Damarchus pylorus Schwendinger & Hongpadharakiree 2023, sp. nov.
Creators: name: Schwendinger, Peter J.
name: Hongpadharakiree, Komsan
Publisher: name: Zenodo
Year: 2023
Subjects: Biodiversity
Taxonomy
Animalia
Arthropoda
Arachnida
Araneae
Bemmeridae
Damarchus
Damarchus pylorus

description: Damarchus pylorus sp. nov.
Figures 1–4, 5A–B, 6
Holotype. MHNG-ARTO-0034004; male (matured 9.III.2016); Thailand, Uthai Thani Province, Lan Sak District, near Hub Pa Tad, 15°22’46”N, 99°37’44”E, 110 m (sample CT-13-14/03); 18.XII.2013; leg. P.J. Schwendinger.
Paratypes. MHNG-ARTO-0034005-0034010; 6 males (matured 18.II.2016; 27.III.2016; 25.V.2016; III.– IV.2017; hatched 19.VII.2017, matured 12.IV.2021; hatched 19.VII.2017, matured 24.IV.2021); same data as for holotype. MHNG-ARTO-0034012-0034013; 2 females (allotype MHNG-ARTO-0034012; other hatched 19.VII.2017); same data as for holotype. THNHM; 1 male (hatched 19.VII.2017, matured 1.V.2020) and 1 female; same data as for holotype.
Etymology. The Latinized form of the ancient Greek noun “pyloros” (= gate keeper) refers to the idiopid trapdoor spider Idiops pylorus Schwendinger, 1991 which employs a very similar burrow plugging mechanism and occurs in the same country.
Diagnosis. Different from all other known Damarchus species, expect for D. lanna sp. nov., by males possessing a para-embolic apophysis (Figs 1G–I, 2C–F), and females having receptacles composed of a strongly sclerotized base and an unsclerotized head situated on the ventral surface of a large genital atrium (Fig. 4); both sexes with a more or less strongly reduced unpaired claw on tarsi I–III (Fig. 3K). Distinguished from the similar D. lanna sp. nov. by males having a long, claw-like para-embolic apophysis on the lower (posterior) side of the palpal organ (developed as a small triangular lamina on the prolateral side of the palpal organ in D. lanna sp. nov.; Figs 1G–I, 2C–F cf. Fig. 7M–R), and by females having patellae I–III mostly longer than metatarsi I–III (patellae I–II mostly longer than metatarsi I–II in D. lanna sp. nov.) and possessing a short wreath-shaped sclerotized receptacular base and a very short, bubble-shaped unsclerotized receptacular head (receptacles much longer, with conical base and digitiform or club-shaped head in D. lanna sp. nov.; Fig. 4 cf. Fig. 10).
Description of male holotype: Colour in alcohol (much darker in living males, see Fig. 1A–B): Carapace with dark brown pattern (including a median stripe running from eye mound to fovea) on pars cephalica; pars thoracica mostly brown, with irregular dark radiating bands on coxal elevations (anterior ones longer than posterior ones); eye mound black, except for dark brown posterior area between and around PME (Fig. 1D). Chelicerae light brown proximally, increasingly darker towards apex; claws very dark brown. Palps with trochanter and femur dorsally slightly darker than other articles. Legs mostly brown, dorsal side of metatarsi and tarsi I–II dark brown. Ventral side of prosoma and legs light brown. Opisthosoma dorsally grey, laterally and ventrally (including all spinnerets and anal tubercle) cream-coloured (Fig. 1F); genital area and booklung covers very light brown.
Morphology and measurements: Body 13.87 long. Carapace 5.10 long, 3.64 wide, its anterior margin slightly recurved, its posterior margin invaginated (Fig. 1D); pars cephalica indistinctly arched, its slope continuous with that of pars thoracica (Fig. 1C); few short hairs on pars cephalica, longer and stronger ones on lateral margins and in posterior part of pars thoracica, some of the latter slightly wavy; no hairs close to fovea. Fovea widely U-shaped, 0.65 wide, occupying 18% of carapace width at that point (Fig. 1D). Eight eyes on low but distinct mound; eye group 0.50 long, anterior eye row straight, 1.02 wide, posterior eye row slightly recurved, 0.99 wide. MOQ 0.46 long, 0.58 wide anteriorly, 0.69 posteriorly. Eye diameters: AME 0.25, ALE 0.27, PME 0.20, PLE 0.20. Proximal article of chelicera 2.05 long, fairly strong, without intercheliceral tumescence; ventral groove with 7/8 teeth arranged in a medially transposed row (see Fig. 3I for female) on promargin and a short row of 9/10 tiny light-coloured medioproximal denticles; rastellum sessile (not raised on process), composed of 3–4 strong short spines and several weaker and more pointed spines above fang articulation. Palpal coxa 1.75 long, 0.97 wide; anterior lobe short, without serrula; with over 30 cuspules in prolateral-proximal corner. Labium 0.55 long, 0.91 wide, with three cuspules. Sternum 2.86 long, 1.49 wide; labiosternal suture quite long and deep at posterior margin, fused with anterior pair of sigilla; three pairs of free sigilla, anterior pair smallest and closest to sternal margin, median pair equally small but further away from margin, posterior sigilla ellipsoid, about two times longer than wide, even more remote from margin, medially separated from each other by distinctly more than their length (Fig. 1E).
Palp (Figs 1G–I, 2C–F) 5.39 long (1.95 + 1.07 + 1.56 + 0.81). No spines. Tibia ventrally with several long strong bristles; retrolaterally with a distinct distal field of spinules continuing into a median field of increasingly longer pine-needle-shaped bristles (Fig. 1H–I). Tarsus short, without spines, strong bristles or scopula, distally with three lobes, a very short median one and two longer lateral ones (Fig. 1G–H). Trichobothria: 6+ 6 in two rows on tibia, six in an irregular row on tarsus. Palpal organ quite short and robust, with wide transition between bulbous proximal part and embolus; apex of embolus abruptly tapering to a spiniform, slightly curved tip; lower (proximal) surface of palpal organ with a distinct keel formed of several laminae in the shape of shark teeth or fish scales, the distalmost of them elongated to a strong, distad-directed, claw-like para-embolic apophysis; apex of embolus and para-embolic apophysis together forming a two-pronged fork (Figs 1G, I, 2C–F).
Legs 3214; femora I–II slightly more compressed than femora III–IV. Leg I 15.63 long (4.16 + 2.47 + 3.90 + 2.92 + 2.18); leg II 13.15 long (3.57 + 2.11 + 3.05 + 2.60 + 1.82); leg III 10.65 long (2.79 + 1.69 + 1.75 + 2.73 + 1.69); leg IV 15.95 long (4.19 + 2.21 + 4.03 + 3.77 + 1.75). All patellae shorter than corresponding metatarsi. Leg tarsi not pseudosegmented and without spines, with a light ventral scopula; tarsi I–II slightly spindle-shaped, tarsi III–IV cylindrical. Scopulae covering entire ventral side of all tarsi, plus distal two-fifths of metatarsus I and distal third of metatarsus II. Metatarsal preening combs absent on legs I–II, indistinctly expressed as a single small group of long thin bristles on legs III–IV. Leg I: metatarsus slightly bent at its base, proximal to midpoint with a knob-shaped proventral process densely covered with numerous cuspules (Fig. 1J–L); tibia cylindrical, not incrassate but thicker than metatarsus I, with a fairly long digitiform proventral coupling spur tipped by a relatively short (clearly shorter than spur) arrowhead-shaped megaspine (Figs 1B, J–L, 2A–B).
Spines: Leg I: patella, 0; tibia p2/3, v4 (including megaspine on coupling spur); metatarsus p2, r1, v4. Leg II: patella, 0; tibia v4 (proventral-distal one weakest); metatarsus p2, r1, v4 (proximal pair weakest). Leg III: patella p3; tibia d3, r1/2, v6 (two proventral weakest); metatarsus d8, p2, r1, v3/4. Leg IV: patella, 0; tibia d1, v6/7 (posterior pair weakest); metatarsus d3, r1, v4. Trichobothria: 7–8 each in two rows on tibiae, 8–12 in a single irregular row on metatarsi, 8–10 in a single zig-zag row on tarsi. Paired tarsal claws with 9–11 teeth in a S-shaped row on anterior legs, 6–7 on posterior legs; unpaired claw indiscernible on legs I–III, a tiny bare claw visible on leg IV (Fig. 1M).
Opisthosoma somewhat cylindrical in shape, relatively long and with lateral margins almost parallel to each other (see Fig. 1A for male paratype), 6.14 long, 3.44 wide; densely covered with dark hairs, dorsal ones longer and stronger than lateral and ventral ones. PMS 0.62 long, separated from each other by 0.19 (equal to their width); PLS 3.04 long (proximal article 1.23, median article 0.84, distal article 0.97), separated from each other by 0.58 (slightly more than diameter of proximal article; Fig. 1F).
Description of female allotype. Colour in alcohol (for colour of two living females, including allotype, see Fig. 3A–B): Generally lighter than in males. Carapace with contrast between mostly dark brown pars cephalica and light brown pars thoracica more pronounced than in male (Fig. 3D cf. Fig. 1D). Chelicerae (including fang) darker than in male, posterior legs slightly lighter, sternum, labium and palpal coxae slightly more reddish. Colour of opisthosoma obscured by cuticle being partly detached from underlying tissue, in other females lighter than in males; genital region light orange-brown (see Fig. 3F for female paratype).
Morphology and measurements: Body 18.31 long. Carapace 5.65 long, 3.83 wide, its anterior margin slightly recurved, its posterior margin widely invaginated (Fig. 3D); pars cephalica in profile more strongly arched than in male, with a distinct small pit-like lateral depression on each side at transition between pars cephalica and pars thoracica (Fig. 3C); hairs in median row behind eye mound distinctly longer and stronger than in male, hairs on pars thoracica distinctly weaker (Fig. 3D cf. Fig. 1D). Fovea widely U-shaped, 0.84 wide, occupying 23% of carapace width at that point. Eye mound distinct; eye group 0.60 long, anterior eye row essentially straight, 1.15 wide, posterior eye row slightly recurved, 1.10 wide. MOQ 0.50 long, 0.61 wide anteriorly, 0.79 posteriorly. Eye diameters: AME 0.25, ALE 0.30, PME 0.24, PLE 0.24. Proximal article of chelicera 2.69 long, stronger than in male, without intercheliceral tumescence; ventral groove with seven teeth arranged in a medially transposed row on promargin (Fig. 3I) and with a short row of ten tiny black medioproximal denticles; rastellum sessile, composed of about ten strong short spines in 2–3 rows and several similarly thick but more pointed spines above fang articulation. Palpal coxa 2.21 long, 1.30 wide; no serrula; with over 40 cuspules in prolateral-proximal corner. Labium 0.58 long, 1.10 wide, with three cuspules. Sternum 3.38 long, 2.47 wide; posterior sigilla more elongate than in male, almost four times longer than wide, medially separated from each other by slightly more than their length (Fig. 3E).
Palp 6.69 long (2.21 + 1.30 + 1.56 + 1.62). Spines: patella p2, tibia p4, v6, tarsus v1/2. Tibia dorsally with a distinct subdistal pseudosegmentation, i.e., a pallid transverse band (Fig. 3J), a character found in all bemmerids and nemesiids examined but often indistinctly developed. Tarsus with ventral spines and with scopula covering entire length of article prolaterally and proventrally but only its distal half retrolaterally and retroventrally; palpal claw with nine teeth in proventral row. Trichobothria: 7+ 7 in two rows on tibia, seven in an irregular row on tarsus.
Legs 3241; all articles (especially femora) of legs I–II more distinctly compressed than in male; leg I without modifications. Leg I 12.77 long (3.64 + 2.34 + 2.92 + 2.18 + 1.69); leg II 10.71 long (3.05 + 2.11 + 2.27 + 1.92 + 1.36); leg III 8.18 long (2.21 + 1.75 + 1.17 + 1.72 + 1.33); leg IV 12.49 long (3.44 + 2.27 + 3.05 + 2.53 + 1.20). Patellae I–III longer than metatarsi I–III; patella lV shorter than metatarsus IV. Scopulae covering entire ventral side of leg tarsi I–II, plus distal four-fifths of metatarsus I and distal third of metatarsus II; no scopulae on legs III–IV. Metatarsal preening combs absent on leg I; on metatarsus II only a proventral comb composed of 2/3 bristles (Fig. 3N); on metatarsus III a proventral and a retroventral comb of four bristles; on metatarsus IV a weak proventral and a strong retroventral comb of three and 5/6 bristles, respectively (Fig. 3M, O–P).
Spines: Leg I: patella p1; tibia p4/5, v5; metatarsus p1/2, v5/6. Leg II: patella p3; tibia p3, v3; metatarsus p2/3, v6/7. Leg III: patella p3; tibia p1/2, r2, v1; metatarsus d7/8, p2, v4. Leg IV: patella, 0; tibia v1; metatarsus d3, v4. Dense patches of spinules (weaker than in females of D. lanna sp. nov., stronger than in D. dao sp. nov.) dorsally on patella III and patella IV (on the latter spinules becoming thinner in distal half), divided by an oblique glabrous band, plus a dorsodistal group of strong spinules on femur IV. Paired tarsal claws with 8+8 teeth in two rows on legs I–II, 2–4 on legs III–IV; unpaired claw indiscernible on legs I–II, a tiny bare claw present on leg III (Fig. 3K) and a small bare claw on leg IV (Fig. 3L–M). Trichobothria: 7–10 each in two rows on tibiae, eight in a single irregular row on metatarsi, eight in a single zig-zag row on tarsi.
Opisthosoma relatively long and somewhat cylindrical (Fig. 3B, see also Fig. 3A for another female), 9.48 long, 5.58 wide, with hair cover as in male. PMS 0.72 long, separated from each other by 0.23 (slightly less than their diameter), PLS 3.01 long (proximal article 1.23, median article 0.84, distal article 0.94), separated by 0.62 (slightly more than diameter of proximal article) (Fig. 3G–H).
Vulva (Fig. 4A): Genital atrium wide and long, its anterior margin slightly invaginated. A single pair of widely separated, very short receptacles situated on ventral side of atrium, in its distal half. Each receptacle composed of a short, wide, wreath-shaped, strongly sclerotized base and of a short, bubble-shaped, unsclerotized head. A small sclerotized spot present on both sides of genital atrium, retrolateral of each receptacle. For other sclerotisations in the vulvae see following paragraph.
Variation. Carapace lengths in males (n = 8) range 4.19–5.47, in females (n = 3) 4.81–5.68; carapace widths in males range 3.07–4.15, in females 3.23–4.81. The shape of the posterior margin of the carapace in males ranges from straight to slightly and widely invaginated and to moderately and narrowly invaginated. The lateral depressions between the cephalic and thoracic parts of the carapace of females are pit-like in the allotype (Fig. 3C), more elongate in the two paratypes. All females and most males have three short prolateral spines on patella III; the largest male has four spines (the most proximal one rather weak) on the right side and three on the left side. The three females examined have patellae I–II on both sides of the body longer than metatarsi I–II, and patella III either slightly longer than or as long as metatarsus III; patella IV is always clearly shorter than metatarsus IV (see also Discussion). All females have a distinct subdistal pseudosegmentation on their palpal tibia (Fig. 3J); in females of the other two new species described here this is less pronounced. In all males metatarsal preening combs are absent on legs I–II, present on legs III–IV (in some specimens on one side less clearly developed than on the other side). In all females the preening combs are absent on metatarsus I, present and more or less distinct on metatarsi II–IV. In all males the unpaired tarsal claw is absent on legs I–III, present but tiny on leg IV. In two females the unpaired claw is absent or indiscernible on tarsi I–II, in one paratype a tiny unpaired claw is present on the right tarsus I; in two female paratypes that claw is tiny on tarsus III (Fig. 3K); in all three females examined it is small and well-discernible on tarsus IV (Fig. 3L–M). The number of labial cuspules in males is 2–7, in females 3–5. The pigmented area below (posterior of) each receptacle of the vulva of the allotype is an untypical, random sclerotisation (Fig. 4A) which can often be found in the vulvae of large and old mygalomorph and liphistiid spider females. This clearly is not part of the sclerotized receptacular base, and it is not present in the other two females examined (Fig. 4B–E). The smaller, sclerotized lateral spots present on both sides of the genital atrium (indicated by arrows in Fig. 4A–D) are present in all conspecific females examined and therefore they are a typical part of the vulva of D. pylorus sp. nov.
Relationships. Due to its relatively small, submarginal and medially not confluent posterior sternal sigilla, as well as the presence of labial cuspules and metatarsal preening combs on legs III–IV and the absence of a scopula on tarsus IV, the new species currently fits well in the genus Damarchus. However, the combination of a para-embolic apophysis and receptacula seminis composed of a wide, strongly sclerotized base and an unsclerotized head make D. pylorus sp. nov. and D. lanna sp. nov. clearly stand out among Asian Bemmeridae and Nemesiidae. See also Discussion.
Distribution. The new species is known only from its type locality at the western edge of the great plain of central Thailand.
Biology. Habitat: The spiders examined were collected from flat to moderately sloping ground in a dry secondary forest at the base of a limestone hill.
Burrow: As typical for Damarchus species, the burrow is composed of a main shaft from which branches a blind side shaft. The main shaft is about 10–12 cm long and almost vertical. A few centimetres above the bottom of the main shaft a side shaft branches upward at an acute angle without reaching the surface. In there, the spider hides when something intrudes into the burrow (Fig. 5A–B). There is, however, a modification to this burrow that makes D. pylorus sp. nov. biologically unique among Asian Bemmeridae and Nemesiidae, and that only has parallels in the pycnothelid Stanwellia nebulosa Rainbow & Pulleine, 1918 from Australia and in the idiopid Idiops pylorus from Thailand. At the entrance of the side shaft, a compact soil pellet (Figs 5A–B, 6), moulded by the spider from soil particles and saliva, rests in a chamber in the floor. The entire upper, slightly concave and rather wide surface of the pellet (which constitutes the lower floor behind the entrance to the side shaft) is firmly attached to a collar of quite tough silk that lines the zone behind the side shaft entrance (Fig. 5A). Behind the soil pellet, the silk collar connects with the lining of the side shaft and that point serves as a hinge at which the pellet can be folded up and down. The lower part of the pellet is first about as wide as the diameter of the side shaft and then narrows to a coarsely dentate keel (Fig. 6). To plug the side shaft entrance, the spider pulls the soil pellet from its tightly fitting resting chamber upward into the interior and thus blocks access to the side shaft (Fig. 5B). The largest soil pellet built in captivity is 0.80 cm long, 0.55 cm wide and 0.80 cm deep. As reported for the spindle-shaped soil pellet of Nemesia fagei Frade & Bacelar, 1931 (see Bacelar, 1937: 1576), the devices made in captivity are not as elaborate as the ones made in nature. The soil plugs of D. pylorus sp. nov. found in the field (not photographed and not collected) have more distinctly outlined teeth forming the keel, plus a small round and flat area in front of the teeth (not discernible in soil pellets built in captivity).
Phenology: Males collected in the field in mid-December matured in captivity in February to May of the following year and in late March or early April of the year after. Second generation males that hatched in captivity in late July 2017 became mature in May 2020 and in April 2021, almost three years (one male) and almost four years (two males) later. A female that mated in captivity in late April 2017 had 44 spiderlings hatching exactly three months later. They stayed in the burrow of the mother for another 1.5 months.
description: Published as part of Schwendinger, Peter J. & Hongpadharakiree, Komsan, 2023, Three new and exceptional Damarchus species from Thailand (Araneae: Bemmeridae), pp. 481-508 in Zootaxa 5336 (4) on pages 482-489, DOI: 10.11646/zootaxa.5336.4.2, http://zenodo.org/record/8282032