°52′40.1″N, 77°04′55.9″E), 181 m, 20.XII.2019, leg. P. P. SUDHIN, R. S. ABHIJITH (ZFMK-MYR 09808).

Family Siphonorhinidae

The phylogenetic analysis included just two of the six genera: Illacme (2 specimens) and Siphonorhinus (4 specimens). In the maximum likelihood analysis of the mitochondrial gene COI, the family Siphonorhinidae was not retrieved as monophyletic group. However, Siphonorhinus and Illacme form separate clades, with bootstrap support of 88% and 100%, respectively. Within the Siphonorhinus clade, the newly described Indian species Siphonorhinus parambikulam sp. n. is sister to the Indonesian clade, with bootstrap value of 88%. The p-distances between Siphonorhinus parambikulam sp. n. and the Indonesian Siphonorhinus are 23.0–23.3%. Within the Indonesian Siphonorhinidae clade, the p-distance between Siphonorhinus OQ708812 and OQ708813 is 0.2%, and that between these (OQ708812–13) and OQ708811 is 16.1%. The interspecific distance between the two species of Illacme is 19.9%. The p-distances between the Siphonorhinus species and Illacme are 28.4–30.9% (Fig. 8).

Family Siphonophoridae

The phylogenetic analysis includes a total of 50 sequences, of which 32 were from India, four from New Zealand, 13 from Indonesia, and one from the United States of America. Three clades of Indian Siphonophoridae could be identified in the analysis, each with bootstrap support > 96%. Clade I has bootstrap support of 99% and includes three putative lineages (lg. 1, lg. 2, lg. 3), each with bootstrap support of 100%. The p-distances within clade I are 0.0–2.1% for lg. 1, 0.0–0.8% for lg. 2, single haplotype for lg. 3, and the p-distances between these three lineages are above 7.6%. Clade II was also retrieved with three putative lineages (lg. 4, lg. 5, lg. 6), each with bootstrap support of 100%: lg. 4 has a p-distance of 1.2%, lg. 5 is a singleton, and lg. 6 is only represented by a single haplotype. The p-distances between these three lineages are 11.4–17.4%. In Clade III, three putative lineages (lg. 7, lg. 8, lg. 9) are present: lg. 7 is with a single haplotype, lg. 8 has a p-distance of 1.8%, and lg. 9 has a p-distance of 0.2–1.4%, while the p-distances between these three lineages are 10.0–18.9%. A monophyletic group containing the Siphonophoridae from New Zealand (NZ clade), with bootstrap support of 100%, was retrieved as sister to Clade I, with bootstrap support of 93%. The Indonesian specimens were retrieved as a monophyletic group (bootstrap support = 99%) and are the sister-group to the Clade I + NZ clade, with bootstrap support of 53% (Fig. 8).