Spinotarsus fortehamatus, Enghoff, 2018

Enghoff, Henrik, 2018, A mountain of millipedes VI. New records, new species, a new genus and a general discussion of Odontopygidae from the Udzungwa Mts, Tanzania (Diplopoda, Spirostreptida, Odontopygidae), European Journal of Taxonomy 394, pp. 1-29 : 20-23

Spinotarsus fortehamatus sp. nov.

urn:lsid:zoobank.org:act:B9ACE322-7B35-4879-9DC4-B5F08E666121

Fig. 9

Diagnosis

A species of Spinotarsus characterized by the very large, regularly curving lateral metaplical spine, in combination with the presence of a spine at the base of the solenomerite and a row of denticles on the terminal part of the telomere.

Etymology

The name is a composite Latin adjective, meaning “with a strong hook” and referring to the strong lateral, hook-shaped spine of the gonopod coxa.

Material studied (total: 1 ♂)

Holotype

TANZANIA: ♂, Morogoro Region, Udzungwa Mountains National Park, Sanje Kati camp and plot , 07°45′47.6′′ S, 36°53′10.4′′ E, 850 m a.s.l., 7 Feb. 2014, J. Malumbres-Olarte leg. ( ZMUC).

Description

Male

SIZE. Length ca 6 cm, diameter 5.0 mm, 59 podous rings, no apodous rings in front of telson.

COLOUR. Apparently quite well-preserved after 3 years in alcohol: head below antennae yellowish; head above antennae blackish, parietal and interocular furrows contrastingly yellow; antennae brown, collum blackish with lighter margins; body rings light grey, metazona with black sputtering, posterior ⅓ of metazona amber; a yellow dorsal longitudinal stripe on posterior ¼ of body; legs yellow; preanal ring grey, dorsally yellow; anal valves blackish with lighter margin; subanal scale yellow.

HEAD. Parietal and interocular furrows present; 7 supralabral setae. Antennae reaching to ring 6 when folded back. Eyes reaching to median tangent to antennal socket, each with nine rows of ommatidia, 7 horizontal rows, and a total of ca 38 ommatidia each.

COLLUM. Lateral lobes subrectangular, each with two furrows.

BODY RINGS. Unvaulted; metazona and posterior part of prosoma with numerous short very fine longitudinal furrows; ozopores ca ⅓ of metazona length behind straight suture.

OZOPORES. Missing from rings 31 (left side), 47 (both sides), 56 (right), 58 (left) and 59 (both).

ANAL VALVES. Each with a stout dorsal spine and a tiny ventral knob-like spine; mesal margin slightly raised, setiferous tubercles indistinct, not on ravelins.

LIMBUS ( Fig. 9G ). With long (more than twice as long as broad), pointed lobes.

GONOPOD COXA ( Fig. 9F ). Slightly more than twice as long as broad. Proplica ending in small proplical lobe (ppl). Metaplica longer than proplica, apically forming a “cucullus” (cu). Mesal margin of metaplica with a curved lamellar process (mlp) just distal to exit point of telopodite (“arculus”). Metaplica laterally with a very large spine (msp) curving distad in a latero-posterior plane. Proplical lobe, lateral metaplical spine and a stripe parallel to lateral metaplical margin from spine to tip of cucullus black (not visible on SEM image).

GONOPOD TELOPODITE ( Fig. 9A–E ). Arculus 90°. A very long post-torsal spine (pts) making almost 1½ turns around torsotope (tt) ( Fig. 9C–D ). Solenomere (slm) as long as telomere, thin, simple, without outgrowths, apically with oblique-longitudinal fluting.A long spine (ps) originating at base of solenomere and projecting at right angles to it ( Fig. 9A ). Telomere (tm) curving in an almost complete circle, basally with large spinose lamella (bla) projecting into space delimited by telomere curvature, followed by two smooth lamellae (el1, el2) projecting from outside of curvature ( Fig. 9A ); distal part of telomere slender, longitudinally folded, one margin with a series of black denticles (td, colour not visible on SEM image; Fig. 9D ).

Female

Unknown.

Remarks

The basal spinose lamella of the telomere (bla) is a key character for Spinotarsus (the name actually refers to the lamella – the telomere was formerly referred to as the tarsus). Many species of Spinotarsus possess an additional apomorphy, namely a darkly sclerotized ridge on the posterior surface of the telomere, but such a ridge is absent in S. fortehamatus sp. nov. In the most recent key to species of Spinotarsus ( Kraus 1966: 110–113), the new species keys out without problems to couplet 60, as follows (couplet texts translated from German and adapted to current terminology, characters of S. fortehamatus sp. nov. in bold): couplet 1: Gonopodal metaplica with one or several dark sclerotized lateral spines which stand clearly out in strict oral view → couplet 38: One or more spine(s) (“Postfemoraldorn”) at base of solenomere present → couplet 59: One spine at base of solenomere → couplet 60. “Couplet” 60 is, however, deficient in the key, which can be seen by comparison with the older key by Kraus (1960: 122, “couplet” 42). The “couplet” in question is actually a “triplet”, but the third option is lacking in the 1966 key. In translation, “triplet” 60 in Kraus (1966) should run:

60. Metaplica distally coarsely serrate ................................................................................... denticulatus

– Metaplica distally ending in a slender, spine-like process with a blackened tip; this process inserting apico-mesally...................................................................................................................................61

– Tip of metaplica different ..............................................................................................................65

Continuing in couplet 65, the new species fulfils the second alternative: Lateral metaplical spine directed ± apicad → couplet 68: Metaplica apically without a process or just with a delicate hyaline, spoonshaped appendage → couplet 81: Terminal lamella of telomere with spiny margin and 1 –2 longitudinal row s of denticles on the internal surface (→ couplet 82) vs Terminal lamella of telomere completely smooth, internal surface of telomere without obvious spine rows (→ couplet 84). The new species has a smooth margin of the terminal part of the telomere, but it also has a very obvious row of spines on the internal surface of the telomere. It thus fits one criterium of each alternative. In addition to its unique combination of key characters, it also differs from congeners in the shape of the lateral metaplical spine: none of the almost one hundred described species of Spinotarsus have an equally large, equally smoothly curved lateral metaplical spine. Those which come closest in this character, i.e., S. demotus Kraus, 1966 ( Angola) , S. kruegeri Kraus, 1966 ( South Africa), S. lanceolatus Kraus, 1966 ( Zimbabwe) and S. pusillus Kraus, 1966 ( South Africa), differ clearly in other characters.

The lack of ozopores on one or both sides of certain body rings is a highly unusual trait. In juliformian millipedes, ozopores are normally present in an uninterrupted series usually starting on body ring 6, rarely on ring 5, exceptionally on ring 3, and continuing to include the last podous ring. Up to now, the only exception to this rule is constituted by two species of the family Mongoliulidae , in which ozoporeless body rings occur in a regular pattern along the body ( Enghoff et al. 2017).

Figures

Fig. 9. Spinotarsus fortehamatus sp. nov., holotype. A–E. Right gonopod telopodite.A. Posterior view. B. Basal lamella of telomere, enlarged. C. Anterior view. D. Posterior-mesal view. E. Distal part of solenomere. F. Right gonopod coxa, posterior and slightly mesal view. G. Limbus. Abbreviations: bla = basal lamella of telomere; cu = cucullus; el1, el2 = smooth telomeral lamellae; mlp = metaplical lamellar process; msp= metaplical spine-like process; ppl = proplical lobe; ps = proximal solenomeral spine;pts = post-torsal spine; slm = solenomere; td = telomeral denticles; tm = telomere; tt = torsotope. Scale bars:A, C–D,F = 0.2 mm; B, E = 0.1 mm; G = 0.01 mm.