Lamyctes hellyeri, Edgecombe, Gregory D. & Giribet, Gonzalo, 2003

Edgecombe, Gregory D. & Giribet, Gonzalo, 2003, A new blind Lamyctes (Chilopoda: Lithobiomorpha) from Tasmania with an analysis of molecular sequence data for the Lamyctes ­ Henicops Group, Zootaxa 152, pp. 1-23 : 6-14

Lamyctes hellyeri n. sp.

Figs. 5­37

Diagnosis: Lamyctes with body length up to 8.2 mm; tergites yellow or pale orange; ocellus lacking; 29­33 (most commonly 31) antennal articles, with a few groups of shortened articles in pairs; dental margin of maxillipede coxosternite with 2+2 teeth and stout, spinelike pseudoporodont; two or three coxal pores on each of legs 12­15; sternites of segments 13­15 fringed with setae along posterior margin, setae most numerous on sternite 14; small distal spinose projection on tibia of leg 12; leg 15 basitarsus 9­10 times longer than wide, distitarsus 11­12 times longer than wide.

Holotype: QVMAG 23:25044 ( Figs. 5, 10 ), female, Penguin, Tasmania, 41°07'04"S 146°04'40"E, R. Mesibov, 7 August 2001, garden soil.

Paratypes: Females: QVMAG 23:25045 ( Figs. 6­9 ); 23:23046 ( Figs. 11, 14­31 ); 23:23047 ( Figs. 12­13 , 32­33 ); 23:23048 ( Figs. 34­37 ), 23:23049, seven unfigured specimens; MCZ DNA 100639; all from type locality.

Etymology: For Henry Hellyer, Van Diemens Land Company surveyor and naturalist, who explored the interior of NW Tasmania in the 1820s, noting “young centipedes white as snow” in his journal.

Description: Length of body (head shield to telson) up to 8.2 mm. Leg 15 50% length of body. Colour in ethanol: head shield and maxillipede pale orange; tergites and sternites rather uniformly yellow except for pale orange segments 14­15 or all tergites pale orange with those of segments 14­15 darker; antenna yellow; legs pale yellow except for deeper yellow tarsi.

Head shield with length more than 90% its width, slightly wider than widest tergite (TT7­8). Frontal margin with strong median notch ( Fig. 11 ), lacking median furrow. Region distal to antennocellar suture desclerotised, with no trace of ocellus ( Fig. 11 ). Bor­ der of equal width posteromedially and posterolaterally; border continuous with desclerotised (“ocellar”) region. Posterior margin of head shield weakly concave. Tömösváry organ moderately large, ovate, positioned slightly closer to midwidth of cephalic pleurite than to lateral margin ( Fig. 17 ).

Antenna 33­39% length of body, 3.2­3.3 times length of head shield; basal two articles much larger than others; shortened articles in pairs include articles 3­4, 7­8, usually 10­11; articles in distal part of antenna submoniliform, mostly of about equal length and width; terminal article typically about 2.5 times length of penultimate article. Trichoid sensilla arranged in two to four imprecisely aligned whorls per article; most sensilla slanted anteriorly ( Fig. 15 ); several shorter, more slender, curved sensilla on each article ( Fig. 16 ); single digitiform thin­walled basiconic sensillum and single minute, conical thick­walled basiconic sensillum on anterior edge of articles on dorsal side of antenna ( Fig. 14 ).

Clypeus with five or seven setae at apex, unpaired median seta and two or three pairs along clypeal margin; transverse band of four setae in front of labrum includes long inner pair and short outer pair ( Fig. 12 ). Transverse seta projects from pit in sidepiece towards midpiece ( Fig. 13 ). Labral margin weakly concave where fringe of branching bristles projects a short distance beyond margin ( Fig. 13 ).

Maxillipede coxosternite subtrapezoidal ( Fig. 18 ), length (measured from anteriormost projection of teeth) about 80% width; anterolateral margins converging at 60­70º. Dental margin narrow, about 37% maximum width of coxosternite, gently curved, with 2+2 large teeth; stout, spine­like pseudoporodont just inside anterolateral corner of dental margin, separated from outer tooth by a greater distance than that separating the two teeth from each other ( Fig. 20 ); median notch with rounded apex, angle about 65º ( Fig. 19 ); rim along median notch forms small shoulder against base of inner tooth; setae of varied length on coxosternite, most concentrated on anterior part. Tarsal and pretarsal parts of tarsungulum about equal in length. Setae of similar density on inner, outer and ventral surfaces of tarsal part of tarsungulum, tibia and femur.

Mandible with four paired teeth ( Fig. 26 ). Five aciculae, each with 10­13 weakly pointed pinnules on both anterior and posterior margins ( Fig. 28 ). Fringe of branching bristles skirts aciculae; ventral bristles with fairly narrow bases, with even, dense branchings along entire length of each bristle ( Figs 27, 29 ); bristle bases flattening slightly more dorsally on fringe, with abrupt transition to rows of flat, multifurcating, scale­like bristles against second tooth; scale­like bristles arranged two­ or three­deep ( Fig. 30 ), composed of up to 26 slender branches in a single row; fringe narrowing dorsally. Grooved ridges bearing row of angular accessory denticles well developed on teeth ( Fig. 27 ); one or two rows of angular accessory denticles beside grooved ridge grade into wide band of flattened, multifurcating scales near fringe of scale­like bristles ( Fig. 30 ). Furry pad composed of long, simple and multifurcating bristles, strongly differentiated from scale­like accessory denticles on dorsalmost tooth.

First maxilla with coxal parts of coxosternum meeting along most of their length medially, separated posteriorly by small, wedge­shaped sternite. Coxal process triangular, with cluster of about four simple setae at tip, one seta just posterior to this cluster along inner margin ( Fig. 23 ). Distal article of telopod with two rows of about seven plumose setae along inner margin ( Fig. 23 ), branching along more than half of length on distal part of setae; row of about ten shorter simple setae near bases of ventral row of plumose setae ( Fig. 25 ); ventral surface of distal article with several simple setae, mostly on inner part, a few shorter setae near lateral margin.

Second maxillary sternite fused to coxa, margins distinct. Band of about six short setae across anterior part of coxa. Joint between trochanter and prefemur defined as a notch along inner margin of telopod. Inner face of tarsus with about ten plumose setae, densely branching along their distal halves ( Fig. 22 ); outer face scattered with simple setae, more numerous on distal half ( Fig. 21 ). Pretarsal claw composed of four digits of varied length and thickness ( Fig. 22 ).

Tergites smooth; all posterior angles rounded, without projections ( Fig. 5 ). All long tergites with concave posterior margins, with gradual increase in concavity posteriorly (margin of T1 gently concave; T14 moderately concave); posterior margins of short tergites subtransverse, with broadly rounded posterior angles. TT1, 3 and 5 bordered posteriorly; other long tergites bordered laterally only or with short extent of border posterolaterally; short tergites bordered laterally from T6. Tergite of intermediate segment with markedly concave posterior margin (in female). Tergite of first genital segment lightly sclerotised; telson tergite well sclerotised. Tergites with a few setae along margin and a pair anteromedially; several setae scattered on tergite of first genital segment.

Most sternites with few setae, near anterolateral and posterolateral corners, two or a few anteromedially; sternites 13­15 fringed with short setae along posterior margin, most abundant on sternite 14 ( Fig. 31 ).

Strong distal spinose projection on tibiae of legs 1­11; small, blunt projection on leg 12 ( Fig. 6 ); projections lacking on legs 13­15. Legs 12­15 with length ratios 1: 1.2: 1.4: 2.2. Leg 15 distitarsus about 90% length of basitarsus ( Fig. 9 ); basitarsus about 85% length of tibia; tibia 6­6.5 times longer than wide, basitarsus 9­10 times, distitarsus 11­12 times. Basitarsus about 72% and 80% length of distitarsus on legs 13 ( Fig. 7 ) and 14 ( Fig. 8 ), respectively. Setae on prefemur and femur of leg 15 strongly pigmented, those on tibia and tarsus slender, radiating normal to surface of leg; tibial setae on legs 1­14 similar to those of prefemur and femur, tarsal setae shorter, denser, more slender than those on more proximal segments in legs 1­13, sloping distally, e.g., on distitarsus of legs 13 and 14. Anterior and posterior accessory claws on all legs, about 40% length of main claw, gently divergent ( Fig. 36 ); accessory claws with closely­spaced linear ridges on their surface. Main claw curved along distal half, subdivided by sutures into numerous elongate scutes ( Figs. 34­ 35 ); single large pore with a small pore (gland?) opening on both lateral sides of main claw at intersection of several scutes at about midlength of the accessory claws ( Fig. 37 ); scutes proximal to pore nearly smooth, those distal to pore ornamented with fine linear ridges and grooves ( Fig. 37 ). Elongate, slender spine (sensory spur of Eason 1964, fig. 486) originating beneath base of posterior accessory claw, extending more than half length of main claw, with a short spine emanating from its base, running parallel to long spine along its upper margin.

Coxal pores all round, inner pores smaller; minimum of 2,2,2,2/2,2,2,2 in smaller specimens, maximum in largest specimen (holotype) 3,3,3,2/3,4,4,3; all other specimens with combination of two and three pores on each of legs 12­15.

Sternite of segment 15 in female with transverse posteromedian margin. Sternite of first genital segment with concave posteromedian margin; setae more abundant laterally than medially. Basal article of gonopod bearing eight to 11 setae; second article with four or five setae; third article with one or two setae ( Figs. 10 , 32 ); several long setae on first two articles. Two spurs on basal article, asymmetrical with straighter outer side, markedly tapering in distal half, with rounded tip ( Fig. 33 ). Claw simple ( Fig. 33 ).

Discussion: Lamyctes coeculus is the only other blind species in the Lamyctes ­ Henicops group. Lamyctes hellyeri and L. coeculus are most easily distinguished by the former's larger size, greater number of antennal articles, and more marked alternation in length of the antennal articles, as in the other members of Lamyctes . Throughout its range, L. coeculus has 24 articles in mature specimens, whereas L. hellyeri has 29­33. A small distal spinose projection is present on the tibia of leg 12 in L. hellyeri ( Fig. 6 ) but is absent in L. coeculus . The fringe of setae on the posterior sternites of L. hellyeri ( Fig. 31 ) is lacking in L. coeculus . Coxal pore counts are usually lower in L. coeculus (1,2,2,2 fide Brölemann 1889; 1,2,2,2 or occasionally 1,3,3,2 fide Silvestri 1909; 1,2,2,2 or 2,2,2,2, fide Negrea & Matic 1996).

Given the association between parthenogenesis and synanthropic dispersal in Lamyctes coeculus , it is plausible and even likely that the apparently parthenogenetic L. hellyeri is not a Tasmanian native. The species seems to be common in some gardens of exotic plants in the town of Penguin, but has not been collected in natural habitats (R. Mesibov, pers. comm.). Whether native or not, L. hellyeri does not conform to any previously described species of Lamyctes . The most likely suspects for a conspecific in the existing literature would be among the many species named by R. V. Chamberlin from many parts of the world. It seems unlikely that L. hellyeri is hidden among the often poorly described Chamberlin species because throughout his career Chamberlin (e.g., Chamberlin 1920, 1930, 1943; Chamberlin & Wang 1952) recognised Lamyctinus as a distinct genus. Thus, any species without ocelli (the presence of which Chamberlin sometimes did not record in his usually brief Lamyctes species descriptions) would presumably have been assigned to Lamyctinus rather than Lamyctes . The combination of presence/absence of ocelli, antennal segmentation, maxillipede dentition, distal spinose projections on the tibiae, and proportions of leg 15 distinguish L. hellyeri from all congeners listed above.

Figures

FIGURES 5 ­ 10. Lamyctes hellyeri n. sp. 5, 10, QVMAG 23: 23044, holotype female. 5, dorsal habitus, scale 1 mm; 10, ventral view of posterior segments and gonopods, scale 100 m. 6 ­ 9, QVMAG 23: 23045, female, scale 0.5 mm. 6, leg 12; 7, leg 13; 8, leg 14; 9, leg 15.

FIGURES 11 ­ 17. Lamyctes hellyeri n. sp. 11, 14 ­ 17, QVMAG 23: 23046, female. 11, anterior part of head shield and basal part of antennae, scale 100 m; 14, sensilla on dorsal side of antenna, scale 10 m; 15 ­ 16, antennal articles, dorsal side, scales 50 m; 17, cephalic pleurite with Tömösváry organ, scale 50 m. 12 ­ 13, QVMAG 23: 23047, female. 12, ventral view of clypeus and labrum, scale 100 m; 13, labral midpiece and inner parts of sidepieces, scale 30 m.

FIGURES 18 ­ 25. Lamyctes hellyeri n. sp. QVMAG 23: 23046, female. 18, ventral view of maxillipede, scale 100 m; 19 ­ 20, dental margin of maxillipede coxosternite, scales 50 m, 10 m; 21, tarsus and claw of second maxilla, scale 50 m; 22, distal part of tarsus and claw of second maxilla, scale 10 m; 23, coxal projections and telopods of first maxillae, scale 50 m; 24, first maxillae, scale 100 m; 25, plumose setae on inner margins of telopods of first maxillae, scale 10 m.

FIGURES 26 ­ 33. Lamyctes hellyeri n. sp. 26 ­ 31, QVMAG 23: 23046, female. 26 ­ 27, gnathal edge of mandible and detail of ventral part, scales 10 m; 28, aciculae, scale 10 m; 29, 30, fringe of branching bristles, on successively more dorsal part of mandible, scales 10 m; 31, sternite of segment 15 and posterior margin of sternite 14, scale 100 m. 32 ­ 33, QVMAG 23: 23047, female, gonopod and detail of spurs and claw, scales 50 m, 10 m.

FIGURES 34 ­ 37. Lamyctes hellyeri n. sp. QVMAG 23: 23048, female, pretarsus of leg 14, scales 10 m. 34 ­ 36, anterior, posterior, and ventral views; 37, detail of lateral pore and ornament on scutes of main claw.