Lyrognathus crotalus Pocock 1895
Creators: name: West, Rick C.
name: Nunn, Steven C.
Publisher: name: Zenodo
Year: 2010
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Theraphosidae
Lyrognathus
Lyrognathus crotalus

description: Lyrognathus crotalus Pocock 1895
(Figs 1–12, 114)
Lyrognathus crotalus Pocock 1895: 175; Platnick, 2009.
Lyrognathus pugnax Pocock 1900: 203; Platnick, 2009. New synonymy.
Types: Lyrognathus crotalus Pocock 1895, female holotype, 1854.16, Assam State, northeastern India, NHM.—images and illustrations (R. Raven, A. Smith, V. von Wirth, pers. comm.).
Lyrognathus pugnax Pocock 1900, female holotype, 1895.1.28.1, Shillong (25°34' N, 91°53' E), Meghalaya State, northeastern India, NHM.—images, illustrations (A. Smith, V. von Wirth, pers. comm.).
Other material: Lyrognathus crotalus Pocock 1895, female topotype, 0 9.10.7.36, North Khasi Hills (25°34' N, 91°37' E), Meghalaya State, northeastern India, NHM.–illustrations (A. Smith, pers. comm.); male, 0 0 0 0 0 641, North Khasi Hills, Meghalaya State, northeastern India, ZMUC.—illustrations (A. Smith, pers.
comm.); 1 male, 1853.54-11, Shillong, Meghalaya State, northeastern India, ZSL.—illustrations (A. Smith, pers. comm.)(new det.).
Diagnosis (females): Differs from other Lyrognathus species in the intercheliceral spines, not pegs (Fig. 10, except L. saltator) and unilobular spermathecae (Fig. 6). Differs from L. saltator in having only 5 apical spines on metatarsi IV and highly incrassate tibia IV (Fig. 8). Differs from L. achilles sp. nov., L. fuscus sp. nov., L. lessunda sp. nov. and L. robustus in having unilobular spermathecae, presence of intercheliceral spiniform setae (not pegs) and absence of retrolateral basomedial cheliceral spines. Leg formula length IV, I, II = III (41, 32, 27, 27) and width IV, III, I, II. Leg RF ~78.05.
Description: Female holotype with body length: 26.4.
Color (in life, Fig. 1): entirely dark grey to black.
Carapace (Fig. 1): length 13.5, width 10.0. Fovea wide, procurved, deep, equal in width to OT.
Eyes: AME, ALE, PLE, PME. Anterior row transverse, posterior row recurved. OT highest posteriorly behind AME, sloping gradually anteriorly.
Chelicerae (left, Figs 9, 10): ectal lyrate region a series of strikers (>65) in 7 horizontal rows (Fig. 9). Strongest and longest strikers on lowest rows. Each striker needle-form. Teeth, 10,>50 basomesal teeth. Intercheliceral spines (>8) in tight cluster on basodorsal surface (Fig. 10). Retrolateral surface lacks basomedial spine cluster.
Maxillae (Fig. 7): prolaterally plano-convex, anterior lobe well pronounced, many cuspules (> 120) on inner basoventral surface. Lyra (Fig. 7): bacilliform rods (>155) form dense, ovoid patch on prolateral surface, lowest row with>26 bacillae, longest rods medially in lowest row. Rods distally paddle-shaped with medium to long shafts, largest rods lacking distal blades. At widest point, lyrate patch 11 rows deep with smallest rods dorsally. Posterior end of patch truncate but rounded, anterior end rounded. Immediately above maxillary suture>11 elongated spines on anterior margin, rows disordered. Labium: many small cuspules (>450) along anterior 1/4 surface.
Sternum: saddle-form. Posteriorly between left and right coxae IV, border highly acuminate, lateral points slightly acuminate. Sigilla: 3 pairs (not including labio-sternal sigilla), posterior, large in size. Ovular, 1.5 of their length apart, 1.0–1.2 of their length from margin. Median pair, 1/2 size of posterior, similar in form and 0.6–0.7 of their length from margin. Anterior pair very small, somewhat obscured and border margin. Labiosternal sigilla largest of all, 1.2 times size of PSS.
Legs (Figs. 3, 4, 8): formula (length); IV, I, II, III: (width); IV, III, I, II. Leg RF ~78.05. Leg lengths: palp: 19, I: 32, II: 27, III: 27, IV: 41. Tib. IV with strong retrolateral villous setal fringe, proximally to distally uniform–entire (Fig. 8).
Scopulae: met. I–IV undivided, tar. I–II. undivided, tar. III partially divided proximally (by one row of sparse setae>5, nonexistent in distal 1/2), tar. IV divided by 2–3 rows of setae. Met. I–IV, covers full length ventrally.
Coxae: some small black thorns prolatero-dorsally, no thorns retrolaterally on I–IV. Coxae easily seen dorsally. Cox. I longest, ca. 1.3 times length of II. IV widest, as long as III, basally rectangular with rounded corners. Coxae with small ventral thorns prolaterally on I–IV. I–III ventrally with numerous long thick blunt setae proximally, pallid. No short black setae. IV with mixture of long thick blunt setae entirely, pallid intermixed with shorter thin pallid setae. Ventral surface of coxae I–IV gently sloping anteriorly. Retrolateral setation: I–III with median narrow light brush, IV entirely covered in short thin pallid setae. I–IV retrolaterally lack ventral ledge.
Trichobothria: on all tarsi basal filiform field slightly wider than clavate field, merges evenly. Clavates on tar. I in distal 1/2 (very dark), long filiforms only in basal 2/3, shorter filiforms intermixed with clavates distally. Clavate extent on tar. II–IV cf. I, in distal 1/2. Shorter filiforms for length. Short epitrichobothrial field on I shorter than clavates, increasing in length proximally.
Spines: met. I with 1 DV, met. II with 1 DV, 1 DPV, 1 DRV, met. III with 2 DV, 1DPV, 1 DRV, 1 DD, 1 DPL and met. IV with 2 DV, 1DPV, 1 DRV, 1 DPD.
Claws: unarmed claws on all legs and palps. Reduced third claw absent on leg IV.
Abdomen (Fig. 3): ovular, elongated, yellow brown in alcohol, black in life.
Genitalia (Fig. 6): spermathecae paired but not fused, unilobular apically, each lobe with mild apical rounded expansions, ovular in form, heavily sclerotized gradually transition to weakly sclerotized shafts proximally. In L. crotalus topotype (09.10.7.36, Fig. 6), lobes bend slightly laterally and medially, in L. pugnax holotype (1895.1.28.1), lobes lack bend.
Distribution and natural history (Figs 11, 12, 114): Known only from the type locality of Assam State and from Shillong, Meghalaya State with confirmed reports also throughout Meghalaya State to the south and west (S. Rafn, M. Siliwal and J-M. Verdez, pers. comm.). Assam State is located directly south of the Eastern Himalayas and shares borders with the countries of Bhutan and Bangladesh. To the south of Assam State is Meghalaya State. About one-third of the small state of Meghalaya is heavily forested, the Sanskrit name itself translates in English to “The Abode of Clouds”. The spiders were widely distributed but common in partially shaded laterite roadside or trail embankments in open areas of bamboo and evergreen deciduous forest of the East Garo Hills, Meghalaya State, India at elevations of 300–550 meters.
L. crotalus construct simple flare-mouthed tubular burrows, utilizing surrounding organic debris or vegetation around the mouth, on almost vertical embankments (Figs 11, 12). Adult female burrows were Jshaped and entirely lined with silk, terminating in an enlarged chamber about 30–50 cm deep. An ultimate male was found in a burrow in October, females were observed with egg sacs in February and young instars were observed in mid-April to early May (S. Rafn and J-M. Verdez, pers. comm.).
Remarks: When Pocock (1895) described L. crotalus, he had putatively examined two specimens he identified belonging to that species, sent to the NHM in 1854 (Smith 1988). He discussed one (1854.16) as the ‘type’ in 1895, but neglected to mention the other (09.10.7.36). Although Pocock had putatively examined both specimens prior to his publication, the later specimen can only be considered a "topotype", i.e., of no formal nomenclatural status.
Siliwal (pers. comm.) noted significant variation within Lyrognathus specimens collected in and around the L. crotalus type locality: Guwahati City (26°11' N, 91°45' E) and Nameri National Park (26°57' N, 92°45' E), Sonitpur District, Assam State, Northeast India. Clypeus widths seem to vary in conspecifics, as does the partial division of tarsi III scopula previously thought diagnostic of L. crotalus. In addition, the types only vary in size (L. pugnax is slightly larger), the tarsi III scopula division and slight spermathecal variation. The spermathecal variation is minimal (in the L. crotalus topotype female 0 9.10.7.36, the spermathecae bend slightly laterally and medially, in L. pugnax holotype female, they do not), particularly considering both specimens were dry stored at the NHM for over 30 years before being placed into wet preservative and may therefore be distorted.
S. Rafn (pers. comm.) reported only spiders conspecific with L. crotalus in Shillong district (type locality for L. pugnax) which show a blend between partially divided and undivided tarsi III scopula, but no distinct division between specimens collected. We consider that, as L. pugnax is based only one (type) specimen with a reduced clypeus and minimal variation of tarsi III scopula division in comparison to sympatric L. crotalus types, that L. pugnax is clearly a large L. crotalus with undivided tarsi III scopula and reduced clypeus. Prior to 1903, tarsal scopula division was considered of great taxonomic use (incorrectly considering juveniles: see Guadanucci 2005), possibly explaining Pocock actions at that time. We, therefore, consider L. crotalus Pocock 1895 a senior synonym of L. pugnax Pocock 1900.
description: Published as part of West, Rick C. & Nunn, Steven C., 2010, A taxonomic revision of the tarantula spider genus Lyrognathus Pocock 1895 (Araneae, Theraphosidae), with notes on the Selenocosmiinae, pp. 1-43 in Zootaxa 2362 on pages 6-11, DOI: 10.5281/zenodo.275727