Syrioiulus lohmanderi, Vagalinski, 2020

Vagalinski, Boyan, 2020, A new species of Syrioiulus Verhoeff, 1914 from Iran, with remarks on the taxonomy of the genus (Diplopoda: Julida: Julidae), Revue suisse de Zoologie 127 (1), pp. 83-94 : 84-88

Syrioiulus lohmanderi sp. nov.

Figs 1-16

Material: MNHG; male holotype (fragmented into head, rings 1-6, left part of ring 7 and rest of body; gonopods, left antenna, leg-pair 1, leg-pair 2, penis, right leg 3, right edge of ring 7, and left mid-body leg dissected; left opisthomere prepared for SEM), sample field number 7314; label “ Iran (Gilan), Siahkal, tamis., mousse, creux gros arbres” [Iran, Gilan Province, Siahkal, sifting, moss, old, hollow trees]; 06.JUL.1973; leg. A. Senglet. – MNHG; 1 adult female paratype (fragmented into head to ring 3 and rest of body; right vulva dissected); 1 juvenile female paratype (unbroken); same collecting data as holotype .

Type locality: Iran, Gilan Province, Siahkal.

Etymology: Named in memory of Hans Lohmander (1896-1961), a prominent millipede taxonomist who described six species currently assigned to Syrioiulus .

Diagnosis: A blind species of Syrioiulus , particularly similar to S. astrabadensis ( Lohmander, 1932a) and S. persicus ( Golovatch, 1983) in gonopod and vulva structure. Different from S. astrabadensis mostly by its larger size and darker colouration, and by mesomeral process being subequal to rather than significantly shorter than solenomere. Different from S. persicus by absence of metazonal setae, and by presence of typical, pointed mesal apical denticle of promere (the same being a rounded lobe in the latter species).

Description

Measurements: Holotype with 60+1+T body rings, length 29 mm, mid-body vertical diameter 1.65 mm. Adult female paratype with 59+1+T body rings, length 28 mm, mid-body vertical diameter 1.9 mm. Juvenile female paratype with 49+4+T body rings.

Colouration (after more than 40 years of ethanol preservation) ( Figs 1-4 ): Mostly ochre brown, prozonae greyish with purple tinges; head with a dark, blurred, oval spot mesally to each antenna, and with a dark, narrow, axial line on vertex; body without axial line; legs and antennae light yellow to completely pallid; pre-anal ring and paraprocts darker ventrally.

General morphology ( Figs 1-4 , 5 ): Ommatidia absent; vertigial setae absent; 5 supralabral setae in the adult specimens, and 4 in the juvenile; 20-26 labral setae. Antennae ( Fig. 5 ) about 1.2 times as long as head in both sexes; antennomeres 3, 4, and 5 subequal in length, about 0.8 times as long as 2, and 1.5 times as long as 6, 5 considerably thicker than 6; a whorl of sensilla basiconica at distal margins of antennomeres 5 and 6, those on 5 nearly as long as the four apical cones, somewhat longer than those on 6. Gnathochilarium of normal julid appearance; promentum relatively short: considerably less than half the length of lingual lamellae; each lingual lamella bearing 4-5 setae. Collum smooth, some specimens with one to several very shallow grooves near posterolateral corners.

Prozonae with very short and shallow, scattered, longitudinal striae. Metazonae rather shallowly and somewhat irregularly striated, with 5-8 striae in a square with sides equal to metazonal length just below ozopore level; hind margins slightly turned outwards, bearing no setae. Ozopores set in metazonae, at 1/4-1/3 of metazonal length behind pro-metazonal suture; the latter indistinct, especially on dorsal side, recognizable only as a barely visible concentric groove running through middle of ring. Mid-body legs 1.55 and 0.95 times as long as midbody diameter in the adult male and in the adult female, respectively. Tarsus of mid-body legs 1.2-1.3 times as long as tibia, and about 3 times as long as apical claw.

Telson ( Fig. 4 ): Pre-anal ring dorsally with a few short setae; epiproct absent; hypoproct short and broadly rounded, tightly fitting under paraprocts in both sexes, with a pair of disto-median setae and a transverse row of around 10 setae proximally to the former. Paraprocts densely covered with long setae, without rows of short and stiff setae along caudal margins.

Male sexual characters: Mandibular stipites (see Fig. 1 ) forming rather small, rounded, frontoventral lobes. Legpair 1 ( Fig. 6 ) developed as compact hooks pointing mostly mesad, with a tapering tibial outgrowth and a minute, knob-like, tarsal remnant. Leg-pair 2 ( Fig. 7 ) with two crested adhesive pads, one each on postfemur and tibia. Leg-pair 3 ( Fig. 8 ) and following pairs additionally with a vestigial pad on femur; all pads gradually diminishing in size towards telson, completely disappearing in posterior third of body. Pleurotergum 7 ( Fig. 9 ) ventrally forming large, rounded lobes originating from the border between pro- and metazona, protruding mostly ventrad. Penis soft, hyaline, with deeply divided, conoidal lobes ending up in fingertip-like terminal lamellae turned slightly caudad.

Gonopods ( Figs 11-16 ): Promere ( Fig. 11 , P in Fig. 12 ) relatively slender and spoon-like, tapering, as high as opisthomere; width of shaft about 0.7 times that of bowl; ridge (r) massive and rounded, without freely protruding apical part; apical denticles well developed, clearly separated, mesal one running vertical, lateral one somewhat oblique, both with blunt tips pointing caudobasad. Opisthomere ( Figs 12-16 ) approximately halfway divided into mesomeral process (m) and solenomere (s), these being subequal in height, forming a broad sinus between them; mesomeral process running mostly straight, at considerable distance from solenomere, apically broadened and spade-like, with a strongly elongated mesal corner turned caudad, partly concealing solenomere, and with a nearly right-angled lateral corner bearing several minute spines/denticles; caudomesal lamella (cl) well-developed, forming a narrow ridge protruding completely mesad, thus being clearly visible in frontal and caudal views; solenomere slender, gradually bent anteriad, ending in two small processes [an anterior, fan-like (fp) and a posterior, shield-like one (sp)] surrounding a deep central concavity; a minute central filiform process (ff) visible in certain aspects; anterior lamella vestigial, recognizable only by several apical fringes.

Female sexual characters: Leg-pair 1 considerably, legpair 2 slightly flattened antero-caudally. Vulva ( Fig. 10 ) strongly compressed in the sagittal plane; bursa mostly symmetric: lateral valve (lv) slightly higher and more narrow than mesal one (mv); median cleft relatively broad; operculum (op) by far exceeding bursa, apical margin with a distinct mid-lateral incision and with several bumps along mesal section; setation moderately dense, randomly spread across whole surface of vulva. Receptaculum seminis consisting of a narrow, nearly straight central tube (ct) supporting a very short mesal tube (mt) ending in a small, ovoid, mesal ampulla (ma).

Remarks: The type locality of the new species lies in the foothills of the Alborz Mountains, the mountain range where most Syrioiulus species from Iran were exclusively recorded ( Fig. 18 ). The only exception is S. zarudnyi ( Lohmander, 1932a) which is known also from two localities in the central part of the country.

Considering the absence of ommatidia and the method (sifting dead organic matter) by which the studied specimens were collected, S. lohmanderi sp. nov. is likely an euedaphic species.

Figures

Figs 1-4. Syrioiulus lohmanderi sp. nov., overall appearance of male holotype (1, 2, 4) and female paratype (3), in MHNG. (1) Head and body rings 1-5. (2) Mid-body rings. (3) Head and collum. (4) Telson. Photos not to scale.

Figs 5-10. Syrioiulus lohmanderi sp. nov., structures of male holotype (5-9) and female paratype (10), in MHNG. (5) Antenna. (6) Leg-pair 1, frontal view. (7) Leg 2. (8) Leg 3. (9) Right ventral edge of pleurotergum 7, ventro-lateral view. (10) Right vulva, caudal, slightly mesal view.Abbreviations: ct = central tube; lv = lateral valve; ma = mesal ampulla; mt = mesal tube; mv = mesal valve; op = operculum. Scale bar of Fig. 8: 0.2 mm; the rest: 0.1 mm.

Figs 11-14. Syrioiulus lohmanderi sp. nov., gonopods of male holotype, in MHNG. (11) Left promere, caudal view. (12) Right pair of gonopods, mesal view. (13) Left opisthomere, caudal, slightly lateral view. (14) Distal parts of left opisthomere, lateral view.Abbreviations: cl = caudomesal lamella, ff = central filiform process, fp = fan-like process; m = mesomeral process; P = promere; s = solenomere; sp = shield-like process. Scale bar of Figs 11-13: 0.1 mm; Figs 14-15: 0.05 mm; Fig. 16: 0.01 mm.

Figs 15-16. Syrioiulus lohmanderi sp. nov., gonopods of male holotype, in MHNG. (15) Distal parts of left opisthomere, caudo-lateral view. (16) Solenomere, same aspect.

Fig. 18. Localities of Syrioiulus spp. in Iran. Ring: S. astrabadensis; cross: S. continentalis; square: S. discolor; pentagon: S. incarnatus; star: S. lohmanderi sp. nov.; filled circle: S. persicus; triangle: S. zarudnyi.