Chondrodesmus riparius Carl, 1914

Chondrodesmus riparius Carl, 1914 View in CoL

Figs 2–8

Chondrodesmus riparius Carl, 1914: 888 View in CoL , fig. 117 (original description).

Chondrodesmus riparius View in CoL — Attems, 1938: 82 (redescription after Carl [1914]); Kime & Enghoff, 2011: 49 (listed as introduced to Europe); Korsós & Lazányi, 2020: 93, fig. 1 (a summary of the records from Europe, first records from Hungary and Slovakia); Hollier et al., 2020: 225 View Cited Treatment ( type series).

Chondrodesmus cf. riparius View in CoL — Andersson & Enghoff, 2007: 2, figs 1 & 2 (first records from Sweden and Denmark, brief descriptive notes); Andersson et al., 2008: 173 (stating the records from Europe’s Nordic countries as first being imported from the Netherlands); Enghoff, 2008: 38, fig. 1 (summarizing the records from Europe and adding Germany to the list); Stoev et al., 2010: 104, fig. 7.2.8 (summarizing the records from Europe, adding Norway and outlining possible pathways of the introduction to Europe); Decker & Hannig, 2011: 13, fig. 5 (records from Germany); Bienias et al., 2021: 997, figs 1–3 (first records from Poland and Great Britain, first illustrations of the gonopods, first COI barcoding data and a reconstruction of the dated pathways of introduction to Europe).

Chondrodesmus riparius View in CoL — Kime & Enghoff, 2011: 49 (listed as introduced to Europe); Korsós & Lazányi, 2020: 93, fig. 1 (a summary of the records from Europe, first records from Hungary and Slovakia).

Type material examined. Syntype male ( MNHG), Colombia, Bodega Central , at Magdalena, 50 m a.s.l. ( Carl 1914) .

Material from Costa Rica. 1 male, 1 female, 1 juvenile ( ZISP MYR-DIP-0000009 , several fragments for barcoding), Costa Rica, Heredia Prov., La Selva Biological Station , 10°25'19"N 84°00'54"W, 17–23. VI GoogleMaps .2019, D. V. Logunov leg.; 2 males, 3 females ( ZISP MYR-DIP-0000194 ), Costa Rica , Puntarenas Prov., Punta Leona, lowland jungle, 9º42'17.7"N 84º39'43.7"W, 17. VI GoogleMaps .2019, D. V. Logunov leg.

Material from Denmark. 3 males, 2 juveniles ( NHMD 1184588 ), Denmark, Copenhagen, Østerbro, indoor in potted palm ( Phoenix roebelini O’Brien ), Jan.–Mar. 2007, A. Thomsen & H. Enghoff leg.

Description of material from Costa Rica. Samples from La Selva: Length ca 60 mm (male) or ca 58 mm (female), width on midbody pro- and metazona 5.5 and 10.0 mm (male), or 8.0 and 10.5 mm (female), respectively.

Samples from Punta Leona: Length ca 53–55 mm (male) or ca 50–62 mm (female), width on midbody pro- and metazona 5.5–6.5 and 9.5–10.0 mm (male), or 5.8–7.0 and 8.8–10.2 mm (female), respectively.

General coloration of dorsum dark chocolate brown to brown with subtriangular spots in posterior 2/3 to 1/2 paraterga and entire epiproct being contrasting yellow ( Fig. 2A–C). Head, antennae, entire venter and legs rather light reddish brown to yellow-brown ( Fig. 2D–F). Antennae occasionally nearly pallid. Gonopods yellow ( Fig. 2D, G, I–K). Males typically a little darker and brighter than females.

Integument very shining (dorsum and sides) to shining (sterna), prozona very delicately shagreened. Metaterga leathery, finely and mostly distinctly vermiculate to striolate, a little more clearly striolate at bases of paraterga ( Fig. 2A–F). Head largely bare, only a distinct row each of very dense labral and supra-labral setae. Interantennal isthmus ca 1.2–1.3 times as broad as diameter of antennal socket ( Fig. 2D). Antennae medium-sized, very slightly clavate, in situ barely extending past ring 3 (male) or 2 (female) dorsally. In length, antennomeres 2–6> 1=7.

In width, head <collum <ring 2 <3 <4 <5–15, trunk gradually and increasingly attenuated caudad thereafter. Paraterga set at about 1/2 midbody height, very well (male) or well developed (female), strongly and regularly sloping from dorsum. Paratergal anterolateral corners broadly and regularly convex and, on postcollum rings, with rimmed small shoulders. Sides faintly convex, lateral margins always narrowly rimmed and smooth. Paratergal posterolateral corners always acute, sharpened on collum, but mostly nearly pointed and rimmed at caudal margins, only paratergum 19 clearly shortened and rounded caudally ( Fig. 2A–C). Paraterga 1–4 drawn forward and their rings slightly concave caudally, following rings with caudally straight to increasingly concave margins. Paraterga declined increasingly caudad, only starting with ring 15 increasingly well projecting past rear tergal margin ( Figs 1–3). Pore formula normal, ozopores small: first dorsolateral, then increasingly dorsal, all lying inside distinct, moderately broad, low and lentiform peritremata very gradually turning into a narrowly rimmed anterolateral margin of paraterga ( Fig. 2A–C). Tergal and sternal setae/hairs fully abraded, but their insertion points on metaterga sometimes barely visible, albeit forming no sculpture. Pleurosternal carinae small ridges or denticles increasingly well reduced, but still traceable at least as small knobs until ring 18 (male) ( Fig. 2D) or ring 16 (female). Neither an axial line nor transverse mid-dorsal sulci. Strictures between pro- and metazona thin, but rather deep, very slightly striolate. Epiproct prominent, long, finger-shaped, with barely visible lateral subapical papillae, subtruncate at tip ( Fig. 2C). Hypoproct roundly subtriangular, with 1+1 long setae not borne on papillae. Limbus entire, thin, without peculiarities.

Sternum between male legs 1 very narrow, coxae being very short and subcontiguous. Sternum between male legs 2 similarly very small, but coxae much larger, nearly normal, each with a small digitiform gonapophysis. Following sterna broader, nearly flat, with faint cross-impressions and a small papilla or cone near each anterior and each posterior coxa, respectively ( Fig. 2D–F, H). Legs largely long, slender and poorly setose. Only leg-pairs 1 and 2 shorter and more densely setose, mostly ca 1.6–1.7 (male) or ca 1.2–1.3 times (female) as long as midbody height. In length, femur> tarsus> tibia> prefemur = postfemur> coxa; claw short, simple, curved ventrad ( Fig. 2D–F). Each prefemur with a very small, but conspicuous apicoventral spinule (male, female) ( Fig. 2D–F). Ventral chelae/pads absent even from male tibiae.

Gonopodal aperture regularly ovoid, small and simple ( Fig. 2G, H), ca 1.5 times as broad as long, not shifted onto prozonum 7, only lateral margins clearly elevated.

Gonopods ( Fig. 2G, I–K) simple, small, typical of the genus. Sternum inconspicuous and fully membranous. Coxite subcylindrical, simple, stout, about as long as telopodite, densely setose, with a simple and unciform cannula distomesally. Telopodite clearly bipartite, divided into a (1) strong, twisted, basally swollen, apically curved and blade-shaped prefemoral process ( a) with a small, ventral, midway lobule and a (2) slender, somewhat shorter, slightly curved, simple and attenuated solenomere ( sl) lying ventral to a. A conspicuous sharpened “knee” ( k) present at base of sl. Seminal groove running entirely on mesal side of telopodite before moving onto sl.

Brief notes on Danish material. Variations as opposed to the above Costa Rican samples: Width on midbody pro- and metazona 5.8 and 8.7 mm, respectively (male). Interantennal isthmus ~1.4 × diameter of antennal socket. Generally, the body length of European C. riparius is usually ca 50 (male) to 60 mm (female), the width ca 8 (male) to 9–10 mm (female). Males are usually somewhat smaller than females. All other morphological variations ( Figs 2–8), both somatic and gonopodal, are so minor and insignificant that they can unequivocally be considered as only infraspecific: this holds true when comparing all material of C. riparius studied, be this the syntype from Colombia, the new samples from Costa Rica or the individuals from Europe. This conclusion is reinforced through molecular evidence as well.

In Europe, C. riparius has mainly been found to occur in consumer flower pots with palms ( Chrysalidocarpus lutescens H. Wendl , originating from Madagascar, and Phoenix roebelini O’Brien , originating from China) ( Fig. 4). They have largely been distributed and its tracked year-to-year range expansion, since its presumed first introduction via the Netherlands to Sweden and Denmark in the 2000’s, are presented in Fig. 6, after Bienias et al. (2021).