Latopilumnus conicus, Ng & Clark, 2008

Ng, Peter K. L. & Clark, Paul F., 2008, A revision of Latopilumnus Türkay & Schuhmacher, 1985, and Aniptumnus Ng, 2002 (Crustacea: Decapoda: Brachyura: Pilumnidae) with larval comparisons, Journal of Natural History 42 (9 - 12), pp. 885-912 : 893-899

publication ID	https://doi.org/ 10.1080/00222930701869422
persistent identifier	https://treatment.plazi.org/id/7B088796-FFDC-FFF7-FE52-D806FEAEA4B1
treatment provided by	Felipe
scientific name	Latopilumnus conicus
status	sp. nov.

Treatment

Latopilumnus conicus View in CoL new species

( Figures 6–12 View Figure 6 View Figure 7 View Figure 8 View Figure 9 View Figure 10 View Figure 11 View Figure 12 )

Material examined

Conic Island Cave , 22 ° 219540 N 114 ° 239220E, Hong Kong. Holotype, „ (4.9× 3.3 mm), NHM 2003.690, coll. 21 October 2002 . Paratypes: 1 ovig. ♀ (3.6× 2.7 mm), NHM 2003.691, coll. 21 October 2002; 2 „„ (3.9× 2.8 mm, 3.3× 2.3 mm), 2 ♀♀ (4.8× 3.3 mm, 5.0× 3.4 mm), ZRC 2003.0343 View Materials , coll. 25 October 2002 ; 1 ovig. ♀ (3.2× 2.2 mm), NHM 2003.689, coll. 21 October 2002; 1 „ (3.8× 2.8 mm), 2 ♀♀ (4.0× 2.8 mm, 3.3× 2.3 mm), NHM 692-694, coll. 21 October 2002; 1 „ (3.6× 2.6 mm), NHM 2003.695, coll. 22 October 2002 .

Description of male holotype

Carapace transversely hexagonal, broader than long, regions not distinct, defined by shallow grooves, surface with patches of small rounded granules on frontal, gastric and branchial regions, most of surface visible, not covered by setae; anterior half of carapace, especially along margins, covered with scattered plumose setae of varying lengths, never completely obscuring surface, mostly aggregated around granules. Frontal margin distinctly bilobed, separated by shallow U-shaped notch medially, margin straight to gently convex, lined with numerous small granules; lateral frontal lobe very low, barely discernible, separated from median frontal lobe only by very shallow concavity or notch, separated from supraorbital margin by very shallow notch. Supraorbital margin granulated, entire. Anterolateral margin granulated, external orbital angle very low, hardly separated from very low first anterolateral tooth; second anterolateral tooth distinct, anterior margin shorter than posterior margin; third anterolateral tooth smaller than second tooth, acutely triangular. Posterolateral margin almost straight to slightly convex, converging towards gently convex posterior carapace margin. Basal antennal segment subrectangular, filling orbital hiatus. Orbits transverse; eyes filling orbital space; distal part of ocular peduncle covered with small granules. Infraorbital margin distinctly granulated, submedian part projecting anteriorly as low triangular tooth, visible from dorsal view. Suborbital, sub-branchial and pterygostomial regions granular. Merus of third maxilliped squarish, anterolateral angle not prominently produced, surface granular, especially marginally, inner margin granular; ischium subrectangular, with shallow submedian sulcus; exopod stout, distal edge almost reaching anterior edge of merus, inner subdistal tooth low, with long flagellum.

Chelipeds subequal, right larger. Inner margin of fused basis-ichium granular. Inner margin of merus with numerous small granules. Outer surface of carpus with numerous rounded granules, with scattered setae, inner distal angle produced as low tooth, lined with small granules. Outer surface of larger palm evenly covered with small rounded granules as well as scattered long setae and numerous short setae which obscures most of surface; fingers distinctly shorter than palm; outer surface of pollex with distinct longitudinal groove on subventral surface, lined with distinct longitudinal row of granules; cutting edges with basal teeth proportionately larger but not molariform. Outer surface of smaller chela covered with small rounded granules and numerous short setae which obscure most of surface; fingers shorter than palm; outer surface of pollex with deep submedian longitudinal groove lined with distinct longitudinal row of granules; cutting edges with several distinct teeth.

Ambulatory legs covered with scattered setae, especially on carpus and propodus, never obscuring surface or margin; second leg longest. Distal margin of basis-ischium of all legs almost smooth or with scattered small rounded granules, not comb-like. Dorsal margin of first to fourth meri serrated; proximal part of ventral margins smooth or with scattered small granules. Carpus with low submarginal ridge, outer margin with scattered small granules, otherwise unarmed. Dactylus gently curved with tapering tip.

Surfaces of anterior thoracic sternites relatively smooth, covered with short pubescence. Sternites 2 and 3 separated by almost straight groove; sternites 3 and 4 fused, demarcated only by lateral grooves, medially completely fused. Male abdomen with all segments freely articulating, surfaces almost smooth. Telson semicircular. G1 distinctly sinuous, distal part straight from ventral view, tapering to sharp tip. G2 very short, sigmoid.

Etymology

The species name is derived from its type locality, Conic Island in Hong Kong. Remarks

Latopilumnus conicus is similar to L. malardi and can only be reliably separated by its different G1 structure. In L. conicus , new species, the G1 is relatively shorter, with the entire structure gently sinuous and the distal part straight ( Figure 8D, E View Figure 8 ). In L. malardi , new combination, the G1 is proportionately longer, with the median part almost straight and the distal part is recurved and appears hooked ( Figure 4E–H View Figure 4 ). These differences are consistent for all the specimens examined.

The only other obvious morphological difference seems to be in size. Latopilumnus conicus is a much smaller species with the females already fully mature at carapace widths of about 3.0 mm. Latopilumnus malardi , new combination, is distinctly larger, but in view of the small number of specimens available, nothing more can be said. The form of the anterolateral teeth also seems to differ. Those of L. conicus , new species, are relatively lower and less granular ( Figure 8A View Figure 8 versus Figures 4A View Figure 4 , 5A View Figure 5 ). The outer lobe of the frontal margin of L. conicus is also prominently lower (appearing almost confluent with the rest of the margin, Figure 8A View Figure 8 ) than that of L. malardi , new combination, which is distinct ( Figures 4A View Figure 4 , 5A View Figure 5 ). In addition, the male telson of L. conicus , new species, is more semicircular in shape ( Figure 8C View Figure 8 ) whereas in L. malardi , new combination, it is more triangular ( Figure 4D View Figure 4 ).

Within the species, the form of the anterolateral teeth varies somewhat, with the second anterolateral tooth usually low but occasionally more dentiform. The fourth anterolateral tooth is usually the smallest but is sometimes subequal to the third tooth.