Eurhinocricus sp.

Golovatch, S. I., Mauriès, J. P. & Akkari, N., 2021, On the collections of Indo-Australian Spirobolida (Diplopoda) kept in the Zoological Museum of the Moscow State University, Russia. 3. Some Rhinocricidae, Arthropoda Selecta 30 (1), pp. 3-27 : 17-25

Eurhinocricus sp.

Figs 75–85 .

MATERIAL. 3 ♂♂, 1 ♀, 1 juv. ( ZMUM), Fiji, Viti Levu Island , Suva Botanical Garden, 16.III.1977, G.F. Kurcheva leg.

DESCRIPTION. Length 18–23 (♂) or 25 mm (♀), width 1.8–2.1 (♂) or 2.4 mm (♀). Adults with 36–38p+1–2ap+T segments. Colouration rather uniformly grey- to red-brown ( Figs 75–80 ), only antennae and legs light red-yellow, and eye patches blackish; a faint dorsal pattern of lighter, vague, paramedian, rather wide stripes consisting of comma-shaped spots on each ring ( Fig. 79 ).

Body cylindrical, postcollum constriction very faint ( Fig. 77 ). Head as usual, three small central teeth at fore margin of and a superficial, fine, axial suture on labrum, with ca. 10+10 labral and 2+2 supralabral setae. Eye fields subcircular, large, ommatidia flat, ca. 32–34 per patch, arranged in 6–7 vertical rows ( Figs 75, 76 ), isthmus ca. 2x diameter of eye patch ( Fig. 77 ). Antennae short and clavate, curved anteroventrad, in situ stretchable laterally behind caudal margin of collum; antennomeres 1–6 subequal in length, antennomeres 5–7 considerably more strongly setose than others, 7 th shortest, 8 th with four small apical cones ( Figs 75– 77 ). Tegument bare, smooth and mostly shining ( Figs 75– 80 ). Collum very broadly rounded and clearly, but rather narrowly bordered laterally ( Figs 75, 76 ). Midbody segments/rings devoid of evident sutures between zonae; meso- and metazonae unusually distinctly and densely striate across entire circumference, slightly more densely so ventrad, ca. 6–8 striae per square equal to their length just below ozopore level, longitudinal on metazonae, slightly oblique and directed dorsad on mesozonae, very delicate, dense, vertical and often confused on prozonae; striations on meso- and metazonae mostly regular, only in places abbreviated, confused only mid-dorsally and near ozopore ( Figs 75–80 ). Scobinae absent. Ozopores small, inconspicuous, starting with segment/ring 6, each pore lying upon line/suture just before metazona on a vague and minute boss. Telson ( Figs 75, 80 ) as usual, epiproct flat, caudally rounded and very small; paraprocts strongly and regularly convex, smooth, not bordered along caudal margin, with only a small and inconspicuous gutter between both valves; hypoproct strongly transverse and caudally rounded. Only ♂ segment 7 clearly swollen ventrally ( Fig. 75 ), a complete ring due to a strong ventral bridge in caudal half. Very small and numerous, light and irregular spots/sigilla on internal surface of meso- and metazonae ( Fig. 77 ).

Legs relatively long and slender (♂, ♀), ca. 2/3–3/4 as long as midbody height, each usually with a spine below and above claw; only ♂ legs 1 and 2 somewhat shorter; ventral sole pads wanting ( Fig. 75–78, 80 ).

Gonopods ( Figs 81–85 ). Anterior gonopods with a strong, median, slender, finger-shaped, apically rounded, sternal process (s), the latter only slightly longer than both coxa (cx) and telopodite (t) with its small, apical, rounded, laterally directed process (tp); cx the largest, with a strong, mesal, subtriangular, ventrally indistinctly tuberculate projection (mp) and a moderate apicolateral swelling (sw), both subtending a relatively slender t. Posterior gonopods connected with a small, membranous, ribbon-shaped sternum, each gonopod consisting of a short, stout, subcylindrical coxa (cx2) and a slender, much longer, bipartite telopodite (t2); apicolateral branch (lb) the largest, slender throughout, ribbon-shaped, slightly curved in subapical part, subtruncate apically; mesal branch (= solenomere, sl) much shorter, bacilliform, originating at about basal 1/3 and extending until about 1/5 of t2.

REMARKS. Superficially, had it not been for Fiji as the place of provenance, this species could have easily been described as new, because no Eurhinocricus sp. has ever been recorded south of the Mariana Islands in the southern Pacific. The species from Fiji is highly peculiar and easy to distinguish primarily in showing the metazonae clearly striated across the circumference ( Figs 75, 76, 78–80 ), while the gonopods, both anterior and posterior, are with several characteristically shaped outgrowths ( Figs 81–85 ). Moreover, the above specimens differ well from a (morphologically similar) unidentified species and the two hitherto described congeners from Micronesia at least in gonopodal structure. Thus, E. naufragus Carl, 1918 , from Atoll Uliti, Carolines, is a little larger (28–33 mm long and 3.5 mm wide, vs. 18–25 mm and 1.9–2.4 mm wide), shows considerably finer striations on meso- and metazonae (vs. far more strongly developed ones, Figs 75–80 ), the central sternal process of its anterior gonopods is parallel-sided (vs. broader at base, Figs 81–84 ), the telopodites are smaller (vs. larger), while the solenomere of the posterior gonopod is distinctly longer, nearly reaching the tip of the main branch (vs. considerably shorter, Figs 81, 82, 85 ) [ Carl, 1918]; E. saipanus Verhoeff, 1937 , from Saipan (= Guam), Marianas, so far as it can be derived from a very brief (and only verbal) original description [ Verhoeff, 1937], as well as based on type microscopic slides, shows a stronger, central, sternal process and unusually short telopodites of the anterior gonopods (vs. weaker and longer, respectively, Figs 81–84 ), while the main branch of the posterior gonopod is much more slender, suberect and truncate apically (vs. broader, curved subapically and subtruncate, Figs 81, 82, 85 ). The type material of E. saipanus , in the Zoological Museum in Munich (= Bayerische Zoologische Staatssammlung in München), contains one ♂ and one ♀, both partly in alcohol (ZSMA20070540) and partly in microscopic slides A 20031550, A 20031551 and A 20031552 ( Figs 86–88 ), of which A 20031551 and A 20031552 are designated herewith as representing the lectotype to ensure that the species is based on ♂ material. The gonopods of the lectotype ( Figs 89, 90 ) agree not only with Verhoeff’s [1937] brief account, which is natural, but also considerably with what Takakuwa [1942], in his review of the myriapod fauna of Micronesia, referred to as Eurhinocricus sp. , from Yap Islands, Carolines. Takakuwa [1942] totally omitted E. saipanus , apparently being unaware of it, but he described and illustrated his closer unidentified Eurhinocricus sp. as being 35 mm long and 3.5 mm wide, and generally rather well agreeing in gonopodal characters to E. saipanus ( Figs 89, 90 ). Especially the anterior gonopods are similar, including the unusually short telopodites. Still the Yap ( Figs 91, 92 ) and Saipan ( Figs 89, 90 ) samples fail to look conspecific because the main branch of the posterior gonopod in the former species is much more strongly expanded and elaborate distally compared to the latter one. In any event, more comparative material is clearly necessary to assess the Eurhinocricus diversity in Micro- and Melanesia. At the moment, all we can state is that Micronesia supports 2–3 species of Eurhinocricus . Strangely enough, Marek et al. [2003], in their global catalogue of Rhinocricidae , also omitted E. saipanus , even though Jeekel’s [2001] regional catalogue had provided a full account of that species.

Because the Fiji Islands support a wealth of rhinocricid species, mostly quite enigmatic and some even based on ♀ material alone, whereas the ZMUM samples come from a botanical garden, hence perhaps introduced, falling in synonymy seems to us very likely. As a result, we properly document and illustrate the ZMUM material even as not fully identified, in the hope that someday the taxonomic mess concerning the fauna of Fiji steps back, and the species becomes properly determined. Our Fiji samples are easily distinguished primarily in the body striations being unusually distinct and dense, covering the entire circumference of the meso- and metazonae ( Figs 75, 76, 78–80 ), while the gonopods are also highly characteristic ( Figs 81–85 ).

Jeekel [2001] provided a catalogue that contained as many as 24 species of Rhinocricidae known to occur in Fiji alone, most of which he assigned to Dinematocricus . Such an allocation was specially emphasized, and it was based on Jeekel’s vast personal experience in the study of Fiji’s rhinocricids, who found them all being tetraconocerate. In contrast, Evenhuis [2008], (http://hbs.bishopmuseum.org/ Fiji / checklists/diplopoda.html), listed most in Salpidobolus , a polyconocerate genus. We prefer to follow Jeekel’s [2001] opinion as obviously more credible. Because at least five species described from Fiji are listed among Rhinocricidae , Spirobolida or even Juliformia of uncertain status [ Jeekel, 2001], the only thing we believe appropriate at this stage is just to publish the first formal record of the genus Eurhinocricus from Fiji.

Figures

Figs 75–80. Eurhinocricus sp., # from Suva. 75 — habitus, lateral view; 76, 77 — anterior part of body, lateral and ventral views, respectively; 78, 79 — midbody segments, lateral and dorsal views, respectively; 80 — posterior part of body, lateral view. Pictures by K.V. Makarov, taken not to scale. Рис. 75–80. Eurhinocricus sp., # иЗ города Cува. 75 — обЩий вид, сбоку; 76, 77 — переднЯЯ часть тела, соответственно сбоку и сниЗу; 78, 79 — cреднЯЯ часть тела, соответственно сбоку и сверху; 80 — ЗаднЯЯ часть тела, сбоку. Фотографии К.В. Макарова, снЯты беЗ масШтаба.

Figs 81–85. Eurhinocricus sp., # from Suva. 81, 82 — both anterior gonopods and left posterior gonopod in situ, anterior and posterior views, respectively; 83, 84 — anterior gonopods, anterior and posterior views, respectively; 85 — right posterior gonopod, posterior view. Designations explained in text. Pictures by K.V. Makarov, taken not to scale. Рис. 81–85. Eurhinocricus sp., # иЗ города Cува. 81, 82 — оба передних гонопода, соответственно спереди и сЗади; 83, 84 — передние гоноподы, соответственно спереди и сЗади; 85 — правый Задний гонопод, сЗади. ОбЪЯснениЯ обоЗначений в тексте. Фотографии К.В. Макарова, снЯты беЗ масШтаба.

Figs 86–92. Eurhinocricus saipanus Verhoeff, 1937, type microscopic slides, including the gonopods of the lectotype, from Saipan, (= Guam), Marianas, and Eurhinocricus sp., # from Yap Islands, Carolines, after Takakuwa [1942]. Рис. 86–92. Eurhinocricus saipanus Verhoeff, 1937, типовые микропрепараты, включаЯ гоноподы лектотипа, с острова Сайпан (= Гуам), Марианские острова, и Eurhinocricus sp., # с островов Яп, Каролинские острова, по: Takakuwa [1942].